Citation
Executive function deficits in adolescents with autism spectrum diagnosis : an analysis with a Tower of London task

Material Information

Title:
Executive function deficits in adolescents with autism spectrum diagnosis : an analysis with a Tower of London task
Creator:
Ready, Dana
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
Publication Date:
Language:
English

Thesis/Dissertation Information

Degree:
Doctorate ( Doctor of psychology)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
School of Education and Human Development, CU Denver
Degree Disciplines:
School psychology
Committee Chair:
Crepeau-Hobson, M. Franci
Committee Members:
Harris, Bryn
Stein, Rachel

Notes

Abstract:
Early identification of children with Autism Spectrum Disorder (ASD) may lead to important early intervention services that could potentially increase the quality of life for a large number of children. The purpose of this study was to examine executive functioning and planning abilities associated with ASD severity, as well as compare executive functioning and planning abilities in those identified with ASD to a normative population sample. Factors of interest included scores on the Autism Diagnostic Observation Schedule - Second Edition (ADOS-2) and the Tower of London Drexel University: 2nd Edition (TOL DX). Participants were thirty children between the ages of 7 to 14 who were identified with ASD at a small private clinic in a large city in the western United States. Data were collected via a retrospective review of records. Results of a correlation analysis indicated that ASD severity as measured by the ADOS-2 was not significantly associated with executive functioning and planning abilities as measured on the TOL DX. Comparison of the sample with the general population revealed significant differences in executive functioning as indicated via scores on several TOL DX scales. Results indicate that the ASD sample had significant deficits in executive problem solving and planning when compared with typical peers. Implications for both assessment and intervention with children with ASD are discussed.

Record Information

Source Institution:
University of Colorado Denver
Holding Location:
Auraria Library
Rights Management:
Copyright Dana Ready. Permission granted to University of Colorado Denver to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

Downloads

This item has the following downloads:


Full Text
EXECUTIVE FUNCTION DEFICITS IN ADOLESCENTS WITH AUTISM SPECTRUM
DIAGNOSIS: AN ANALYSIS WITH A TOWER OF LONDON TASK
by
DANA READY
B.S., Colorado State University, 2013
A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Psychology School Psychology Program
2019


The thesis for the Doctor of Psychology degree by Dana Ready
has been approved for the School Psychology Program by
M. Franci Crepeau-Hobson, Chair Bryn Harris Rachel Stein
Date: May 18, 2019


Ready, Dana (PsyD, School Psychology Program)
Executive Function Deficits in Adolescents With Autism Spectrum Diagnosis: An Analysis With a Tower of London Task.
Thesis directed by Professor Franci Crepeau-Hobson
ABSTRACT
Early identification of children with Autism Spectrum Disorder (ASD) may lead to important early intervention services that could potentially increase the quality of life for a large number of children. The purpose of this study was to examine executive functioning and planning abilities associated with ASD severity, as well as compare executive functioning and planning abilities in those identified with ASD to a normative population sample. Factors of interest included scores on the Autism Diagnostic Observation Schedule -Second Edition (ADOS-2) and the Tower of London Drexel University: 2nd Edition (TOL DX). Participants were thirty children between the ages of 7 to 14 who were identified with ASD at a small private clinic in a large city in the western United States. Data were collected via a retrospective review of records. Results of a correlation analysis indicated that ASD severity as measured by the ADOS-2 was not significantly associated with executive functioning and planning abilities as measured on the TOL DX. Comparison of the sample with the general population revealed significant differences in executive functioning as indicated via scores on several TOL DX scales. Results indicate that the ASD sample had significant deficits in executive problem solving and planning when compared with typical peers. Implications for both assessment and intervention with children with ASD are discussed.
The form and content of this abstract are approved. I recommend its publication.


IV
Approved: M. Franci Crepeau-Hobson


V
TABLE OF CONTENTS
CHAPTER
I. INTRODUCTION 1
II. LITERATURE REVIEW 3
III. METHODS 21
IV. RESULTS 26
V. DISCUSSION 28
REFERENCES 34


1
CHAPTER I INTRODUCTION
One of the most frequently encountered and studied conditions in the mental health field today is Autism Spectrum Disorder (ASD). The number of cases has risen dramatically over the last decade, and many hypotheses have been offered to assist with explaining this phenomenon. Today, the Centers for Disease Control reports that 1 in 59 children is identified with ASD (Baio et al., 2018). According to Matson & Kozlowski (2011), the numbers of ASD diagnoses will continue to rise. Many authors attribute this growing prevalence to changes in diagnostic criteria, greater public awareness, and lower age at diagnosis (Matson & Kozlowski, 2011; Kim et al., 2011). With the increase of ASD identification comes concerns regarding both identifying and meeting the specific needs individuals affected by the disorder.
Common traits associated with ASD include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides (Durand, 2014). Individuals with ASD typically experience difficulty with social communication which limits their abilities to interpret facial expressions and can inhibit their capacities to integrate emotions with dialogue (Kronke, Willard, & Huckabee, 2016). In addition to these hallmark characteristics of ASD, research suggests that children with this disorder also have difficulties in a number of areas related to executive functioning including, working memory, planning, inhibition, and cognitive flexibility (Verte, Geurts, Roeyers, Oosterlaan, & Sergeant, 2006). However, research findings have been inconsistent in this area - perhaps due in part to the varying ways in which ASD was identified in the studies, as well as with the tools used to assess executive functioning.


2
Problem and Significance
There is evidence that early identification and intervention mitigates ASD risk (Kroncke et al., 2016). According to Dawson’s (2008) theoretical model, early intervention may prevent the manifestation of many traits associated with ASD because young children are still experiencing neuroplasticity. Although many doctors utilize the ‘watch and wait’ approach, there has recently been a shift in the field to encourage early intervention for children who present with early signs of the disorder (Eapen, 2016). Consequently, assessing for easily identifiable deficits, such as those in executive functioning and planning may foster earlier intervention. Further, as ASD identification incorporates additional identifying features, it is important to recognize those deficits associated with ASD that are related to quality of life. Fostering the development of skills to enhance executive functioning and planning abilities through early intervention may mitigate future problems for those identified with ASD.
This research paper is guided by the following questions:
1. Are deficits in executive functions associated with planning and problem solving abilities associated with autism severity?
2. Do individuals identified with ASD have executive functioning deficits measured by the TOL DX in comparison to the normative sample in the following areas: executive problem solving and planning, behavioral inhibition and impulse control, cognitive flexibility, abstract/conceptual reasoning, rule-governed behavior, and monitoring?


3
CHAPTER II LITERATURE REVIEW
Autism Spectrum Disorder
In 1943, Leo Kanner first described 11 children who displayed isolated and repetitive behaviors. The following year, Hans Asperger described a group of children who demonstrated impaired social interactions and perseveration on select interests. Kanner and Asperger were both Austrian-born physicians who used the term “autistic” to describe such children (Barahona-Correa & Filipe, 2016). This description was based on Eugen Bleuler’s work, Dementia Praecox or the Group of Schizophrenias (1911). Interestingly, the physicians were unaware of the other’s writings (Barahona-Correa & Filipe, 2016). Autism Spectrum Disorder (ASD) was originally thought to result from a lack of affection from parents or guardians and was formerly characterized as a form of childhood schizophrenia. Today, however, we know this not to be true (Barna, 2017). ASD is a neurodevelopmental disorder that affects how an individual perceives social situations and the world around them.
Common traits associated with ASD include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides (Durand, 2014). Individuals with ASD typically experience difficulty with social communication which limits their abilities to interpret facial expressions and can inhibit their abilities to integrate emotions with dialogue (Kronke, Willard, & Huckabee, 2016). Both male and female adolescents diagnosed with ASD have been found to have increased levels of behavioral and emotional problems in comparison to their same aged peers (Pisula et al., 2017.) In the late 1980’s, the term “high-functioning autism” became increasingly popular and was used to


4
describe individuals diagnosed with autism who had “average or above average intelligence or language abilities in order to compare them to individuals with Asperger syndrome” (Diehl,
Tang, & Thomas, 2013, p. 1504). Currently, those who meet the criteria for high-functioning ASD are overrepresented in research and are becoming increasingly common in clinical evaluations, even though high functioning ASD it is not recognized in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5; American Psychological Association [APA], 2013).
An ASD diagnosis does not depend on intellectual ability and the severity of the disorder can be equivalent across levels of IQ (Joseph, Tager-Flushberg, & Lord, 2002); however, 46% of individuals diagnosed with ASD have average or above IQs (Trammell et al., 2013). Higher intelligence in individuals with ASD is associated with a greater plasticity, meaning these individuals have a greater potential to mitigate common ASD presentations (Kronke et al., 2016). Not surprisingly, individuals with higher IQs are often diagnosed with ASD at a later age than those with lower IQs (Mayes, & Calhoun, 2003). Those individuals with higher IQs who are diagnosed with ASD are likely to show greater benefit from intervention due to a greater cognitive capacity and the ability to respond to different types of therapeutic interventions (Kronke et al., 2016).
Executive Functioning
The last part of the brain to mature is also the largest anatomical part of the brain, the frontal lobes. According to Hadjikhani and Volkmar (2013), typically, the frontal cortex does not mature until the age of 20 and “can roughly be divided into the following parts with corresponding functions: Frontal operculum, language, mirror mechanisms. Precentral. Motor. Dorsolateral prefrontal, executive functions. Orbitofrontal/ventromedial. emotion, decision


5
making, response inhibition. Anterior cingulate: choice selection, reward, social emotion, empathy, response monitoring.” (p. 1333).
In 2014, Yuan and Raz studied the relationship between prefrontal cortex size and executive functioning ability in adults. The researchers found significantly better performance on executive functioning tests in those with a larger prefrontal cortex. There have been no differences found in the orbitofrontal cortex of individuals diagnosed with autism, but recent studies have found enlarged cerebral white and gray matter in toddlers diagnosed with autism, especially in the frontal, temporal, and cingulate cortices (Hadjikhani & Volkmar, 2013). Additionally, some research indicates that children diagnosed with autism have more neurons in the prefrontal cortex, a larger prefrontal cortex, and abnormalities in the inferior frontal gyrus, as well as differences in the cortical thickness of the inferior frontal cortex (Hadjikhani & Volkmar, 2013; Courchesne et.al., 2010). Courchesne, Redcay, and Kennedy’s findings (2004) determined that children diagnosed with ASD undergo abnormal brain development in their first four years of life. Specifically, study results indicated abnormally accelerated brain growth during the first two years of life, and then a decrease in the rate of development and even a complete lack of growth in some structures. This aligns with the theory of brain overgrowth in the first years of life for individuals identified with ASD, which is associated with deficits in executive functioning (Courchesne et.al., 2010).
Executive functioning refers to “the neuropsychological processes that enable physical, cognitive, and emotional self-control” (Corbett, Constantine, Hendren, Rocke, & Ozonoff, 2009, p. 1). The connection between a compromised frontal lobe and deficits in executive functioning was first made by Harlow in 1968. Bianchi’s work in the 1920’s revealed additional associations between frontal lobe lesions and difficulty completing complicated activities (Bianchi &


6
Macdonald, 1922). Building on Bianchi’s ideas, Luria (1966) proposed that complex processes underlie certain types of disorders, particularly those associated with damage to the frontal lobes. Similarly, Shallice (1988) described the frontal cortex as being essential for the planning of actions to take in the future. Interconnected with other cortical and sub-cortical structures, the prefrontal cortex has been credited with highly complex and multifaceted functions. Some would argue that the frontal lobe is what separates us from other mammals and provides us with our individuality and the ability to partake in higher order thinking and processes that help us attain goals (Unterrainer & Owen, 2006).
The relationship between cognition and emotion, as well as the awareness of executive functioning and its location in the brain was brought to light in the mid nineteenth century with the case of Phineas Gage. According to the Encyclopedia Britannica, due to a construction accident, Gage had a railroad tamping rod shot into his head, going through his brain and causing significant frontal lobe damage. Gage survived this accident and was even conscious and able to speak, but was found to be more impulsive, unkempt, crude, and irresponsible (Gearhart, 2018; Goldstein & Naglieri, 2013). Although an unexplainable anomaly at the time, we now understand that Gage’s frontal lobe damage impacted the affective components of cognitive processing and executive functioning abilities. More specifically, Gauge was prone to making poor decisions and exhibiting maladaptive behaviors when compared to his previous behavior, even though his cognitive ability seemed relatively intact (Goldstein & Naglieri, 2013).
The idea and conceptualization of executive functioning developed out of the observation of individuals who have changed due to frontal lobe damage. Groups of these individuals were observed by Luria and labeled as having dysexecutive syndrome. These individuals were able to perform within average ranges when undergoing cognitive assessments but were disorganized in


7
their everyday tasks and strategies (Goldstein & Naglieri, 2013). Today, we know that executive functioning is necessary to engage in healthy adaptive behavioral choices, and includes the processes of working memory, problem solving, planning, self-monitoring, self-motivation, and interference control (Goldstein & Naglieri, 2013).
Executive Functioning and ASD
In order to engage in healthy adaptive behavior in the real world, one must be capable of a constant exchange between both emotional and cognitive processes. An individual with inhibited cognitive flexibility has trouble with making adjustments based on feedback (Bacso & Nilsen, 2017). Hughes, Russell, and Robbins, consider executive functioning to be an umbrella term that encompasses “mental operations which enable an individual to disengage from the immediate context in order to guide behavior by reference to mental models or future goals” (1994, p. 477). These skills are typically associated with the frontal lobes, which are often implicated in individuals with ASD. Freeman, Locke, Rotheram-Fuller, and Mandell (2017) found that children with poorer executive functioning demonstrated increased playground isolation and less engagement with peers.
Damasio and Maurer (1978) suspect that the core of ASD symptoms might be executive functioning deficits. This may be associated with the unique structure of the frontostriatal neural network, which may lead to a lack of control when dealing with situations that are uncertain, difficult, or even situations that occur daily. (Goldstein & Naglieri, 2013). Individuals identified with ASD have impacted synchronization “between the frontal and posterior regions of the cortex” which is observable on a broad range of executive functioning measures (Goldstein & Naglieri, 2013, p. 123). Research suggests that children with ASD have difficulties in a number


8
of areas related to executive functioning including working memory, planning, inhibition, and cognitive flexibility (Verte, Geurts, Roeyers, Oosterlaan, & Sergeant, 2006).
Working memory is an extremely influential executive function as it can impact all other executive functions. In order to access working memory, an individual must be paying attention; and more specifically, one must attend to the correct information while simultaneously ignoring other unimportant stimuli (or practicing inhibition). In addition, the individual must be flexible and have the ability to shift between visual and verbal stimuli to process information. Finally, when using working memory, one must be able to track and choose to what information to react (Goldstein & Naglieri, 2013). Typically, individuals with ASD experience deficits in working memory due to associated executive functioning deficits, such as cognitive flexibility or planning. (Goldstein & Naglieri, 2013).
The ability to problem solve was first proposed by Alexander Luria (1973) as a cognitive ability formatted from "intention formation, planning, and programming" (Goldstein & Naglieri, 2013, p. 294). Kotovsky et al. (1985) found that when administered a measure of executive functioning called the Tower of Hanoi, participants used two different problem solving techniques that relate to two different cognitive processes. The first, referred to as 'exploratory behavior', refers to those who make random moves that could being the subject closer or further away from the intended goal. The second phase is called 'final path behavior' and refers to the recognition from the participant that there is a final sequence of moves that can be done to achieve a goal (Kotovsky et al., 1985). In alignment with Kotovsky et al. (1985), Zhang (1997) argues that the two phases represent different cognitive processes; therefore, clinical and developmental abilities may contribute to differences in problem-solving abilities. Consistent with this theory, Berg and Byrd (2002) studied the lengths of the separate phases with a similar


9
test, the Tower of London (TOL), and found that scores are sensitive to age and testing manipulations in younger populations.
Although for most people there is a clear relationship between adaptive functioning, conceptual reasoning, and problem solving, Williams et al. (2014) believe that this relationship is different for individuals identified with ASD. Research suggests that while those identified with ASD have the ability to implicitly learn, utilizing a flexible response to novel problems may be a contributing factor to problem solving difficulties for those identified with ASD (Williams et al., 2014).
Monsell (2003) described cognitive flexibility as the ability to rapidly “switch between tasks” (p. 134). Included in the DSM-5 diagnostic criteria for ASD are stereotypic and repetitive behaviors, as well as inflexibility in social and communication domains. Although there have been inconsistent findings in the relationship of cognitive flexibility and an ASD diagnosis, it is believed that a number of variables contribute to limited flexibility in those identified with ASD (Goldstein & Naglieri, 2013). These include a limited capacity to process new information, a lack of explicit instructions and/or predictability, and high working memory load.
Planning is the most consistent executive functioning domain found to be impaired in those identified with ASD. Planning involves several steps, and each step not only has to be stored, but possibly adjusted (Goldstein & Naglieri, 2013). Planning abilities change and become more complex with a child’s age, with children between the ages of 5 and 8 showing the greatest development and improvement in planning abilities (Romine & Reynolds, 2005). Hudson et al. (1995) discovered that young children around the age of three were able to use verbal abilities to plan for familiar tasks. This simple planning is more common in extremely young children. According to Levin et al. (1991), children between the ages of 7 and 11 are able to utilize


10
reasoning abilities and implement strategic behaviors that lead to competent and organized planning. Planning skills become more adult-like as children approach adolescence. Anderson et al. (2001) found that between the ages of 9-13, planning skills were similar to adults’ abilities on the TOL test.
Bennetto, Pennington, and Rogers (1996) used the Tower of Hanoi to assess the planning and problem-solving abilities in 11-24 year-olds identified with ASD via the Childhood Autism Rating Scale (CARS; Schopler, Reichler, & Renner, 1986). In comparison to the control group, those identified with ASD performed more poorly in terms of efficiency and they made more perseverative responses. In their study utilizing the Tower of Hanoi, Ozonoff and Jensen (1999) recruited forty 6-18 year-olds identified with ASD through the ADI-R (Lord et al., 1994) and Autism Diagnostic Observation Schedule (ADOS; Lord et al., 1989). They found those identified with ASD to have deficits in executive functioning associated with flexibility and planning.
Elizabeth Hill (2004a) critically reviewed the various foundational studies discussed above to find trends in executive functioning abilities in those identified with ASD. Hill found “that children, adolescents, and adults with autism experience an autism-specific deficit in planning in relation to normally developing individuals and those with other disorders not associated with generalized learning disability” (p. 195). These findings occurred with standard executive functioning assessments (e.g., Tower of Hanoi and Stockings of Cambridge), as well as alternative assessment like Luria’s Bar Task and the Milner mazes (Milner, 1965). Also in 2004, Hill published an article that expanded on her initial review of executive functioning abilities in those identified with ASD (Hill, 2004b). In this article, Hill specified that those identified with ASD were impaired in planning compared to the control groups, but this was only evident on puzzles that require a longer sequence of moves. Additionally, those with ASD had


11
greater success with the executive function of planning when they had a higher non-verbal mental age. This indicates that ASD might lead to an executive functioning deficit in planning but having a learning disability may also be a contributing factor (Hill, 2004b).
According to Robinson et al (2009), children identified with ASD and those with IQ scores in the lower limits of the average range have impaired planning abilities. Happe et al. (2006) found that those identified with ASD did not encounter the same difficulties on executive functioning measures as their normative comparison group. In this study, the researchers used a customized computerized executive functioning assessment that told participants what number of moves would allow them the total correct score for the prompt. Additionally, it encouraged participants to not make any moves until they had planned and could solve the solution in the correct number of moves. These adaptations and others made by Happe et al. (2006) may account for the difference in findings.
Inhibition is another area implicated in executive function deficits in individuals with ASD as they have been found to have trouble ignoring or suppressing irrelevant or interfering information. (Goldstein & Naglieri, 2013). According to Friedman & Miyake (2004), inhibition consists of prepotent response inhibition, resistance to distractor interference, and resistance to proactive interference. Prepotent response inhibitions usually present themselves as an urge or impulse to engage inappropriate behavior and having an appropriate inhibition control means that one is able to withhold “those urges in order to perform socially appropriate, and therefore acceptable behaviors” (Adams & Jarrold, 2012, p. 12). According to Friedmand and Miyake (2004), resistance to distractor interference relates to the capacity to ignore distractions in the external environment that are unrelated to task completion. This process relates to selective attention skills and is vital to completing any complex task. Resistance to proactive interference


12
relates to the ability to ignore or resist memories or information that is no longer relevant to the task (Friedmand & Miyake, 2004). This may seem similar to the resistance to distractor interference, but in resistance to proactive interference, the information that may cause interference was previously relevant to the task and is available before the target information is available (Friedmand & Miyake, 2004). Through meta-analysis, Pavina et al. (2018) found inconsistent findings in terms of ASD and inhibition, but concluded that those identified with ASD generally have some inhibitory deficit. Many of these inhibitory deficits were due to inattention rather than specified traits associated with ASD (Pavina et al., 2018).
Memari and colleagues (Memari et al., 2013) examined the relationship between the cognitive flexibility patterns and demographics of children aged 7-14 years old identified with ASD, Asperger’s Syndrome, and Pervasive Developmental Disorder not otherwise specified (PD NOS) through both the DSM-IV (American Psychiatric Association, 2000) and the Autism Diagnostic Interview - Revised (ADI-R; Lord, Rutter, & Le Couteur, 1994). The measure used to examine executive functioning abilities was the Wisconsin Card Sorting Test (WCST; Kongs, Thompson, Iverson, & Heaton, 2000. The parents of participants completed a background information form that gathered demographic information including parent education level, child age, gender, weight and height, education (grade level), medical history, and current medications Their results demonstrated that gender, not age, was best associated with cognitive flexibility ability in those identified with ASD (Memari et.al., 2013). Although gender was not always significantly related to performance when confounding factors are accounted for on the WCST, this finding aligns with Lemon et a.l (2001) who indicated there might be different behavior and cognitive profiles for girls and boys identified with ASD.


13
Van Eylen et.al. (2011) investigated the cognitive flexibility of children identified with ASD. The authors developed a task similar to the WCST, but with more task-switching variants. This variant needed additional disengagement to accomplish an appropriate switch and had a lower degree of instruction prior to task initiation. This resulted in all participants to have slower switching and to respond more slowly. On this WCST variation, those children identified with ASD had an increased switch cost when compared to their neurotypical peers. Additionally, those identified with ASD made more perseveration errors, though not to a significant degree. Similar to other research, findings from this study indicate that those identified with ASD have a difficult time with cognitive flexibility.
Merchan-Naranjo et.al. (2016) examined the executive functioning of patients identified with high-functioning ASD. Specifically, the researchers examined performance on a range of subtests from various neurological assessment. A comparison of the scores of the ASD group with those of healthy controls revealed significant differences demonstrating deficits in a number of executive functions, including attention, working memory, mental flexibility, problemsolving, and inhibitory control. These results indicate that despite having an IQ score within the Average range, participants in the ASD group still struggle with executive functioning impairments.
Chan et.al. (2009) looked at the executive dysfunction associations in children identified with ASD between the ages of 6-14 through the administration of the Test of Nonverbal Intelligence - 3rd edition (Toni-III; Brown et al., 1992), the Rey-Osterrieth Complex Figure Test (Rey-O; Bernstein and Waber, 1996), Hong Kong List Learning Test - 2nd edition (HKLLT; Chan, 2006), Object Recognition Test (OR; Snodgrass and Vanderwart, 1980), and Conners Continuous Performance Test II (CPT II; Conners, 2000). Results showed those identified with


14
ASD had higher levels of Intrusion, Delayed Intrusion, and False Alarms on the HKLLT, as well as higher levels of False Alarms on the OR, all of which are indicative of executive function deficits. On the CPT, the scores of students identified with ASD had such high levels of omission errors their data could not be included in the study. These numerous omission errors may have been due to participants not following the instructions. Similar to the Merchan-Naranjo et.al. (2016) study, analyses indicated that the significant differences were due to the ASD identification and were not related to IQ (Chan et al., 2009).
ASD Theories
Although deficits in executive functioning seemingly align with an ASD identification, ASD cannot be defined as something that arises due to executive functioning deficits (Geurts, Corbett, & Solomon, 2009) and the relationship is far from straight forward. Since ASD is a spectrum that represents a collection of heterogeneous disorders (Geurts et al., 2009), study findings can be inconsistent. In addition, measurement concerns and methodological differences have also contributed to inconsistencies in results (Geurts et al., 2009). Even within defined demographics, there are still considerable differences in executive functioning abilities for those identified with ASD (Goldstein & Naglieri, 2013). Due to these inconsistencies, no single theory of ASD has emerged; instead, there are several dominant ASD theories, including Central Coherence Theory and Theory of Mind (ToM).
Frith (1989) found that those identified with ASD experienced difficulty with context in spoken language and described this phenomena as “stemming from a failure of a central system whose job it is to integrate sources of information to establish meaning” (as cited in Jolliffe & Baron-Cohen, 1999, p. 149). In this theory, those identified with ASD have trouble attending to large patterns or global pieces of information and instead intensely focus on smaller pieces of


15
information with weak central coherence. (Jolliffe & Baron-Cohen, 1999). This theory emphasizes the cognitive processing or executive functioning aspects of ASD. Boyd et. al.
(2009) examined the relationship among the triad of clinical symptoms outlined in the DSM-IV for those identified with ASD, which includes restricted and repetitive behaviors, communication deficits, and social impairments. Using scores from the Behavioral Regulation Index of the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000) correlated with repetitive behaviors and the clinical expression of these behaviors, Boyd et.al. (2009) demonstrated that executive functioning deficits are not the underlying reason explanation for sensory features associated with ASD. These findings are contrary to Central Coherence Theory and suggest that something else underlies this aspect of ASD.
The ToM model examines the perspective of those identified with ASD and suggests that they have difficulty understanding the minds of those around them. More specifically, the ability to infer others’ emotions, feelings, thoughts, and beliefs. This approach provides an explanation for the social and communicative characteristics often associated with ASD (e.g., limited eye contact, echolalic language, etc; Fletcher, McConnell, Manola, & McConachie, 2014). Pellicano
(2010) conducted a longitudinal study assessing the relationship of the ToM, executive function, and central coherence in 37 children identified with ASD over the course of three years. She found that at the time of the intake, executive function and central coherence abilities were predictive longitudinally of changes in ToM performance, and these changes were independent of age, language, nonverbal intelligence, and early ToM skills (Pellicano, 2010). Consistent with Boyd et al (2009, Pellicano found no links between executive functioning and central coherence and their presenting co-occurring abnormalities in those identified with ASD were independent of each other. Although the relationship between executive functions and central coherence has


16
not been thoroughly examined, it is believed that the central coherence theory and executive functions relate to different aspects of the ASD spectrum (Goldstein & Naglieri, 2013).
Kouklari, Tsermentseli, and Auyeung (2018) used cross-sectional data obtained from children aged 8-12 identified with ASD to assess the association of executive functioning and ToM. Participants were administered subtests from the Delis-Kaplan Executive Function System (D-KEFS; Delis, Kaplan, & Kramer, 2001) including Sorting Test and Word/Color Interference. Additionally, participants were administered working memory digit recall and backwards digit recall (WMTB-C; Pickering & Gathercole, 2001), Reading the Mind in the Eyes (Children’s Version; Baron-Cohen et al., 2001), Children’s Communication Checklist (CCC; Bishop, 1998), and the Social Responsiveness Scale-second edition (SRS-2; Constantino & Gruber, 2012). Results demonstrated that executive functioning and ToM were selectively correlated to a significant degree when controlling for age and IQ. Additionally, working memory predicted ToM in both the control group and participants identified with ASD.
Ozonoff, Rogers, and Pennington (1991) compared the neuropsychological profiles of 23 individuals aged 8-20 years old with high functioning autism (HFA) and Asperger’s syndrome (AS). Through re-analysis of data from a former paper, the authors were able to separate the larger autistic sample into an HFA and an AS group based on scores on neuropsychological measures (Ozonoff et al., 1991). These neuropsychological profiles included the Tower of Hanoi as an executive functioning measure, as well as assessments that evaluated neuropsychological, intellectual, and social-cognitive domains. They found that compared to each other and the control group, the HFA group had the largest impairment in executive functioning, ToM composites, and emotional perception (1991). These results align with Ozonoff and McEvoy’s (1994) findings in a longitudinal study of 10-23 year-olds. This study examined the ToM ability


17
and executive functioning development over a 3-year time period and compared “nonretarded autistic adolescents with learning-disabled controls” (p. 415) matched on the demographics of age, IQ, gender, and socioeconomic status (SES). One assessment used to assess executive functioning was the Tower of Hanoi. Findings from this longitudinal study indicated that in those identified with ASD, both executive functioning and ToM abilities failed to improve with development (Ozonoff & McEvoy, 1994). These results suggest that those with impacted executive functioning abilities may never reach appropriate functional levels and these impairments are lifelong associations with ASD.
Although research has demonstrated that individuals with ASD do have impairments consistent with ToM, they also have impaired performance on tasks that do not require the understanding of another’s mental state. Research also suggests that the ToM and executive functioning closely align and participants are required to conceptualize (i.e., infer) what the experimenter wants them to do on most executive functioning tasks (Goldstein & Naglieri,
2013). Frye et al. (1996) argued that executive functioning abilities are necessary to perform many ToM tasks, while Perner and Lang (1999, 2000) believe that the skills necessary in the ToM model are required for the development of executive functioning. While the exact relationship between executive functioning and ToM in ASD is unclear, research has demonstrated that training executive functioning abilities in children with ASD seems to improve their performance on ToM tasks, whereas ToM training is not associated with improved executive functioning (Goldstein & Naglieri, 2013). It is speculated that this is because executive function may be a precursor to ToM or because the ToM is essential to executive control of action (Fisher & Happe, 2005). According to Goldstein and Naglieri (2013), the consensus is that


18
ToM and executive functioning abilities develop alongside each other and interact and both are impacted in those identified with ASD.
Although there is general consensus that individuals with ASD have various deficits in executive functioning (Hadjikhani, 2013), ASD is not described as an executive functioning disorder. This is because executive functioning deficits are not specific to those identified with ASD, as such deficits are associated with other disorders such as Attention Deficit Hyperactivity Disorder (ADHD; Goldstein & Naglieri, 2013) and not every person identified with ASD has executive functioning deficits. It is now hypothesized that ASD results from a complex interaction of cognitive deficits and/or styles such as ToM, with no single deficit sufficient or required for the diagnostic profile (Goldstein & Naglieri, 2013). According to Hadjikhani (2013), although there is no consensus in the field regarding the need to assess executive functioning abilities in ASD, additional research in this area is warranted to determine those processes that may contribute to ASD identification (Goldstein & Naglieri, 2013). Further, research examining performance on traditional tasks is warranted as individuals with autism have been found to perform better on computer administered neuropsychological assessments of executive functioning than those administered by humans (Goldstein & Naglieri, 2013).
The Tower of London task as an Assessment of Executive Functioning
Shallice developed the original Tower of London (TOL) task to assist with identifying frontal lobe and planning processes deficits. It was considered an adapted and simplified Tower of Hanoi test, but had problems that increased in difficulty (Krikorian, Bartok, & Gay, 1994).
The TOL task requires the individual to move three different colored beads around three prearranged pegs to match a pattern established by the examiner. Each peg holds one to three beads. After the examinee is shown their designated board and the administrator’s demonstration


19
board, they are then asked to make their board look like the demonstration board in as few moves as possible (Culbertson & Zillmer, 2005). After this, the two rules of the TOL task are introduced: participants may only place as many beads on a peg as a peg will allow (the first peg can hold up to three beads, the second peg up to two beads, and the third peg can hold only one bead); and only one bead may be moved at a time. The administrator copies the bead and peg patterns from the TOL task protocol and keeps track of the following scores: Total Moves, Rule Violations, Time Violations, Initiation Time, and Execution Time. Each pattern becomes progressively more difficult, in part due to having only the three available pegs to rearrange the beads.
The Tower of London Drexel University (TOL DX) was created by William C. Culbertson and Eric A. Zillmer in 1998. A revision and publication of a second edition was published in 2005. Although the TOL DX is similar to the original TOL, the TOL DX has differences in administration and scoring that “enhance the measure’s clinical utility, applicability, and standardization for children and adult populations” (Culbertson & Zillmer, 2005, p. 1). The authors of the TOL DX task created eight variables whose scores represent executive functions associated with an examinee’s planning and problem solving abilities (Culbertson & Zillmer, 2005). The specific abilities assessed by the TOL DX include impulse control and behavioral inhibition, cognitive flexibility, executive problem solving and planning, working memory, cognitive flexibility, abstract/conceptual reasoning, rule-governed behavior, and monitoring. The authors acknowledge that there is still much related to the precise cognitive processes underlying the TOL DX that is not understood; however, research suggests that the TOL DX assesses several of the above interrelated cognitive processes or “computations”


20
(Culbertson & Zillmer, 2005, p. 25). A number of these cognitive computations align with executive functions, which are thought to be processed in the frontal lobes of the human brain.
Individuals identified with ASD have reported to have impaired abilities across this task. Robinson, Goddard, Dritschel, Wisley, and Howlin (2009) conducted a study with 108 children aged 8-17 to compare TOL DX performance in children with and without ASD. ASD identification was made according to the Social Communication Questionnaire (SCQ), a 40-item parent checklist from the Autism Diagnostic Interview - Revised (ADI-R; Lord et al., 1994). The researchers found that participants with ASD performed worse on the TOL DX and there was an increase in the number of violations made, indicating impairment in planning difficulties. Their findings also demonstrated a significant positive correlation between rule violations and age.
Studies examining executive functioning in children with ASD have resulted in inconsistent findings, making it difficult to determine the neuropsychological profile of these individuals. The lack of consistent results may be due in part to methodological differences in studies, including when, where, and how ASD was diagnosed, as well as how executive functioning was assessed. The present study expands and improves upon research in this area by including participants who have been formally diagnosed with ASD by qualified professionals in a community-based clinic and by using a performance-based measure of executive functioning that requires the individual to utilize internal controls. This study aims to identify the relationship between an ASD identification and deficits in executive functioning as measured by the TOL
DX.


21
CHAPTER III METHODS
Participants
Participants were identified through a record review at a small private clinic in a large city in the western United States. Records for clients evaluated from January 1, 2016 to August 1, 2018 were reviewed. Inclusion criteria included meeting the diagnostic criteria for ASD as defined by DSM-V (APA, 2013) and completed intake information. Participants with neurological disorders that present at birth were not considered for this analysis due to the potential impact on executive functioning abilities. Study participants consisted of eight females (27%) and 22 (73%) males between the ages of 7 years, 8 months and 14 years, 3 months. Ten of the participants had a sole ASD identification. Eight of the participants had one additional diagnosis (generalized anxiety disorder, Attention-Deficit/Hyperactivity Disorder (ADHD)-predominantly inattentive presentation, ADHD -combined presentation, major depressive disorder, developmental coordination disorder, specific learning disorder with impairment in reading, or persistent depressive disorder with anxious distress) Eight participants were identified with ASD and two additional diagnoses, while two of the participants had a primary identification of ASD and three additional diagnoses. Ethnicity was not consistently documented at the private clinic and therefore was not considered in this study.
Measures
The Autism Diagnostic Observation Schedule, Second Edition (ADOS-2; Lord, Rutter, DiLavore, Risi, Gotham, & Bishop, 2012) is a “semi structured, standardized assessment of social interaction, communication, play, and imaginative use of materials for individuals suspected of having autism spectrum disorders” (Lord et al. 2000). The ADOS-2 is considered the ‘gold


22
standard’ of ASD assessments due to its strong predictive validity when tested against other best estimate diagnosis, internal consistency, and interrater reliability within domains (Gotham, Risi, Pickles, & Lord, 2007; Lord et al. 2000). There are four 30-minute modules. Module selection is based on a participant’s expressive language ability. ADOS-2 assessments include “a protocol of social presses” that consists of orchestrated social interactions to be scored (Gotham, Pickles, & Lord, 2009, p. 693). The examiner then introduces an assessment of behavioral items that assess social affect, restricted repetitive behaviors, and other common ASD traits through observation and interview. These are assessed using a 4-point scale, with 0 indicating ‘no abnormality of type specified’ and 3 indicating ‘moderate to severe abnormality.’ Specific items comprise an algorithm for each module; these items are summed and compared to thresholds, which results in a classification of‘autism,’ ‘autism spectrum disorder,’ or ‘nonspectrum’. Higher scores on the ADOS2I are an indication that an individual has a greater severity of impairment on items representing core indicators associated with ASD (Gotham et al., 2009). ADOS-2 Overall Total Scores have been used to measure ASD severity, but because the module selection and assessment is heavy on verbal language abilities, it is possible that an individual could have a score change with a targeted intervention (Gotham et al., 2009).
The Tower of London-Drexel (TOL DX; Culbertson & Zilmer, 1998) is a modified Tower of London (TOL; Shallice, 1982) used to assess childhood executive functioning. The original TOL was created to assess executive planning through the integration of cognitive and neuropsychological science. Shallice (1982) discovered scores on the TOL were independent of spatial problem-solving abilities and intelligence levels. Additionally, Shallice (1982) noted that patients with anterior and/or posterior cerebral lesions had difficulty with different facets of executive planning measured by the TOL, including taking a longer time to decide on an initial


23
move, as well as taking a longer time overall to solve the problem (Culbertson & Zilmer, 1998). The TOL DX was created by Culbertson and Zillmer (1998) and is considered a comprehensive measure of problem-solving and executive planning. It was found to have acceptable preliminary reliability and validity.
The TOL DX consists of ten prompts which increase in difficulty. The examinee is expected to match the presented formation by moving three colored beads on three pegs. The examinee is shown a prompt and timed while they attempt to recreate the visual prompt on their board. The examiner monitors the activity of the examinee and when the prompt is completed, records a number of scores that represent different aspects of an individual’s executive functioning abilities. TOL DX Scores include Total Moves Score, Total Correct Score, Total Rule Violation Score, Total Time Violation Score, Total Initiation Time Score, Total Execution Time Score, and Total Problem-Solving Time Score. Raw scores are converted into standard scores with a mean of 100 and a standard deviation of 15. The standard scores are computed such that a higher numerical value corresponds with better performance (fewer moves and rule violations, more correct items, and less time utilized), The one exception is on the Total Initiation Time Score. This standard score is computed so that a higher score reflects a longer initiation time or poorer performance. The neuropsychological factors associated with the TOL DX scores include executive problem solving and planning, behavioral inhibition and impulse control, attentional allocation, cognitive flexibility, abstract/conceptual reasoning, rule-governed behavior, and monitoring (Culbertson & Zilmer, 1998). The TOL DX 2nd edition was published in 2001 and featured an additional score for older adults, as well as expanded normative data to include children and adults in age from 7-80 years old (Culbertson & Zilmer, 2005).


24
Procedure
In order to identify participants who met inclusion criteria for the study, a review of evaluations was conducted at the private clinic. If the clinical evaluation battery included the TOL DX and an ASD identification, then the record was pulled and reviewed. Files were collected alphabetically and reviewed to see if a psychological report was present in the file. If a psychological evaluation was present, then the next step was to determine if the record aligned with inclusion criteria. If the record did meet the inclusionary requirements, then the record was reviewed and the de-identified data was recorded onto a password-protected server.
Predictor variables were coded using dummy variables. For example, those identified with ASD and generalized anxiety disorder were coded as 1 (ASD) and 2 (generalized anxiety disorder). Total age of participants was recorded and converted into months. For example, a participant whose age was 7 years and 8 months at the time of testing was coded as 92 months for analysis. All scores from the ADOS-2 and TOL DX were recorded for analysis.
Data Analyses
Correlational analyses were conducted to investigate the Research Question 1: Are deficits in executive functions associated with planning and problem solving abilities that are associated with autism severity? Specifically, correlations were run examining the relationship between ADOS-2 Overall Total Score and ADOS-2 Comparison Scores and TOL DX scores (Total Move Score (TMS; sum of all moves, above the minimum required, in all ten trials), Total Correct Score (TCS; trials out of 10 that are completed using fewest moves possible), Total Rule Violation Score (RVS; number of times test rules are violated), Total Time Violation Score (TTV; number of trials requiring > 60 seconds to complete), Total Initiation Time Score (IT; total time taken in each trial before making first move), Execution Score (ET; total time from the


25
first move to completion of each trial), and Total Problem Solving Score (PST; total time taken for each trial),). Pearson’s r was used to determine if there were significant correlations among the variables.
One Sample T-Tests were conducted to investigate Research Question 2: Do individuals identified with ASD have executive functioning deficits measured by the TOL DX in the following areas; executive problem solving and planning, behavioral inhibition and impulse control, cognitive flexibility, abstract conceptual reasoning, ride-governed behavior, and monitoring in comparison? The dependent variables were TOL DX scores (TMS, TCS, RVS, TTV, IT, ET, PST). These analyses compared the TOL DX scores of the study sample with those of the normative sample.


26
CHAPTER IV RESULTS
Thirty participants met the inclusion criteria for the study. Eight participants were female (27%) and 22 were male (73%). They ranged in age from 7 to 14 years (Mean=9 years, 9 months; 117.7 months). ADOS-2 and TOL DX Scores are presented in Table 1.
Table 1
Age, Gender, ADOS-2 scores, and TOL DX Scores
N Minimum Maximum Mean Standard Deviation
Age (months) 30 85 171 117.70 22.01
ADOS-II Overall Total Score 30 6 24 15.53 4.09
ADOS-II Comparison Score 30 3 10 8.47 1.66
TOL DX Total Move Score 30 60 114 87 14.59
TOL DX Total Correct Score 30 2 132 88.33 21.40
TOL DX Total Rule Violation Score 30 60 108 80.93 20.96
TOL DX Total Time Violation Score 30 60 118 94.93 18.66
TOL DX Total Initiation Time Score 30 84 150 99.47 12.84
TOL DX Total Execution Time Score 30 60 118 95.60 15.95
TOL DX Total Problem Solving Time Score 30 60 118 95.87 15.99
Autism Severity and Executive Functioning
Pearson correlations were run to examine the association between autism severity and executive functioning as measured by the TOL DX. None of the TOL DX scores were significantly correlated with ADOS2I Total Scores. These findings indicate that deficits in executive functioning are not related to autism severity.
Executive Functioning and ASD Diagnosis


27
A One Sample T-Test was conducted to determine if the samples’ TOL DX average scores differed significantly from that of the normative sample (M=100). Assumptions were checked and met. The study sample earned significantly lower Total Move Scores (TMS; M=87, SD=14.9) than the general population, t(29)=-4.88(), p< 05. Additionally, Total Correct Score (TCS) was significantly lower (M= 88.33, SD= 21.4), t(29)= -2.99, p<05. Finally, the study sample earned significantly lower Total Rule Violation Scores (TRV; M= 80.93, SD= 20.96) t(29)= -4.984, p<05. No other significant differences in TOL DX scores were observed. Table 2 displays descriptive statistics for the TOL DX scores.
Table 2
Descriptive statistics for TOL DX (n=30)
Outcome Mean SD
TOL DX Total Move Score* 87 14.59
TOL DX Total Correct Score* 88.33 21.40
TOL DX Total Rule Violation Score* 80.93 20.96
TOL DX Total Time Violation Score 94.93 18.66
TOL DX Total Initiation Time Score 99.47 12.84
TOL DX Total Execution Time Score 95.60 15.95
TOL DX Total Problem Solving Time Score 95.87 15.99
*P< 05


28
CHAPTER V DISCUSSION
Autism Spectrum Disorder (ASD) is a highly prevalent developmental disability with 1 in 59 children identified with the disorder in 2014 (Baio et al., 2018). Individuals with ASD present with deficits in social communication and social interaction and restricted, repetitive patterns of behavior, interests, or activities (APA, 2013). In addition to these hallmark characteristics of ASD, research suggests that children with this disorder also have difficulties in a number of areas related to executive functioning including, working memory, planning, inhibition, and cognitive flexibility (Verte et al., 2006). However, research findings have been inconsistent int his area -perhaps due in part to the varying ways in which ASD was identified in the studies, as well as with the tools used to assess executive functioning.
The purpose of this study was to examine the relationship between Autism Spectrum Disorder (ASD) identification and executive functioning abilities. Specifically, the study sought to investigate if ASD severity is associated with planning and problem solving abilities. Additionally, the study aimed to determine if individuals identified with ASD have deficits in executive functioning abilities as measured by an objective, performance-based measure: the Tower of London - Drexel University (TOL DX) when compared with the normative sample. Participants were 30 children ages 7-14 who were identified with ASD via a comprehensive evaluation conducted by a qualified professional. A correlation analysis found no significant relationships among the TOL DX scores and ADOS-2 Total scores, indicating that ASD severity was not related to deficits in executive functioning as measured by the TOL DX. This finding is


29
consistent with previous research that examined this relationship using executive functioning rating scales (van den Bergh, Scheeren, Begeer, Koot, & Geurts, 2014).
When comparing the average scores of the normative sample on the TOL DX to ASD sample, several significant relationships were found, including; Total Move Score (TMS), Total Correct Score (TCS), and Total Rule Violation Score (RVS), with the study sample earning significantly lower scores on each of these scales. The TOL DX scales are measures of executive problem solving, planning, and impulse control (Culbertson & Zillmer, 2005). These results indicate that individuals with ASD have deficits in each of these areas. Robinson, Goddard, Dritschel, Wisley, and Howlin (2009) found similar results when assessing children identified with ASD with the TOL DX. Their study found that children with ASD used significantly more moves to complete prompts and had significantly more time violations in comparison to their normative peers.
The significantly lower TMS and RVS found in the ASD sample also aligns with Robinson, Goddard, Dritschel, Wisley, and Howlin’s (2009) findings. However, results of the present study contradict those obtained by Happe et al. (2006), who found that those identified with ASD did not have planning deficits. This discrepancy may be due to the numerous adjustments made in the assessment administered by Happe et al. (2006), which included: using a computerized version, not being able to execute ‘illegal’ moves, a visual indication of the minimum number of moves required to complete a prompt, encouragement to not start the prompt until a plan had been formulated, six practice trials, and adjustments in assessments given to high-functioning participants. These adaptations and the resulting additional information provided to participants during administration may have altered the planning approaches used by those identified with ASD, resulting in better performance.


30
Results from this study indicate that individuals identified with ASD have significant deficits in executive problem solving, planning, and impulse control compared to the general population. The significantly lower TMS indicates that the ASD sample used more moves than the normative sample to solve the same prompts on the TOL DX. This significance may be due to the two phenomena. When presented with a TOL DX formation, the examinee engages in one of two problem solving techniques known as exploratory behavior and final path behavior. On the TOL DX, when an examinee makes random moves that may bring them closer or further away from their intended goal, they are engaging in exploratory behavior. When an examinee recognizes the final sequence of steps that must be taken to achieve their goal, they are engaging in final path behavior (Kotovsky et al., 1985). The lower TMS demonstrates that those with ASD used more moves to complete the prompts; therefore, they either spent more time in the exploratory behavior phase that resulted in additional random and ineffective moves, or they had ineffective final path behavior that required more moves than necessary to complete the prompt. Deficits in these phases and lower scores on the TMS are indicative of ineffective executive planning abilities, due to an examinee's limited capacity to utilize age appropriate reasoning abilities to implement strategic behavioral strategies to accomplish a goal (Levin et al 1991). Since planning has consistently be an executive functioning domain found to be most impacted in those identified with ASD (Goldstein & Naglieri, 2013), it came as no surprise that the ASD sample had significant more difficulty with this domain compared to the normative sample. The ability to plan is essential for decision making activities, as well as being able to anticipate what may occur. Planning is an adaptive skills that is necessary in daily activities, such as dressing appropriately according to the weather and packing a lunch for later in the day. The ability to use previously obtained knowledge to change our behavior is important for adequate self-sufficiency


31
and effective decision making skills. As we anticipate future actions, it is necessary to comprehend constraints that may limit our actions, understand the consequences our actions may pose, and adapt to changes in our day.
Impulse control and inhibition are also known to be associated with an ASD identification (Payina et al., 2018). The significant difference in the RVS observed in the present study indicates that those with ASD experienced more difficulty inhibiting behavior that was previously outlined as against the rules. Pavina and colleagues hypothesized that such inhibitory deficits are likely due to inattention rather than specified traits associated with ASD (Pavina et al., 2018). The findings of the present study provide support for this as lower scores on measures of executive functioning were not associated with autism severity.
Our executive functioning and planning abilities assist us in our daily lives through making appropriate adaptive behavioral choices through the use of working memory, problem solving, planning, self-monitoring, self-motivation, and interference control (Goldstein & Naglieri, 2013). Children with impacted executive functioning tend to be more isolated in unstructured play settings, and engage less with their peers (Freeman, Locke, Rotheram-Fuller,
& Mandell, 2017). In this study, those identified with ASD were found to have significant difficulty in the areas of executive problem solving, executive planning, and impulse control. These deficits may serve to exacerbate the social communication and social skills deficits inherent to ASD.
Limitations
While the results of this study serve to advance our knowledge of executive functioning in individuals with ASD, there are many limitations to this study that should be noted. First is the small sample size. This may have resulted in insufficient power to determine effects of autism


32
severity. In addition, due to a lack of documentation, racial, cultural, and socio-economic factors could not be considered in the analyses, which limits the generalizability of this study to other groups. This study only examines an ASD identification according to scores on two standardized assessments (the ADOS-2 and TOL DX). Additional assessments may have contributed to further analysis of executive functioning abilities and traits associated with ASD.
Future research should examine differences across gender, racial, cultural, and socioeconomic factors. Additionally, as executive functioning abilities progress throughout an individual’s life, assessing deficits in relation to developmental level and age would be extremely beneficial. Finally, the assessment of executive functioning was limited to functions measured by the TOL DX. More targeted assessments that focus on the time a participant spends in the exploratory behavior cognitive process vs. the final path behavior cognitive process would be beneficial for understanding where more specified deficits exist.
Conclusion
ASD is a neurodevelopmental disorder that affects how an individual perceives and interacts with the world around them. Common traits associated with ASD include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides. Early intervention is key to enhancing the quality of life with those identified with ASD; consequently, accurate and early identification is critical in mediating the negative effects of the disorder. This study aimed to examine the executive functioning in children identified with ASD. Previous research has indicated that executive function deficits are implicated in autism, though no clearly identifiable profile in this regard has emerged. This may be due in part to methodological differences in previous studies, including in how ASD was diagnosed and how executive functioning was assessed. The present study sought to overcome


33
some of the limitations of previous research by including participants who were diagnosed with ASD by a qualified professional and the use of a standardized, performance-based measure of executive functioning.
ASD severity as indicated on the ADOS-2 Overall Total Score was not found to be a contributing factor in executive functioning and planning deficits as measured on the TOL DX. However, those identified with ASD were found to have significant deficits in executive problem solving, planning, and impulse control. Collectively, these findings suggest that children with ASD have such deficits regardless of degree of severity of the disorder. When planning for assessment and intervention, it is important to account for both the executive functioning abilities of the individual, as well as the ASD symptom presentation. The highly restricted and disruptive behaviors, inhibited social communication, impacted facial expression interpretation, and restricted integration of emotions and dialogue are all presented at differing levels of severity according to the individual identified with ASD. Additionally, these associative traits co-exist with impacted executive functioning, and need individualized and targeted early intervention. Addressing individual symptoms, executive functioning, and planning deficits with assessment and intervention will result in a drastically improved quality of life for the individual.


34
REFERENCES
Adams, N. C., & Jarrold, C. (2012). Inhibition in autism: Children with autism have difficulty inhibiting irrelevant distractors but not prepotent responses. Journal of Autism and Developmental Disorders, 42(6), 1052-1063.
American Psychiatric Association (2013). Diagnostic and statistics manual of mental disorders (5th ed.) Arlington, VA: American Psychiatric Publishing.
Bacso, S. A., & Nilsen, E. S. (2017). What’s that you’re saying? Children with better executive functioning produce and repair communication more effectively. Journal of Cognition and Development, 75(4), 441-464 .
Baio, J., Wiggins, L., Christensen, D. L., Maenner, M. J., Daniels, J., Warren, A.,... Dowling,
N. F. (2018). Prevalence of autism spectrum disorder among children aged 8 years — Autism and developmental disabilities Monitoring network, 11 sites, United States,
2014. MMWR Surveillance Summary, 67(SS-6), 1-23.
DOI: http://dx.doi.org/10.15585/mmwr.ss6706al
Barahona-Correa, J. B., & Filipe, C. N. (2016). A concise history of Asperger syndrome: the short reign of a troublesome diagnosis. Frontiers in Psychology, 6, 2024.
Barna, M. (2017). Autism spectrum disorder. Discover, 38(6), 62.
Baron-Cohen, S., Wheelwright, S., Scahill, V., Lawson, J., & Spong, A. (2001). Are intuitive physics and intuitive psychology independent? A test with children with Asperger Syndrome. Journal of Developmental and Learning Disorders, 5, 47-78.
Bennetto, L., Pennington, B. F., & Rogers, S. J. (1996). Intact and impaired memory functions in autism. Child Development, 67(A), 1816-1835.
Berg, W. K., & Byrd, D. L. (2002). The Tower of London spatial problem-solving task:
Enhancing clinical and research implementation. Journal of Clinical and Experimental
Neuropsychology, 24(5), 586-604.
Bernstein, J. H., Waber, D. P., & Oedssa, F. L. (1996). Developmental scoring system for the Rey- Osterrieth Complex Figure. Lutz, FL.: Psychological Assessment Resources.
Bianchi, L., & Macdonald, J. H. (1922). The mechanism of the brain and the function of the frontal lobes. Berkeley, C A: University of California Libraries
Bishop, D. M. V. (1998). Development of the Children’s Communication Checklist (CCC): A method for assessing qualitative aspects of communicative impairment in children. Journal of Child Psychology and Psychiatry, 39(6), 879-891


35
Boyd, B. A., McBee, M., Holtzclaw, T., Baranek, G. T., & Bodfish, J. W. (2009). Relationships among repetitive behaviors, sensory features, and executive functions in high functioning autism. Research in Autism Spectrum Disorders, 5(4), 959-966.
Brown, L., Sherbenou, R. J., & Johnsen, S. K. (1992). Test of Nonverbal Intelligence: A language-free measure of cognitive ability. 3rd ed. Austin, TX: PRO-ED.
Chan, A. S., (2006). Hong Kong List Learning Test. 2nd ed. Hong Kong: Department of
Psychology and Clinical Psychology Centre, The Chinese University of Hong Kong.
Chan, A. S., Cheung, M. C., Han, Y. M., Sze, S. L., Leung, W. W., Man, H. S., & To, C. Y. (2009). Executive function deficits and neural discordance in children with autism spectrum disorders. Clinical Neurophysiology, 120(6), 1107-1115.
Conners, C.K. (2000). Conner’s Continuous Performance Test II. ON: Multi-Health System.
Constantino, J. N., & Gruber, C. P. (2012). Social Responsiveness Scale (2nd ed.). Los Angeles, CA: Western Psychological Services.
Corbett, B. A., Constantine, L. J., Hendren, R., Rocke, D., & Ozonoff, S. (2009). Examining executive functioning in children with autism spectrum disorder, attention deficit hyperactivity disorder and typical development. Psychiatry Research, 166(2), 210-222.
Courchesne, E., Mouton, P. R., Calhoun, M. E., Semendeferi, K., Ahrens-Barbeau, C., Hallet, M. J., ... & Pierce, K. (2010). Neuron number and size in prefrontal cortex of children with autism. JAMA, 506(18), 2001-2010
Courchesne, E., Redcay, E., & Kennedy, D. P. (2004). The autistic brain: birth through adulthood. Current opinion in neurology, 17(4), 489-496.
Culbertson, W. C., & Zillmer, E. A. (1998). The Tower of LondonDX: A standardized approach to assessing executive functioning in children. Archives of Clinical Neuropsychology, 75(3), 285-301.
Culbertson, W. & Zillmer, E., (2005). The Tower ofLondon-Drexel University: 2nd Edition. North Tonawanda, NY: Multi-Health Systems, Inc.
Damasio, A. R., & Maurer, R. G. (1978). A neurological model for childhood autism. Archives of neurology, 55(12), 777-786.
Dawson, G. (2008). Early behavioral intervention, brain plasticity, and the prevention of autism spectrum disorder. Development and psychopathology, 20(3), 775-803.
De Beni, R., Palladino, P. (2004). Decline in working memory updating through ageing: intrusion error analyses. Memory, 12, 75-89.
Delis, D. C., Kaplan, E., & Kramer, J. H. (2001). Delis Kaplan Executive Function System. San Antonio TX: Psychological Corporation)


36
Diehl, J., Tang, K., Thomas, B. (2013) High-functioning autism (HFA). In: Volkmar F.R. (eds) Encyclopedia of Autism Spectrum Disorders. Springer, New York, NY
Durand, V. M. (2014). Autism spectrum disorders: Background and cases. In V. M. Durand,
AutismSspectrum Disorder: A Clinical Guide for General Practitioners (pp. 9-15).
Eapen, V. (2016). Early identification of autism spectrum disorder: Do we need a paradigm shift? Australian and New Zealand Journal of Psychiatry, 50(8) 718-720.
Fisher, N., & Happe, F. (2005). A training study of theory of mind and executive function in children with autistic spectrum disorders. Journal of Autism and Developmental Disorders, 55(6), 757-771. doi:10.1007/sl0803-005-0022-9
Fletcher-Watson, S., McConnell, F., Manola, E., & McConachie, H. (2014). Interventions based on the theory of mind cognitive model for autism spectrum disorder (ASD). The Cochrane Database of Systematic Reviews, (3), CD008785. doi: 10.1002/14651858.CD008785.pub2
Freeman, L. M., Locke, J., Rotheram-Fuller, E., & Mandell, D. (2017). Brief Report: Examining Executive and Social Functioning in Elementary-Aged Children with Autism. Journal of Autism and Developmental Disorders, 47(6), 1890-1895.
Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: A latent-variable analysis. Journal of Experimental Psychology: General, 733(1), 101-135. doi: 10.1037/0096-3445.133.1.101
Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: a latent-variable analysis. Journal of Experimental Psychology: General, 733(1), 101.
Frith, U. (1989). Autism: Explaining the enigma. Blackwell Oxford Google Scholar.
Frye, D., Zelazo, P. D., Brooks, P. J., & Samuels, M. C. (1996). Inference and action in early causal reasoning. Developmental Psychology, 32(1), 120-131.
Gearhart, S. (2018). Phineas Gage. EncyclopaediaBritannica. Retrieved from https://academic-eb-com.aurarialibrary.idm.oclc.org/levels/collegiate/article/Phineas-Gage/604924
Geurts, H. M., Corbett, B., & Solomon, M. (2009). The paradox of cognitive flexibility in autism. Trends in Cognitive Sciences, 73(2), 74-82.
Gioia, G. A., Isquith, P. K., Guy, S. C., & Kenworthy, L. (2000). Test review behavior rating inventory of executive function. Child Neuropsychology, 6(3), 235-238.
Goldstein, S., & Naglieri, J. A. (Eds.). (2013). Handbook of EFunctioning. Springer Science & Business Media.


37
Gotham, K., Pickles, A., & Lord, C. (2009). Standardizing ADOS scores for a measure of
severity in autism spectrum disorders. Journal of Autism and Developmental Disorders, 39(5), 693-705.
Gotham, K., Risi, S., Pickles, A., & Lord, C. (2007). The autism diagnostic observation schedule (ADOS): Revised algorithms for improved diagnostic validity. Journal of Autism and Developmental Disorders, 37, 400-408. doi: 10.1007/sl0803-006-0280-l.
Hadjikhani, N. (2013). Frontal lobe findings in autism. In Encyclopedia of Autism Spectrum Disorders (pp. 1333-1339). Springer, New York, NY.
Happe, F., Booth, R., Charlton, R., & Hughes, C. (2006). Executive function deficits in autism
spectrum disorders and attention-deficit/hyperactivity disorder: examining profiles across domains and ages. Brain and Cognition, 61(1), 25-39.
Harlow, J. M. (1993). Recovery from the passage of an iron bar through the head. History of Psychiatry, 4(14), 274-281.
Hill, E. L. (2004). Evaluating the theory of executive dysfunction in autism. Developmental Review, 24(2), 189-233. doi:10.1016/j.dr.2004.01.001
Hill, E. L. (2004). Executive dysfunction in autism. Trends in Cognitive Sciences, 5(1), 26-32. doi: 10.1016/j.tics.2003.11.003
Hudson, J. A., Shapiro, L. R., & Sosa, B. B. (1995). Planning in the real world: Preschool children's scripts and plans for familiar events. Child Development, 66(4), 984-998.
Hughes, C., Russell, J., & Robbins, T. W. (1994). Evidence for executive dysfunction in autism. Neuropsychologia, 32(4), 477-492.
Jolliffe, T., & Baron-Cohen, S. (1999). A test of central coherence theory: Linguistic processing in high-functioning adults with autism or Asperger syndrome: Is local coherence impaired? Cognition, 71(2), 149-185. doi:10.1016/S0010-0277(99)00022-0
Joseph, R. M., Tager-Flusberg, H., & Lord, C. (2002). Cognitive profiles and social-
communicative functioning in children with autism spectrum disorder. Journal of Child Psychology and Psychiatry, 43(6), 807-821.
Kim, Y. S., Leventhal, B. L., Koh, Y. J., Fombonne, E., Laska, E., Lim, E. C., ... & Song, D. H. (2011). Prevalence of autism spectrum disorders in a total population sample. American Journal of Psychiatry, 168(9), 904-912.
Kotovsky, K., Hayes, J.R., & Simon, H.A. (1985). Why are some problems hard? Evidence from the Tower of Hanoi. Cognitive Psychology, 17, 248-294.
Kouklari, E. C., Tsermentseli, S., & Auyeung, B. (2018). Executive function predicts theory of mind but not social verbal communication in school-aged children with autism spectrum disorder. Research in Developmental Disabilities, 76, 12-24.


38
Krikorian, R., Bartok, J., & Gay, N. (1994). Tower of London procedure: a standard method and developmental data. Journal of clinical and Experimental Neuropsychology, 16(6), 840-850.
Kroncke, A. P., Willard, M., & Huckabee, H. (2016). Assessment of autism spectrum disorder: Critical issues in clinical, forensic and school settings. New York, NY: Springer.
Lemon, J. M., Gargaro, B., Enticott, P. G., & Rinehart, N. J. (2011). Brief report: Executive
functioning in autism spectrum disorders: A gender comparison of response inhibition. Journal of Autism and Developmental Disorders, 47(3), 352-356.
Lord, C., Risi, S., Lambrecht, L., Cook Jr, E. H., Leventhal, B. L., DiLavore, P. C., . . . Rutter,
M. (2000). The autism diagnostic observation Schedule—Generic: A standard measure of social and communication deficits associated with the spectrum of autism. Journal of Autism and Developmental Disorders, 30(3), 205-223. doi: 10.1023/A: 1005592401947
Lord, C., Rutter, M. DiLavore, P. C., Risi, S., Gotham, K., & Bishop, S. (2012). The Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). Torrance, CA: Western Psychological Services.
Lord, C., Rutter, M., & Le Couteur, A. (1994). Autism Diagnostic Interview-Revised: a revised version of a diagnostic interview for caregivers of individuals with possible pervasive developmental disorders. Journal of Autism and Developmental Disorders, 24(5), 659-685.
Luria, A. R., Karpov, B. A., & Yarbuss, A. L. (1966). Disturbances of active visual perception with lesions of the frontal lobes. Cortex, 2(2), 202-212.
Mangeot, S., Armstrong K, Colvin A. N., Yeates K. O., & Taylor H. G. (2002). Long-term
executive function deficits in children with traumatic brain injuries: assessment using the behavior rating inventory of executive function (BRIEF). Child Neuropsychology, 8, 271-84.
Matson, J. L., & Kozlowski, A. M. (2011). The increasing prevalence of autism spectrum disorders. Research in Autism Spectrum Disorders, 5(1), 418-425.
Mayes, S. D., & Calhoun, S. L. (2003). Analysis of WISC-III, Stanford-Binet: IV, and academic achievement test scores in children with autism. Journal of Autism and Developmental Disorders, 33(3), 329-341.
Memari, A. H., Ziaee, V., Shayestehfar, M., Ghanouni, P., Mansournia, M. A., & Moshayedi, P. (2013). Cognitive flexibility impairments in children with autism spectrum disorders: links to age, gender and child outcomes. Research in Developmental Disabilities, 34(10), 3218-3225. "
Merchan-Naranjo, J., Boada, L., del Rey-Mejias, A., Mayoral, M., Llorente, C., Arango, C., &
Parellada, M. (2016). Executive function is affected in autism spectrum disorder, but does


39
not correlate with intelligence. Revista de Psi qui atr ia y Salad Mental (English Edition), 9(1), 39-50.
Monsell, S. (2003). Task switching. Trends in Cognitive Sciences, 7(3), 134-140. doi: 10.1016/S13 64-6613 (03 )00028-7
Nouchine, H.,Volkmar, F. R., & SpringerLink (Online service). (2013) Executive functions. In: Volkmar F.R., (Eds.). Encyclopedia of Autism Spectrum Disorders. New York, NY: Springer.
Ozonoff, S., & Jensen, J. (1999). Brief report: Specific executive function profiles in three
neurodevelopmental disorders. Journal of Autism and Developmental Disorders, 29(2), 171-177.
Ozonoff, S., & McEvoy, R. E. (1994). A longitudinal study of executive function and theory of mind development in autism. Development and Psychopathology, 6(3), 415-431.
Ozonoff, S., Rogers, S. J., & Pennington, B. F. (1991). Asperger's syndrome: Evidence of an empirical distinction from high-functioning autism. Journal of Child Psychology and Psychiatry, 32(1), 1107-1122
Pavlina, H., Tomas, K., Pavla, L., Hana, O., & Martin, B. (2018). Autism, impulsivity and inhibition: A review of the literature. Basal Ganglia, 14, 44-53.
Pellicano, E. (2010). Individual differences in executive function and central coherence predict developmental changes in theory of mind in autism. Developmental Psychology, 46(2), 530.
Perner, J., & Lang, B. (1999). Development of theory of mind and executive control. Trends in
Cognitive Sciences, 5(9), 337-344.
Perner, J., & Lang, B. (2000). Theory of mind and executive function: Is there a developmental relationship? In D. J. Cohen, S. Baron Cohen, & H. Tager Flusberg (Eds.), Understanding other minds: Perspectives from developmental cognitive neuroscience (2nd ed., pp. 150-181). New York, NY: Oxford University Press.
Pickering, S. J., & Gathercole, S. E. (2001). Working Memory Test Battery for Children. London: Pearson Assessment.
Pisula, E., Pudlo, M., Slowinska, M., Kawa, R., Strz^ska, M., Banasiak, A., & Wolanczyk, T. (2017). Behavioral and emotional problems in high-functioning girls and boys with autism spectrum disorders: Parents’ reports and adolescents’ self-reports. Autism, 21(6), 738-748.
Robinson, S., Goddard, L., Dritschel, B., Wisley, M., & Howlin, P. (2009). Executive functions in children with autism spectrum disorders. Brain and Cognition, 77(3), 362-368.


40
Romine, C. B., & Reynolds, C. R. (2005). A model of the development of frontal lobe
functioning: Findings from a meta-analysis. Applied Neuropsychology, 12(4), 190-201.
Schopler, E., Reichler, R. J., & Renner, B. R. (1986). The Childhood Autism Rating Scale
(CARS): For diagnostic screening and classification of autism. New York: Irvington.
Shallice, T. (1982). Specific impairments of planning. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 295(1089), 199-209.
Shallice, T. (1988). From neuropsychology to mental structure. Cambridge University Press.
Snodgrass, J. G., & Vanderwart, M. (1980). A standardized set of 260 pictures: norms for name agreement, image agreement, familiarity, and visual complexity. Journal of Experimental Psychology: Human Learning and Memory, 6(2), 174.
Stockings of Cambridge (SOC). (n.d.). Retrieved from
http://www.cambridgecognition.com/cantab/cognitive-tests/executive-function/stockings-
of-cambridge-soc/
Trammell, B., Wilczynski, S. M., Dale, B., & Mcintosh, D. E. (2013). Assessment and
differential diagnosis of comorbid conditions in adolescents and adults with autism spectrum disorders. Psychology in the Schools, 50(9), 936-946.
Unterrainer, J. M., & Owen, A. M. (2006). Planning and problem solving: from neuropsychology to functional neuroimaging. Journal of Physiology-Paris, 99(4-6), 308-317.
van den Bergh, S. F., Scheeren, A. M., Begeer, S., Root, H. M., & Geurts, H. M. (2014). Age related differences of executive functioning problems in everyday life of children and adolescents in the autism spectrum. Journal of Autism and Developmental Disorders, 7-/(8), 1959-1971.
Van Eylen, L., Boets, B., Steyaert, J., Evers, K., Wagemans, J., & Noens, I. (2011). Cognitive flexibility in autism spectrum disorder: Explaining the inconsistencies? Research in Autism Spectrum Disorders, 5(4), 1390-1401.
Verte, S., Geurts, H. M., Roeyers, H., Oosterlaan, J., & Sergeant, J. A. (2006). Executive
functioning in children with an autism spectrum disorder: Can we differentiate within the spectrum? Journal of Autism and Developmental Disorders, 36(3), 351-372.
Williams, D. L., Mazefsky, C. A., Walker, J. D., Minshew, N. J., & Goldstein, G. (2014).
Associations between conceptual reasoning, problem solving, and adaptive ability in high-functioning autism. Journal of Autism and Developmental Disorders, 44(11), 2908-2920.
Yuan, P., & Raz, N. (2014). Prefrontal cortex and executive functions in healthy adults: a metaanalysis of structural neuroimaging studies. Neuroscience & Biobehavioral Reviews, 42, 180-192.


41
Zhang, J. (1997). The nature of external representations in problem solving. Cognitive Science, 21, 179-217.


Full Text

PAGE 1

EXECUTIVE FUNCTION DEFICITS IN ADOLESCENTS WITH AUTISM SPECTRUM DIAGNOSIS: AN ANALYSIS WITH A TOWER OF LONDON TASK b y DANA READY B.S. , Colorado State University, 2013 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Psychology School Psychology Program 201 9

PAGE 2

ii The th esis for the Doctor of Psychology degree by Dana Ready h as been approved for the School Psychology Program by M. Franci Crepeau Hobson, Chair Bryn Harris Rachel Stein Date: Ma y 18, 2019

PAGE 3

iii Ready, Dana (PsyD, School Psychology Program) Executive F unction D eficits in A dolescents W ith Autism Spectrum Diagnosis: An A nalysis W ith a Tower of London T ask. Thesis directed by Professor Franci Crepeau Hobson ABSTRACT Early identification of children with Autism Spectrum Disorder (ASD) may lead to important early intervention services that could potentially increase the quality of life for a large number of children. The purpose of this study was to examine executive functioning and planning abilities associated with ASD severity, as well as compare executive functioning and planning abilities in those identified with ASD to a normative population sample. Factors of interest included scores on the Autism Diagnostic Observation Schedule Second Edition (ADOS 2) and the Tower of London Drexel University: 2 nd Edition (TOL DX). Participants were t hirty children between the ages of 7 to 14 who were identified with ASD at a small private clinic in a large city in the western United States . D ata were c ollected via a retrospective review of records. Results o f a correlation analysis indicated that ASD severity as measured by the ADOS 2 was not significant ly associated with executive functioning and planning abilities as measured on the TOL DX. Comparison of the sample with the general population revealed significant difference s in executive functioning as indicated via scores on several TOL DX scales . Results indicate that the ASD sample had sig ni ficant deficits in executive problem solving and planning when compared with typical peers . Implications for both assessment and intervention with children with ASD are discussed. The form and content of this abstract are approved. I recommend its publication.

PAGE 4

iv Approved: M. Franci Crepeau Hobson

PAGE 5

v TABLE OF CONTENT S CHAPTER I. INTRO DUCTION 1 II. LITERATURE REVIEW 3 III. METHOD S 2 1 IV. RESULTS 2 6 V. DISCUSSION 2 8 REFERENCES 3 4

PAGE 6

1 CHAPTER I INTRODUCTION One of the most frequently encountered and studied conditions in the mental health field today is Autism Spectrum Disorder (ASD). The number of cases has risen dramatically over the last decade , and many hypothes e s have been offere d to assist with explaining this phenomen on . Today , the Center s for Disease Control report s that 1 in 59 children is identified with ASD ( Baio et al., 2018). According to Matson & Kozlowski (2011), the numbers of ASD diagnoses will continue to rise. Many authors attribute this growing prevalence to changes in diagnostic criteria , greater public awareness, and lower age at diagnosis (Matson & Kozlowski, 2011 ; Ki m et al., 2011 ). With the increase of ASD identification comes concerns regarding both identifying and meeting the specific needs individuals affected by the disorder . Common traits associated with ASD include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides (Durand, 2014). Individuals with ASD typically experience difficulty with social commun ication which limits their abilities to interpret facial expressions and can inhibit their capacities to integrate emotions with dialogue (Kronke, Willard, & Huckabee, 2016). In addition to these hallmark characteristics of ASD, r esearch suggests that chil dren with this disorder also have difficulties in a number of areas related to executive functioning including, working memory, planning, inhibition, and cognitive flexibility (Verte, Geurts, Roeyers, Oosterlaan, & Sergeant, 2006). However, research findin gs have been inconsistent in t his area perhaps due in part to the varying ways in which ASD was identified in the studies , as well as with the tools used to assess executive functioning .

PAGE 7

2 Problem and Significance There is evidence that early identification and intervention mitigates ASD risk (Kroncke et al., 2016). early intervention may prevent the manifestation of many traits associated with ASD because young child ren are still experiencing ne uro plasticity. approach , there has recently been a shift in the field to encourage early intervention for children who present with early signs of the disorder (Eapen, 2016). Consequently, assessing for easily identifiable deficits, such as those in executive functioning and planning may foster earlier intervention. Further , as ASD identification incorpora tes additional identifying features, it is important to recognize those deficits associated with ASD that are related to quality of life. Fostering the development of skills to enhance executive functioning and planning abilities through early intervention may mitigate future problems for those identified with ASD. T his research paper is guided by the following questions: 1. Are deficits in executive functions associated with planning and problem solving abilities associated with autism severity? 2. Do individuals identified with ASD have executive functioning deficits measured by the TOL DX in comparison to the normative sample in the following areas : executive problem solving and planning, behavioral inhibition and impulse control, cognitive flexibility, abstract/conceptual reasoning, rule governed behavior, and monitoring ?

PAGE 8

3 CHAPTER II LITERATURE REVIEW Autism Spectrum Disorder In 1943, Leo Kanner first described 11 children who displayed isolated and repetitive behaviors. The following year, Hans Asperger described a group of children who demonstrated impaired social interactions and perseveration on se lect interests. Kanner and Asperger were both Austrian ( Barahona Corrêa & Filipe, 2016) Dementia Praecox or the Group of Schizophren ias writings ( Barahona Corrêa & Filipe, 2016). Autism Spectrum Disorder (ASD) was originally thought to result from a lack of affection from parents or guardians and was formerly characteriz ed as a form of childhood schizophrenia. Today, however, we know this not to be true (Barna, 2017). ASD is a neurodevelopmental disorder that affects how an individual perceives social situations and the world around them. Common traits associated with AS D include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides (Durand, 2014). Individuals with ASD typically experience difficulty with social communication which limits their abili ties to interpret facial expressions and can inhibit their abilities to integrate emotions with dialogue (Kronke, Willard, & Huckabee, 2016). Both male and female adolescents diagnosed with ASD have been found to have increased levels of behavioral and emo tional problems in comparison to their same aged peers (Pisula et al. , 2017.) In the late ,

PAGE 9

4 average intelligence or Tang, & Thomas, 2013, p. 1504). Currently, those who meet the criteria for high functioning ASD are overrepresented in research and are becom ing increasingly common in clinical evaluations, even though high functioning ASD it is not recognized in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM 5; American Psychological Association [APA], 2013). An ASD diagnosis do es not depend on intellectual ability and the severity of the disorder can be equ ivalent across levels of IQ (Joseph, Tager Flushberg, & Lord, 2002) ; however, 46% of individuals diagnosed with ASD have average or above IQs (Trammell et al., 2013). Higher i ntelligence in individuals with ASD is associated with a greater plasticity, meaning these individuals have a greater potential to mitigate common ASD presentations (Kronke et al. , 2016). Not surprisingly, individuals with higher IQs are often diagnosed wi th ASD at a later age than those with lower IQs (Mayes, & Calhoun, 2003). Those individuals with higher IQs who are diagnosed with ASD are likely to show greater benefit from intervention due to a greater cognitive capacity and the ability to respond to di fferent types of therapeutic interventions (Kronke et al. , 2016). Executive Functioning The last part of the brain to mature is also the largest anatomical part of the brain, the frontal lobes. According to Hadjikhani and Volkmar (2013), typically, the fr ontal cortex does not corresponding functions: Frontal operculum : language, mirror mechanisms. Precentral : Motor. Dorsolateral prefrontal : executive functions. Orbitofront al/ventromedial : emotion, decision

PAGE 10

5 making, response inhibition. Anterior cingulate : choice selection, reward, social emotion, In 2014, Yuan and Raz studied the relationship between prefrontal cortex size and execu tive functioning ability in adults. The researchers found significantly better performance on executive functioning tests in those with a larger prefrontal cortex. There have been no differences found in the orbitofrontal cortex of individuals diagnosed wi th autism, but recent studies have found enlarged cerebral white and gray matter in toddlers diagnosed with autism, especially in the frontal, temporal, and cingulate cortices (Hadjikhani & Volkmar, 2013). Additionally, some research indicates that childre n diagnosed with autism have more neurons in the prefrontal cortex, a larger prefrontal cortex, and abnormalities in the inferior frontal gyrus, as well as differences in the cortical thickness of the inferior frontal cortex (Hadjikhani & Volkmar, 2013; Co (2004) determined that children diagnosed with ASD undergo abnormal brain development in their first four years of life. Specifically, study results indicated abnormally accelerated brain growth during the first two years of life, and then a decrease in the rate of development and even a complete lack of growth in some structures. This aligns with the theory of brain overgrowth in the first years of life for individuals identified with ASD, which is associated with deficits in executive functioning (Courchesne et. al., 2010) . cognitive, and emotional self p. 1). The connection between a compromised frontal lobe and deficits in executive functioning between frontal lobe lesions and difficulty completing complicated activities (Bianchi &

PAGE 11

6 Macdonald , 1922). Building on Bianc (1966) proposed that complex processes underlie certain types of disorders, particularly those associated with damage to the frontal lobes. Similarly, Shallice (1988) described the frontal cortex as being essential for the planning of act ions to take in the future. I nterconnected with other cortical and sub cortical structures, the prefrontal cortex has been credited with highly complex and multifaceted functions. Some would argue that the frontal lobe is what separates us from other mamma ls and provides us with our individuality and the ability to partake in higher order thinking and processes that help us attain goals (Unterrainer & Owen, 2006). The relationship between cognition and emotion , as well as the awareness of executive functio ning and its location in the brain was brought to light in the mid nineteenth century with the case of Phineas Gage. According to the Encyclopedia Britannica, due to a construction accident, Gage had a railroad tamping rod shot into his head, going through his brain and causing significant frontal lobe damage. Gage survived this accident and was even conscious and able to speak, but was found to be more impulsive, unkempt, crude, and irresponsible ( Gearhart , 2018; Goldstein & Naglieri, 2013). Although an un explainable anomaly at the time, we now the affective components of cognitive processing and executive functioning abilities . More specifically , Gauge was prone to making poor decisions and exhibiting mal adaptive behaviors when compared to his previous behavior, even though his cognitive ability seemed relatively intact (Goldstein & Naglieri, 2013). The idea and conceptualization of executive functioning developed out of the observation of individuals who have changed due to frontal lobe damage. Groups of these individuals were observed by Luria and labeled as having dysexecutive syndrome. These indiv iduals were able to perform within average ranges when undergoing cognitive assessments but were disorganized in

PAGE 12

7 their everyday tasks and strategies (Goldstein & Naglieri, 2013). Today, we know that executive functioning is necessary to engage in healthy a daptive behavioral choices, and includes the processes of working memory, problem solving, planning, self monitoring, self motivation, and interference control (Goldstein & Naglieri, 2013). Executive Functioning and ASD In order to engage in healthy adapti ve behavior in the real world, one must be capable of a constant exchange between both emotional and cognitive processes. An individual with inhibited cognitive flexibility has trouble with making adjustments based on feedback (Bacso & Nilsen, 2017). Hughe s, Russell, and Robbins, consider executive functioning to be an umbrella (1994, p. 477). These skills are typically associated with the frontal lobes, which are often implicated in individuals with ASD. Freeman, Locke, Rotheram Fuller, and Mandell (2017) found that children with poorer executive functioning demonstrat ed increas ed playground isolation and less engagement with peers. Damasio and Maurer (1978) suspect that the core of ASD symptoms might be executive functioning deficits. This may be associated with the unique structure of the frontostriatal neural network, which ma y lead to a lack of control when dealing with situations that are uncertain, difficult, or even situations that occur daily. (Goldstein & Naglieri, 2013). Individuals identified with ASD have impacted synchronization between the frontal and posterior regions of the cortex which is observable on a broad range of executive functioning measures (Goldstein & Naglieri, 2013 , p. 123 ). Research suggests that children with ASD have difficulties in a number

PAGE 13

8 of areas related to executive functioning including working memory, planning, inhibition, and cognitive flexibility (Verte, Geurts, Roeyers, Oosterlaan, & Sergeant, 2006). Working memory is an extremely influential executive function as it can impact all other executive functions. In order to acc ess working memory, an individual must be paying attention ; and more specifically, one must attend to the correct information while simultaneously ignoring other unimportant stimuli (or practicing inhibition). In addition , the individual must be flexible a nd have the ability to s hift between visual and verbal stimuli to process information. Finally, when using working memory, one must be able to track and choose to what information to react (Goldstein & Naglieri, 2013). Typically , individuals with ASD exper ience deficits in working memory due to associated executive functioning deficits, such as cognitive flexibility or planning. (Goldstein & Naglieri, 2013). The ability to problem solve was first proposed by Alexander Luria (1973) as a cognitive ability for matted from "intention formation, planning, and programming" (Goldstein & Naglieri, 2013, p. 294). Kotovsky et al. (1985) found that when administered a measure of executive functioning called the Tower of Hanoi, participants use d two different problem sol ving techniques that relate to two different cognitive processes . The first, referred to as 'exploratory behavior', refers to those who make random moves that could being the subject closer or further away from the intended goal. The second phase is called 'final path behavior' and refers to the recognition from the participant that there is a final sequence of moves that can be done to achieve a goal (Kotovsky et al., 1985). In alignment wi th Kotovsky et al. (1985), Zhang (1997) argues that the two phases represent different cognitive processes ; therefore , clinical and developmental abilities may contribute to differences in problem solving abilities. Consistent with this theory, Berg and By rd (2002) studied the lengths of the separate phases with a similar

PAGE 14

9 test, the Tower of London ( TOL ) , and found that scores are sensitive to age and testing manipulations in younger populations. Although for most people there is a clear relationship betwe en adaptive functioning, conceptual reasoning, and problem solving, Williams et al. (2014) believe that this relationship is different for individuals identified with ASD. Research suggests that while those identified with ASD have the ability to implicitl y learn, utilizing a flexible response to novel problems may be a contributing factor to problem solving difficulties for those identified with ASD (Williams et al., 2014). etween 5 diagnostic criteria f or ASD are stereotypic and repetitive behaviors, as well as inflexibility in social and communication domains. Although there have been inconsistent findings in the relationship of cognitive flexibility and an ASD diagnosis, it is believed that a number of variables contribute to limited flexibility in those identified with ASD ( Goldstein & Naglieri, 2013). These include a limited capacity to process new information , a lack of explic it instructions and/or predictability, and high working memory load. Planning is the most consistent executive functioning domain found to be impaired in those identified with ASD. Planning involves several steps, and each step not only has to be stored, but possibly adjusted ( Goldstein & Naglieri, 2013) . Planning abilities change and become , with children between the ages of 5 and 8 showing the greatest development and improvement in planning abilities (Romine & Reynolds, 2 005) . Hudson et al . (1995) discovered that young children around the age of three were able to use verbal abilities to plan for familiar tasks. This simple planning is more common in extremely young children. According to Levin et al . (1991) , children between the ages of 7 and 11 a re able to utilize

PAGE 15

10 reasoning abilities and implement strategic behaviors that lead to competent and organized planning. Planning skills become more adult like as children approach adolescence . Anderson et al . (2001) found that between the ages of 9 the TOL test. Bennetto, Pennington, and Rogers (1996) used the Tower of Hanoi to assess the planning and problem solving abilities in 11 24 year olds identified with ASD via the Childhood Autism Rating Scale (CARS; Schopler, Reichler, & Renner, 1986). In comparison to the control group, those identified with ASD performed more poorly in terms of efficiency and they made more perseverative responses. In their study uti lizing the Tower of Hanoi, Ozonoff and Jensen (1999) recruited forty 6 18 year olds identified with ASD through the ADI R (Lord et al., 1994) and Autism Diagnostic Observation Schedule (ADOS; Lord et al., 1989). They found those identified with ASD to have deficits in executive functioning associated with flexibility and planning. Elizabeth Hill (2004a) critically reviewed the various foundational studies discussed above to find trends in executive functioning abilities in those identified with ASD. Hill f ound specific deficit in planning in relation to normally developing individuals and those with other disorders not ndings occurred with standard executive functioning assessments (e.g., Tower of Hanoi and Stockings of Cambridge), as well 2004, Hill published an article that exp anded on her initial review of executive functioning abilities in those identified with ASD (Hill, 2004b). In this article, Hill specified that those identified with ASD were impaired in planning compared to the control groups, but this was only evident on puzzles that require a longer sequence of moves. Additionally, those with ASD had

PAGE 16

11 greater success with the executive function of planning when they had a higher non verbal mental age. This indicates that ASD might lead to an executive functioning deficit in planning but having a learning disability may also be a contributing factor (Hill, 2004b). According to Robinson et al (2009), c hildren identified with ASD and those with IQ scores in the lower limits of the average range have impaired planning abilities. Happé et al. (2006) found that those identified with ASD did not encounter the same difficulties on executive functioning measures as their normative comparison group . In this study, the researchers used a customized compu terized executive functioning assessment that told participants what number of moves would allow them the total correct score for the prompt . Additionally, i t encouraged participants to not make any moves until they had planned and could solve the solution in the correct number of moves. These adaptations and others made by Happé et al. (2006) may account for the difference in findings. Inhibition is another area implicated in executive function deficits in individuals with ASD as they have been found to have trouble ignoring or suppressing irrelevant or interfering information. ( Goldstein & Naglieri, 2013). According to Friedman & Miyake (2004), inhibition consists of prepotent response inhibition, resistance to distractor inte rference, and resistance to proactive interference. P repotent response inhibitions usually present themselves as an urge or impulse to engage inappropriate behavior and having an appropriate inhibition control means s in order to perform socially appropriate, and therefore Adams & Jarrold, 2012, p. 12). According to Friedmand and Miyake (2004), resistance to distractor interference relates to the capacity to ignore distractions in the external e nvironment that are unrelated to task completion. This process relates to selective attention skills and is vital to completing any complex task. Resistance to proactive interference

PAGE 17

12 relates to the ability to ignore or resist memor ies or information that is no longer relevant to the task (Friedmand & Miyake, 2004). This may seem similar to the resistance to distractor interference, but in resistance to proactive interference, the information that may cause interference was previously rele vant to the task and is available before the target information is available (Friedmand & Miyake, 2004 ). Through meta analysis, Pavina et al. (2018) found inconsistent findings in terms of ASD and inhibition , but concluded that those identified with ASD generally have some inhibitory deficit. Many of these inhibitory deficits were due to inattention rather than specified traits associated with ASD (Pavina et al., 2018). Memari and colleagues (Memari et al., 2013) e xamined the relationship between the cognitive flexibility patterns and demographics of children aged 7 14 years old identified with S yndrome, and P ervasive D evelopmental D isorder not otherwise specified (PD NOS) through both the DSM IV (A merican Psychiatric Association, 2000) and the A utism D iagnostic I nterview R evised (ADI R ; Lord, Rutter, & Le Couteur, 1994 ). The measure used to examine executive functioning abilities was the Wisconsin Card Sorting Test ( WCST ; Kongs, Thompson, Iverson, & Heaton, 2000 . The parents of participants completed a background information form that gathered demographic information including parent education level, child age, gender, weight and height, education (grade level), medical history , and current medications Their results demonstrated that gender, not age, was best associated with cognitive flexibility ability in those identified with ASD (Memari et.al., 2013) . Although gender wa s not always significantly related to performance when confounding fa ctors are accounted for on the WCST, this finding align s with Lemon e t a . l (2001) who indicate d there might be different behavior and cognitive profiles for girls and boys identified with ASD.

PAGE 18

13 Van Eylen et.al. (2011) investigated the cognitive flexibility of children identified with ASD. The authors developed a task similar to the WCST, but with more task switching variants. This variant needed additional disengagement to accomplish an appropriate switch and had a lowe r degree of instruction prior to task initiation. This resulted in all participants to have slower switching and to respond more slowly . On this WCST variation, those children identified with ASD had an increased switch cost when compared to their neurotyp ical peers. Additionally, those identified with ASD made more perseveration errors, though not to a significant degree. Similar to other research, f indings from this study indicate that those identified with ASD have a difficult time with cognitive flexibi lity . Merchan Naranjo et.al. (2016) examined the executive functioning of patients identified with high functioning ASD . Specifically, the researchers examine d performance on a range of subtests from various neurological assessment . A comparison of the scores of the ASD group with those of healthy controls revealed significant difference s demonstrat ing deficit s in a number of executive functions, including attention, working memory, mental flexibility, problem solving, and inhibitory control. These results indicate that despite having an IQ score within the Average range, participants in the ASD group still struggle with executive functioning impairments. Chan et.al. (2009) looked at the executive dysfunction associations in children identified with ASD between the ages of 6 14 through the administration of the Test of Nonverbal Intelligence 3 rd edition ( Toni III ; Brown et al., 1992), th e Rey Osterrieth Complex Figure Test (Rey O; Bernstein and Waber, 1996), Hong Kong List Learning Test 2 nd edition (HKLLT; Chan, 2006), Object Recognition Test (OR ; Snodgrass and Vanderwart, 1980 ), and Conners Continuous Performance Test II (CPT II; Conners, 2000). Resul ts showed those identified with

PAGE 19

14 ASD had higher levels of Intrusion, Delayed Intrusion, and False Alarms on the HKLLT, as well as higher levels of False Alarms on the OR , all of which are indicative of executive function deficits . On the CPT, the scores of students identified with ASD had such high levels of omission errors their data could not be included in the study. Th ese numerous omission errors may have been due to participants not following the instructions. Similar to the Merchan Naranjo et.al. (2016 ) study, a nalyses indicated that the significant differences were due to the ASD identification and were not related to IQ ( Chan et al., 2009) . ASD Theories Although deficits in executive functioning seemingly align with an ASD identification, ASD cannot be defined as something that arises due to executive functioning deficits (Geurts, Corbett, & Solomon , 2009) and th e relationship is far from straight forward . Since ASD is a spectrum that represents a collection of heterogeneous disorders (Geurts et al., 2009) , study findings can be inconsistent. In addition, measurement concerns and methodological differences have als o contributed to inconsistencies in results (Geurts et al., 2009) . Even within defined demographics, there are still considerable differences in executive functioning abilities for those identified with ASD ( Goldstein & Naglieri, 2013). Due to these incons istencies, no single theory of ASD has emerged; instead , there are several dominant ASD theories , including C entral C oherence T heory and Theory of Mind (ToM). Frith (1989) found that those identified with ASD experienced difficulty with context in spoken language and described this phenomena as cited in Jolliffe & Baron Cohen, 1999, p. 149). In this theory, those identified with ASD have trouble attending to large patterns or global pieces of information and instead intensely focus on smaller pieces of

PAGE 20

15 information with weak central coherence. (Jolliffe & Baron Cohen, 1999). This theory emphasizes the cognitive processing or executive functioning aspects of ASD . Boyd et. al. (2009) examined the relationship among the triad of clinical symptoms outlined in the DSM IV for those identified with ASD, which inc ludes restricted and repetitive behaviors, communication deficits , and social impairments. Using scores from the Behavioral Regulation Index of the Behavior Rating Inventory of Executive Function ( BRIEF ; Gioia, Isquith, Guy, & Kenworthy, 2000) correlated with repetitive behaviors and the clinical expression of these behaviors, Boyd et.al. (2009) demonstrated that executive functioning deficits are not the underlying reason explanation for sensory features associated with ASD. These findings are contrary to Central Coherence Theory and suggest that something else underlies this aspect of ASD. The ToM model e xam ines the perspective of those identified with ASD and suggests that they have difficulty understanding the minds of those around them. Mor e specifically, the ability to for the social and communicative characteristics often associated with ASD ( e.g., limited eye contact, echolalic languag e , etc; Fl etcher, McConnell, Manola, & McConachie, 2014). Pellicano (2010) conducted a longitudinal study assessing the relationship of the ToM, executive function, and central coherence in 37 children identified with ASD over the course of three years. She found th at at the time of the intake, executive function and central coherence abilities were predictive longitudinally of change s in ToM performance , and these changes were independent of age, language, nonverbal intelligence, and early ToM skills (Pellicano, 2010). Consistent with Boyd et al (2009, Pellicano found no links between executive functioning and central coherence and their presenting co occurring abnormalities in those identified with ASD were independent of each other. Although t he relationship between executive functions and central coherence has

PAGE 21

16 not been thoroughly examined , i t is believed that the central coherence theory and executive functions relate to diffe rent aspects of the ASD spectrum (Goldstein & Naglieri, 2013). Kouklari, Tsermentseli, and Auyeung (2018) used cross sectional data obtained from children aged 8 12 identified with ASD to assess the association of executive functioning and ToM. Participant s were administered subtests from the Delis Kaplan Executive Function System (D KEFS; Delis, Kaplan, & Kramer, 2001) including S orting T est and W ord/ C olor I nterference. Additionally, participants were administered working memory digit recall and backwards digit recall (WMTB C; Pickering & Gathercole, 2001), Reading the Mind in the Eyes ( C V ersion; Baron and the Social Responsiveness Scale second edition (SRS 2; C onstantino & Gruber, 2012). Results demonstrated that executive functioning and ToM were selectively correlated to a significant degree when controlling for age and IQ. Additionally, working memory predict ed ToM in both the control group and participants i dentified with ASD. Ozonoff, Rogers, and Pennington (1991) compared the neuropsychological profiles of 23 individuals aged 8 (AS) . Through re analysis of data from a former paper, th e authors were able to separate the larger autistic sample into an HFA and an AS group based on scores on neuropsychological measures (Ozonoff et al., 1991). These neuropsychological profiles included the Tower of Hanoi as an executive functioning measure, as well as assessments that evaluated neuropsychological, intellectual, and social cognitive domains. They found that compared to each other and the control group, the HFA group had the largest impairment in executive functioning, ToM composites, and emot ional perception (1991). These results align with Ozonoff and (1994) findings in a longitudinal study of 10 23 year olds. This study examined the ToM ability

PAGE 22

17 and executive functioning development over a 3 autistic adolescents with learning age, IQ, gender, and socioeconomic status (SES). One assessment used to assess executive functioning was the Tower of Hanoi. Findings from this longitudinal stud y indicated that in those identified with ASD, both executive functioning and ToM abilities failed to improve with development (Ozonoff & McEvoy, 1994). These results suggest that those with impacted executive functioning abilities may never reach appropri ate functional levels and these impairments are lifelong associations with ASD. Although research has demonstrated that individuals with ASD do have impairments consistent with ToM , they also have impaired performance on tasks that do not require the functioning closely align and participants are required to conceptualize (i.e., infer) what th e experimenter wants them to do on most executive functioning tasks (Goldstein & Naglieri, 2013). Frye et al. (1996) argued that executive functioning abilities are necessary to perform many ToM tasks, while Perner and Lang (1999, 2000) believe that the sk ills necessary in the ToM model are required for the development of executive functioning. While t he exact relationship between executive functioning and ToM in ASD is unclear, research has demonstrated that training executive functioning abilities in chil dren with ASD seems to improve their performance on ToM tasks, whereas ToM training is not associated with improved executive functioning (Goldstein & Naglieri, 2013). It is speculated that this is because executive function may be a precursor to To M or be cause the ToM is essential to executive control of action (Fisher & Happé , 2005). According to Goldstein and Naglieri (2013 ) , t he consensus is that

PAGE 23

18 ToM and executive functioning abilities develop alongside each other and interact and both are impacted in t hose identified with ASD. Although there is general consensus that individuals with ASD have various deficits in executive functioning (Hadjikhani, 2013) , ASD is not described as an executive functioning disorder. This is because executive functioning deficits are not specific to those identified with ASD, as such deficits are associated with other disorders such as Attention Deficit Hyperactivity Disorder (ADHD; Goldstein & Naglieri, 2013) and not every person identified with ASD has executive functioning deficits. It is now hypothesized that ASD results from a complex interaction of cognitive deficits and/or styles such as ToM, with no single deficit suff icient or required for the diagnostic profile (Goldstein & Naglieri, 2013). According to Hadjikhani (2013), although there is no consensus in the field regarding the need to assess executive functioning abilities in ASD, additional research in this area i s warranted to determine those processes that may contribute to ASD identification (Goldstein & Naglieri, 2013). Further, research examining performance on traditional tasks is warranted as individuals with autism have been found to perform better on compu ter administered neuropsychological assessments of executive functioning than those administered by humans (Goldstein & Naglieri, 2013) . The Tower of London task as an Assessment of Executive Functioning Shallice developed the original Tower of London (TOL) task to assist with identifying frontal lobe and planning processes deficits. It was considered an adapted and simplified Tower of Hanoi test, but had problems that increased in difficulty (Krikorian, Bartok, & Gay, 1994). The TOL task requires the individual to move three different colored beads around three prearranged pegs to match a pattern established by the examiner. Each peg hold s one to three beads. After the examinee is shown their designated board and t

PAGE 24

19 board, they are then asked to make their board look like the demonstration board in as few moves as possible (Culbertson & Zillmer, 2005). After this, the two rules of the TOL task are introduced: participants may only plac e as many beads on a peg as a peg will allow ( the first peg can hold up to three beads, the second peg up to two beads, and the third peg can hold only one bead) ; and only one bead may be moved at a time. The administrator copies the bead and peg patterns from the TOL task protocol and keeps track of the following scores : Total Moves, Rule Violations, Time Violations, Initiation Time, and Execution Time. Each pattern becomes progressively more difficult, in part due to having only the three available pegs t o rearrange the beads. The Tower of London Drexel University (TOL DX) was created by William C. Culbertson and Eric A. Zillmer in 1998. A revision and publication of a second edition was published in 2005. Although the TOL DX is similar to the original TO L, the TOL DX has & Zillmer, 2005, p. 1). The authors of the TOL DX task created eigh t variables whose scores represent (Culbertson & Zillmer, 2005) . The specific abilities assessed by the TOL DX include impulse control and behavioral inhibition , cognitive flexibility, executive problem solving and planning, working memory, cognitive flexibility, abstract/conceptual reasoning, rule governed behavior, and monitoring. The authors acknowledge that there is still much relate d to the precise cognitive processes underlying the TOL DX that is not understood; however, research suggests that the TOL DX

PAGE 25

20 (Culbertson & Zillmer, 2005, p. 25). A number of these cognitive computations align with executive functions, which are thought to be processed in the frontal lobes of the human brain. Individuals identified with ASD have reported to have impaired abilities across this task. Robinson, Goddard, Dritschel , Wisley, and Howlin (2009) conducted a study with 108 children aged 8 17 to compare TOL DX performance in children with and without ASD . ASD identification was made according to the Social Communication Questionnaire (SCQ), a 40 item parent checklist from the Autism Diagnostic Interview Revised (ADI R; Lord et al., 1994). The researchers found that participants with ASD performed worse on the TOL DX and there was an increase in the number of violations made, indicating impairment in planning difficulties. Their findings also demonstrated a significant positive correlation between rule violations and age. Studies examining executive functioning in children with ASD have resulted in inconsistent findings, making it difficult to determine the neuropsychological profile of these individuals. The lack of consistent results may be due in part to methodological d ifferences in studies, including when, where , and how ASD was diagnosed, as well as how executive functioning was assessed. The present study expands and improve s upon research in this area by including participants who have been formally diagnosed with ASD by qualified professionals in a community based clinic and by using a performance based measure of executive functioning that requires the individual to utilize internal controls. This study aims to identify the relationship bet ween an ASD identification and deficits in executive functioning as measured by the TOL DX.

PAGE 26

21 CHAPTER III METHODS Participants Participants were identified through a record review at a small private clinic in a large city in the w estern United S tate s . Records for clients evaluated from January 1, 2016 to August 1, 2018 were reviewed . Inclusion criteria included meeting the diagnos tic criteria for ASD as defined by DSM V (APA, 2013) and completed intake information. Participants with n eurological disorders that present at birth were not considered for this analysis due to the potential impact on executive functioning abilities. Stud y p articipants consisted of eight females (27%) and 22 (73%) males between the ages of 7 years, 8 months and 14 years, 3 months. Ten of the participants had a sole ASD identification. Eight of the participants had one additional diagnosis ( generalized anxiety disorder, Attention D eficit/ H yperactivity D isorder (ADHD) predominantly inattentive presentation , ADHD combined presentatio n , major depressive disorder, developmental coordination disorder, specific learning disorder with impairment in reading , or persistent depressive disorder with anxious distress ) Eight participants were identified with ASD and two additional diagnos e s , whi le t wo of the participants had a primary identification of ASD and three additional diagnos e s . Ethnicity was not consistently documented at the private clinic and therefore was not considered in this study. Measures The Autism Diagnostic Observation Schedule, Second Edition (ADOS 2; Lord, Rutter, DiLavore, Risi, Gotham, & Bishop, 2012 semi structured , standardized assessment of social interaction, communication, play, and imaginative use of materials for individuals suspected of hav 2

PAGE 27

22 estimate diagnosis, internal consistency, and interrater reliability wit hin domains (Gotham , Risi, Pickles, & Lord, 2007; Lord et al. 2000). There are four 30 minute modules. Module selection is 2 of orch estrated social interactions to be scored (Gotham, Pickles, & Lord, 2009, p. 693). The examiner then introduces an assessment of behavioral items that assess social affect, restricted repetitive behaviors, and other common ASD traits through observation an d interview. These are assessed using a 4 rmality . algorithm for each module; these items are summed and compared to thresholds, which results in . Higher scores on the ADOS 2 I are an indication that an individual has a greater severity of impairment on items representing core indicators associated with ASD ( Gotham et al. , 2009). ADOS 2 O verall T otal S cores have been used to measure ASD severity, but because the module selection and assessment is heavy on verbal language abilities, it is possible that an individual could have a score change with a ta rgeted intervention (Gotham et al. , 2009). The Tower of London Drexel (TOL DX ; Culbertson & Zilmer, 1998 ) is a modified Tower of London (TOL; Shallice, 1982) used to assess childhood executive functioning. The original TOL was created to assess executive planning through the integration of cognitive and neuropsychological science . Shallice (1982) discovered scores on the TOL were independent of spatial problem solving abilities and intelligence levels. Additionally, Shallice (1982) noted that pat ients with anterior and/or posterior cerebral lesions had difficulty with different facets of executive planning measured by the TOL, including taking a longer time to decide on an initial

PAGE 28

23 move, as well as taking a longer time overall to solve the problem (Culbertson & Zilmer, 1998). The TOL DX was created by Culberts on and Zillmer (1998) and is considered a comprehensive measure of problem solving and executive planning. It was found to have acceptable preliminary reliability and validity . The TOL DX con sists of ten prompts which increase in difficulty. The examinee is expected to match the presented formation by moving three colored beads on three pegs. The examinee is shown a prompt and timed while they attempt to recreate the visual prompt on their boa rd. The e xaminer monitors the activity of the examinee and when the prompt is completed , records a number of functioning abilities . TOL DX Scores include Total Moves Score, Total Correct Score, Total Rule Violation Score, Total Time Violation Score, Total Initiation Time Score, Total Execution Time Score, and Total Problem Solving Time Score. R aw scores are converted into standard scores with a mean of 100 and a standard deviation of 15 . The standard scores are computed such that a higher numerical value corresponds with better performance (fewe r moves and rule violations, more correct items, and less time utilized), The one exception is on the Total Initiation Time Score. This standard score is computed so that a higher score reflects a longer initiation time or poorer performance . The neuropsyc hological factors associated with the TOL DX scores include executive problem solving and planning, behavioral inhibition and impulse control, attentional allocation, cognitive flexibility, abstract/conceptual reasoning, rule governed behavior, and monitor ing (Culbertson & Zilmer, 1998). The TOL DX 2nd edition was published in 2001 and featured an additional score for older adults, a s well as expanded normative data to include children and adults in age from 7 80 years old (Culbertson & Zilmer, 2005 ).

PAGE 29

24 Procedure In order to identify participants who met inclusion criteria for the study , a review of evaluations was conducted at the private clinic . If the clinical evaluation battery included the TOL DX and an ASD identification, then the record was pulled and reviewed. Files were collected alphabetically and reviewed to see if a psychological report was present in the file. If a psychological evaluation was present, then the next step was to determine if the record aligned with inclusion criteria. If the r ecord did meet the inclusionary requirements, then the record was reviewed and the d e identified data was recorded onto a password protected server. Predictor variables were coded using dummy variables. For example, those identified with ASD and generaliz ed anxiety disorder were coded as 1 (ASD) and 2 (generalized anxiety disorder). Total age of participants was recorded and converted into months. For example, a participant whose age was 7 years and 8 months at the time of testing was coded as 92 months for analysis. All scores from the ADOS 2 and TOL DX were recorded for analysis. Data Analyses Correlation al analyses were conducted to investigate the Research Question 1: Are deficits in executive functions associated with planning and problem solving abilities that are associated with autism severity ? Specifically, c orrelation s were run examining the relationship between ADOS 2 Overall Total Score and ADOS 2 Comparison Scores and TOL DX scores ( Total Move Score (TMS; sum of all moves, above the minimum required, in all ten trials) , Total Correct Score (TCS; trials out of 10 that are completed using fewest moves possible) , Total Rule Violation Score (RVS; number of times test rules are violated) , Total Time Violation Score (TTV; number o , Total Initiation Time Score (IT; total time taken in each trial before making first move) , Execution Score ( ET; total time from the

PAGE 30

25 first move to completion of each trial), and T o tal Problem Solving Score (PST; total time taken for each trial) , ) . as used to determine if there were significant correlation s among the variables. One Sample T Tests were conducted to investigate Research Question 2: Do individuals identified with ASD have executive functioning deficits measured by the TOL DX in the following areas; executive problem solving and planning, behavioral inhibition and i mpulse control, cognitive flexibility, abstract/conceptual reasoning, rule governed behavior, and monitoring in comparison? The dependent variables were TOL DX scores ( TMS, TCS, RVS, TTV, IT, ET, PST ) . These analyses compared the TOL DX scores of the study sample with those of the normative sample.

PAGE 31

26 CHAPTER I V RESULTS Thirty participants met the inclusion criteria for the study . E ight participants were female (27%) and 22 were male (73%) . They ranged in age from 7 to 14 years ( Mean=9 years , 9 months ; 11 7.7 months) . ADOS 2 and TOL DX Scores are presented in Table 1. Table 1 Age, Gender, ADOS 2 scores, and TOL DX Scores N Minimum Maximum Mean Standard Deviation Age (months) 30 85 171 117.70 22.01 ADOS II Overall Total Score 30 6 24 15.53 4.09 ADOS II Comparison Score 30 3 10 8.47 1.66 TOL DX Total Move Score 30 60 114 87 14.59 TOL DX Total Correct Score 30 2 132 88.33 21.40 TOL DX Total Rule Violation Score 30 60 108 80.93 20.96 TOL DX Total Time Violation Score 30 60 118 94.93 18.66 TOL DX Total Initiation Time Score 30 84 150 99.47 12.84 TOL DX Total Execution Time Score 30 60 118 95.60 15.95 TOL DX Total Problem Solving Time Score 30 60 118 95.87 15.99 Autism Severity and Executive Functioning Pearson c orrelation s were run to examine the association between autism severity and executive functioning as measured by the TOL DX. N one of the TOL DX scores w ere significantly correlated with ADOS 2 I Total Score s . Th ese findings indicate that deficits in executive functioning are not related to autism severity. Executive Functioning and ASD Diagnosis

PAGE 32

27 A One Sample T Test average score s differed signifi cantly from th at of the normative sample (M=100) . Assumptions were checked and met. The study sample earned significantly lower Total Move S cores ( TMS; M= 87 , SD= 14.9 ) than the general population, t (29) = 4.88 () , p<.05. Additionally, Total Correct Score (TCS) was significant ly lower (M= 88.33 , SD= 21.4 ) , t (29) = 2.99, p<.05. Finally, the study sample earned significantly lower Total Rule Violation Score s ( TRV; M= 80.93 , SD= 20.96 ) t (29) = 4.984, p<.05. No other significant differences in TOL DX scores were observed. Table 2 displays descriptive statistics for the TOL DX scores. Table 2 D escriptive statistics for TOL DX (n=30) Outcome Mean SD TOL DX Total Move Score* 87 14.59 TOL DX Total Correct Score* 88.33 21.40 TOL DX Total Rule Violation Score* 80.93 20.96 TOL DX Total Time Violation Score 94.93 18.66 TOL DX Total Initiation Time Score 99.47 12.84 TOL DX Total Execution Time Score 95.60 15.95 TOL DX Total Problem Solving Time Score 95.87 15.99 * P< 05

PAGE 33

28 CHAPTER V DISCUSSION Autism Spectrum Disorder (ASD) is a highly prevalent devel opmental disability with 1 in 59 childre n identified with the disorder in 2014 ( Baio et al., 2018). Individuals with ASD present with deficits in social communication and social interaction and restricted, repetitive patterns of behavior, interests, or activities (APA, 2013). In addition to these hallmark characteristics of ASD, research suggests that c hildren with this disorder also have difficulties in a number of areas related to executive functioning including, working memory, planning, inhibition, and cognitive flexibility (Verte et al. , 2006). However, research findings have been inconsistent int h is area perhaps due in part to the varying ways in which ASD was identified in the studies, as well as with the tools used to assess executive functioning. The purpose of this study was to examine the relationship between A utism Spectrum Disorder (A SD ) identification and executive functioning abilities . S pecifically , the study sought to investigate if ASD severity is associated with planning and problem solving abilities . Additionally, the study aimed to determine if individuals identified with ASD have deficits in executive functioning abilities as measured by an objective, performance based measure: the Tower of London Drexel University ( TOL DX ) when compared with the normative sample . Participants were 30 children ages 7 14 who were identified with A SD via a comprehensive evaluation conducted by a qualified professional. A correlation analysis found no significant relationships among the TOL DX scores and ADOS 2 Total scores, indicating that ASD severity was not related to deficits in executive functioning as measured by the TOL DX. This finding i s

PAGE 34

29 consistent with previous research that examined this relationship using executive functioning rating scales ( van den Bergh, Scheeren, Begeer, Koot, & Geurts, 2014). When comparing the average scores of the normative sample on the TOL DX to ASD sample , several significant relationships were found, including; Total Move Score (TMS) , Total Correct Score (TCS) , and Total Rule Violation Score (RVS) , with the study sampl e earning significantly lower scores on each of these scales . The TOL DX scales are measures of executive problem solving, planning, and impulse control (Culbertson & Zillmer, 2005). These results indicate that individuals with ASD have deficits in each of these areas. Robinson, Goddard, Dritschel, Wisley, and Howlin (2009 ) found similar results when assessing children identified with ASD with the TOL DX. Their study found that childre n with ASD used significant ly more moves to complete prompts and had significant ly more time violations in comparison to their normative peers. The significant ly lower TMS and RVS found in the ASD sample also align s with Robinson, Goddard, Dritschel, Wis (2009) findings. However, r esults of the present study contradict those obtained by Happé et al. (2006), who found that those identified with ASD did not have planning deficits. Th is discrepancy may be due to the numerous adjustments made in the assessment administered by Happé et al. (2006), which include d: using a computerized version, not b minimum number of moves required to complete a prompt, encouragement to not start the prompt until a plan had been formulated, six practice trials, and adjustments in assessments given to hig h functioning participants. The se adaptations and the resulting additional information provided to participants during administration may have altered the planning approaches used by those identified with ASD , resulting in better performance .

PAGE 35

30 Results from this study indicate that individuals identified with ASD have significant deficit s in executive problem solving, planning, and impulse control compared to the general population. The significantly lower TMS indicates that the ASD sample used more moves than the normative sample to solve the same prompts on the TOL DX. This significance may be due to the two phenomena. When presented with a TOL DX formation, the examinee engages in one of two problem solving techniques known as exploratory behavior and final path behavior. On the TOL DX, when an examinee makes random moves that may bring them closer or further away from their intended goal, they are engaging in exploratory behavior. When an examinee recognizes the final sequence of steps that must be taken to achieve their goal, they are engaging in final path behavior (Kotovsky et al., 1985). The lower TMS demonstrates that those with ASD used more moves to complete the prompts ; therefore , they either spent more time in the exploratory behavior phase that resulted in additional random and ineffective moves, or they had ineffective final path behavior that required more moves than necessary to complete the prompt. Deficits in these phases and lower scores on the TMS are indicative of ineffective execut ive planning abilities, due to an examinee's limited capacity to utilize age appropriate reasoning abilities to implement strategic behavioral strategies to accomplish a goal (Levin et al 1991). Since planning has consistently be an executive functioning d omain found to be most impacted in those identified with ASD (Goldstein & Naglieri, 2013) , it came as no surprise that the ASD sample had significant more difficulty with this domain compared to the normative sample . The ability to plan is essential for de cision making activities, as well as being able to anticipate what may occur. Planning is an adaptive skills that is necessary in daily activities, such as dressing appropriately according to the weather and packing a lunch for later in the day. The ability to use previously obtained knowledge to change our behavior is important for adequat e self sufficiency

PAGE 36

31 and effective decision making skills. A s we anticipate future actions , it is necessary to comprehend constraints that may limit our actions, understand the consequences our actions may pose, and adapt to changes in our day. Impulse contr ol and inhibition are also known to be associated with an ASD identification ( Payina et al. , 2018). The significant difference in the RVS observed in the present study indicates that those with ASD experienced more difficulty inhibiting behavior that was p reviously outlined as against the rules. Pavina and colleagues hypothesized that such inhibitory deficits a re likely due to inattention rather than specified traits associated with ASD (Pavina et al., 2018). The findings of the present study provide suppor t for this as lower scores on measures of executive functioning were not associated with autism severity. Our executiv e functioning and planning abilities assist us in our daily lives through making appropriate adaptive behavioral choices through the use of working memory, problem solving, planning, self monitoring, self motivation, and interference control (Goldstein & N aglieri, 2013). Children with impacted executive functioning tend to be more isolated in unstructured play settings, and engage less with their peers (Freeman, Locke, Rotheram Fuller, & Mandell, 2017). In this study, those identified with ASD were found to have significant difficulty in the areas of executive problem solving, executive planning, and impulse control. These deficits may serve to exacerbate the social communication and soci al skills deficits inherent to ASD. Limitations While the results of this study serve to advance our knowledge of executive functioning in individuals with ASD , there are many limitations to this study that should be noted. First is the small sample size . This may have resulted in insufficient power to determine effects of autism

PAGE 37

32 severity. In addition, d ue to a lack of documentation, racial, cultural, and socio economic factors could not be considered in the analyses , which limits the generalizability o f this study to other groups. This study only examines an ASD identification according to scores on two standardized assessments (the ADOS 2 and TOL DX). Additional assessments may have contributed to further analysis of executive functioning abilities and traits associated with ASD. Fu ture research should examine differences across gender, racial, cultural, and socio economic factors. Additionally, as executive functioning abilities progress throughout an to developmental level and age would be extremely beneficial. Finally , the assessment of executive functioning was limited to functions measured by the TOL DX. More targeted assessments that focus on the time a participant spends in the exploratory behavi or cognitive process vs . the final path behavior cognitive process would be beneficial for understanding where more specified deficits exist. Conclusion ASD is a neurodevelopmental disorder that affects how an individual perceives and interacts with the world around them. Common traits associated with ASD include highly restricted and disruptive behaviors that violate common, unspoken rules of behavior by which the rest of society abides. E arly intervention is key to enhancing the quality of life with those identified with ASD ; consequently, accurate and early identification is critical in mediating the negative effects of the disorder. T his study aimed to examin e the executive functioning in children identified with ASD. Previous research has indicated that executive function deficits are implicated in autism, though no clearly identifiable profile in this regard has e merged. This may be due in part to met hodological differences in previous studies, including in how ASD was diagnosed and how executive functioning was assessed. The present study sought to overcome

PAGE 38

33 some of the limitations of previous research by including participants who were diagnosed with ASD by a qualified professional and the use of a standardized, performance based measure of executive functioning. ASD severity as indicated on the ADOS 2 Overall Total Score was not found to be a contributing factor in executive functioning and planning deficits as measured on the TOL DX. However, those identified with ASD were found to have significant deficits in executive problem solving, planning, and impulse control. Collectively, these findings suggest that children with ASD have such deficits regardless of degree of severity of the disorder. When planning for assessment and intervention, it is important to account for both the executive functioning a bilities of the individual, as well as the ASD symptom presentation. The highly restricted and disruptive behaviors, inhibited social communication, impacted facial expression interpretation, and restricted integration of emotions and dialogue are all pres ented at differing levels of severity according to the individual identified with ASD . Additionally, these associative traits co exist with impacted executive functioning, and need individualized and targeted early intervention. Addressing individual sympt oms, executive functioning , and planning deficits with assessment and intervention will result in a drastically improved quality of life for the individual.

PAGE 39

34 R EFERENCES Adams, N. C., & Jarrold , C. (2012). Inhibition in autism: Children with autism have difficulty inhibiting irrelevant distractors but not prepotent responses. Journal of A utism and D evelopmental D isorders, 42 (6), 1052 1063. American Psychiatric Association (2013). Diagnostic and statistics manual of mental disorders (5th ed.) Arlington, VA: American Psychiatric Publishing. t hat y s aying? Children with b etter e xecutive f unction ing p roduce and r epair c ommunication m ore e ffectively. Journal of Cognition and Development , 18 (4), 441 464 . Baio, J., Wiggins, L., Christensen, D . L., N. F. (2018). Prevalence of a utism s pectrum d isorder a mong c hildren a ged 8 y ears Autism and d evelopmental d isabilities Monitoring n etwork, 11 s ites, United States, 2014. MMWR Surveill ance Summ ary , 67 (SS 6) , 1 23. DOI: http://dx.doi.org/10.15585/mmwr.ss6706a1 Barahona Corrêa, J. B., & Filipe, C. N. (2016). A concise history of Asperger syndrome: the short reign of a troublesome diagnosis. Frontiers in P sychology, 6 , 2024. Barna, M. (2017). Autism s pectrum d isorder. Di scover, 38 (6), 62. Baron Cohen, S., Wheelwright, S., Scahill, V., Lawson, J., & Spong, A. (2001). Are intuitive physics and intuitive psychology independent? A test with children with Asperger Syndrome . Journal of Developmental and Learning Disorders, 5 , 4 7 78. Bennetto, L., Pennington, B. F., & Rogers, S. J. (1996). Intact and impaired memory functions in autism. Child D evelopment, 67 (4), 1816 1835. Berg, W. K., & Byrd, D. L. (2002). The Tower of London spatial problem solving task: Enhancing clinical and research implementation. Journal of Clinical and Experimental Neuropsychology, 24 (5), 586 604. Bernstein , J . H . , Waber , D . P . , & Oedssa , F . L. (1996). Developmental scoring system for the Rey Osterrieth Complex Figure . Lutz, FL.: Psychol ogical Assess ment Resources . Bianchi, L., & Macdonald, J. H. (1922). The mechanism of the brain and the function of the frontal lobes . Berkeley, CA: University of California Libraries Bishop, D. M. V. (1998). Development of the C C ommunication C hecklist (CCC): A method for assessing qualitative aspects of communicative impairment in children. Journal of Child Psychology and Psychiatry, 39 (6), 879 891

PAGE 40

35 Boyd, B. A., McBee, M., Hol tzclaw, T., Baranek, G. T., & Bodfish, J. W. (2009). Relationships among repetitive behaviors, sensory features, and executive functions in high functioning autism. Research in A utism S pectrum D isorders, 3 (4), 959 966. Brown , L . , Sherbenou , R . J . , & Johnsen , S . K. (1992). Test of N onverbal I ntelligence: A language free measure of cognitive ability. 3rd ed . Austin, TX: PRO ED. Chan , A . S. , (2006). Hong Kong List Learning Test. 2nd ed. Hong Kong: Department of Psychology and Clinical Psychology Centre, The Chinese University of Hong Kong. Chan, A. S., Cheung, M. C., Han, Y. M., Sze, S. L., Leung, W. W., Man, H. S., & To, C. Y. (2009). Executive function deficits and neural discordance in children with autism spectrum disorders. Clinical Neurophysiology, 120 (6), 1107 1115. Conners , C . K. (2000). . ON: Multi Health System. Constantino, J. N., & Gruber, C. P. (2012). Social R esponsiveness S cale (2nd ed.) . Los Angeles, CA: Western Psychological Services. Corbett, B. A., Constantine, L. J., Hendren, R., Rocke, D., & Ozonoff, S. (2009). Examining executive functioning in children with autism spectrum disorder, attention deficit hyperactivity disorder and typical development. Psychiatry R esearch, 166 (2), 210 222. Courchesne, E., Mouton, P. R., Calhoun, M. E., Semendeferi, K., Ahrens Barbeau, C., Hallet, M. J., ... & Pierce, K. (201 0 ). Neuron number and size in prefrontal cortex of children with autism. J AMA , 306 (18), 2001 2010 Courchesne, E., Redcay, E., & Ken nedy, D. P. (2004). The autistic brain: birth through adulthood. Current opinion in neurology, 17 (4), 489 496. Culbertson, W. C., & Zillmer, E. A. (1998). The Tower of LondonDX: A standardized approach to assessing executive functioning in children. Archiv es of Clinical Neuropsychology, 13 (3), 285 301. Culbertson, W. & Zillmer, E., (2005). The Tower of London Drexel University: 2nd Edition . North Tonawanda, NY: Multi Health Systems, Inc. Damasio, A. R., & Maurer, R. G. (1978). A neurological model for child hood autism. Archives of neurology, 35 (12), 777 786. Dawson, G. (2008). Early behavioral intervention, brain plasticity, and the prevention of autism spectrum disorder. Development and psychopathology, 20 (3), 775 803. De Beni , R . , Palladino , P. (2004). Decline in working memory updating through ageing: intrusion error analyses. Memory , 12 , 75 89. Delis, D. C., Kaplan, E., & Kramer, J. H. (2001). Delis Kaplan E xecutive F unction S ystem . San Antonio TX: Psychological Corporation)

PAGE 41

36 Diehl , J., Tang , K., Thomas , B. (2013) High f unctioning a utism (HFA). In: Volkmar F.R. (eds) Encyclopedia of Autism Spectrum Disorders . Springer, New York, NY Durand, V. M. (2014). Autism spectrum disorders: Background and cases. In V. M. Durand, Autism S spectrum D isorder: A C linical G uide for G eneral P ractitioners (pp. 9 15). Eapen, V. (2016). Early identification of autism spectrum disorder: Do we need a paradigm shift? Australian and New Zealand Journal of Psychiatry, 50 (8) 718 720 . Fisher, N., & Happé , F. (2005). A training study of theory of mind and executive function in children with autistic spectrum disorders. Journal of Autism and Developmental Disorders, 35 (6), 757 771. doi:10.1007/s10803 005 0022 9 Fletcher Watson, S., McConnell, F., Manola, E. , & McConachie, H. (2014). Interventions based on the theory of mind cognitive model for autism spectrum disorder (ASD). The Cochrane Database of Systematic Reviews, (3), CD008785. doi:10.1002/14651858.CD008785.pub2 Freeman, L. M., Locke, J., Rotheram Fuller, E., & Mandell, D. (2017). Brief Report: Examining Executive and Social Functioning in Elementary Aged Children with Autism. Journal of Autism and Developmental Disorders, 47 (6), 1890 1895. Friedman, N. P., & Miya ke, A. (2004). The relations among inhibition and interference control functions: A latent variable analysis. Journal of Experimental Psychology: General, 133 (1), 101 135. doi:10.1037/0096 3445.133.1.101 Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: a latent variable analysis. Journal of E xperimental P sychology: General, 133 (1), 101. Frith, U. (1989). Autism: Explaining the enigma . Blackwell Oxford Google Scholar. Frye, D., Zelazo, P. D., Brooks, P. J., & Samuels, M. C. (1996). Inference and action in early causal reasoning. Developmental Psychology, 32 (1), 120 131. Gearhart , S. (2018). Phineas Gage. Encyclopædia Britannica . Retrieved from https://academic eb com.aurarialibrary.idm.oclc.org/levels/collegiate/article/Phineas Gage/604924 Geurts, H. M., Corbett, B., & Solomon, M. (2009). The paradox of cognitive flexibility in autism. Trends in C ognitive S ciences, 13 (2), 74 82. Gioia, G. A., Isquith, P. K., Guy , S. C., & Kenworthy, L. (2000). Test review behavior rating inventory of executive function. Child Neuropsychology, 6 (3), 235 238. Goldstein, S., & Naglieri, J. A. (Eds.). (2013). Handbook of E F unctioning. Springer Science & Business Media.

PAGE 42

37 Gotham, K., P ickles, A., & Lord, C. (2009). Standardizing ADOS scores for a measure of severity in autism spectrum disorders. Journal of A utism and D evelopmental D isorders, 39 (5), 693 705. Gotham, K., Risi , S., Pickles, A., & Lord, C. (2007). The autism diagnostic observation schedule (ADOS): Revised algorithms for improved diagnostic validity. Journal of Autism and Developmental Disorders, 37 , 400 408. doi: 10.1007/s10803 006 0280 1. Hadjikhani, N. (2013). Frontal l obe f indings in a utism. In Encyclopedia of Autism Spectrum Disorders (pp. 1333 1339). Springer, New York, NY. Happé, F., Booth, R., Charlton, R., & Hughes, C. (2006). Executive function deficits in autism spectrum disorders and attention deficit/ hyperactivity disorder: examining profiles across domains and ages. Brain and C ognition, 61 (1), 25 39. Harlow, J. M. (1993). Recovery from the passage of an iron bar through the head. History of Psychiatry, 4 (14), 274 281. Hill, E. L. (2004). Evaluating th e theory of executive dysfunction in autism. Developmental Review, 24 (2), 189 233. doi:10.1016/j.dr.2004.01.001 Hill, E. L. (2004). Executive dysfunction in autism. Trends in Cognitive Sciences, 8 (1), 26 32. doi:10.1016/j.tics.2003.11.003 Hudson, J. A., Sh apiro, L. R., & Sosa, B. B. (1995). Planning in the real world: Preschool children's scripts and plans for familiar events. Child Development, 66 (4), 984 998. Hughes, C., Russell, J., & Robbins, T. W. (1994). Evidence for executive dysfunction in autism. N europsychologia, 32 (4), 477 492. Jolliffe, T., & Baron Cohen, S. (1999). A test of central coherence theory: Linguistic processing in high functioning adults with autism or A sperger syndrome: Is local coherence impaired? Cognition, 71 (2), 149 185. doi:10.1 016/S0010 0277(99)00022 0 communicative functioning in children with autism spectrum disorder. Journal of Child Psychology and Psychiatry, 43 (6), 807 821. Kim, Y. S., Leven thal, B. L., Koh, Y. J., Fombonne, E., Laska, E., Lim, E. C., ... & Song, D. H. (2011). Prevalence of autism spectrum disorders in a total population sample. American Journal of Psychiatry, 168 (9), 904 912. Kotovsky, K., Hayes, J.R., & Simon, H.A. (1985). Why are some problems hard? Evidence from the Tower of Hanoi. Cognitive Psychology, 17 , 248 294. Kouklari, E. C., Tsermentseli, S., & Auyeung, B. (2018). Executive function predicts theory of mind but not social verbal communication in school aged children with autism spectrum disorder. Research in D evelopmental D isabilities , 76, 12 24.

PAGE 43

38 Krikorian, R., Bartok, J., & Gay, N. (1994). Tower of London procedure: a standard method and developmental data. Journal of clinical and Experimental Neuropsychology, 16 (6), 840 850. Kroncke, A. P., Willard, M., & Huckabee, H. (2016). Assessment of a utism s pectrum d isorder: Critical i ssues in c linical, f orensic and s chool s ettings . New York, NY: Springer. Lemon, J. M., Gargaro, B., Enticott , P. G., & Rinehart, N. J. (2011). Brief report: Executive functioning in autism spectrum disorders: A gender comparison of response inhibition. Journal of A utism and D evelopmental D isorders, 41 (3), 352 356. Lord, C., Risi, S., Lambrecht, L., Cook Jr, E. H ., Leventhal, B. L., DiLavore, P. C., . . . Rutter, M. (2000). The autism diagnostic observation Schedule Generic: A standard measure of social and communication deficits associated with the spectrum of autism. Journal of Autism and Developmental Disorders , 30 (3), 205 223. doi:10.1023/A:1005592401947 Lord, C., Rutter, M. DiLavore, P. C., Risi, S., Gotham, K., & Bishop, S. (2012 ) . The Autism Diagnostic Observation Schedule Second Edition (ADOS 2 ). Torrance, CA: Western Psychological Services. Lord, C., Rutter, M., & Le Couteur, A. (1994). Autism Diagnostic Interview Revised: a revised version of a diagnostic interview for caregivers of individuals with possible pervasive developmental disorders. Journal of A utism and D evelopmental D isorders, 24 (5), 659 685. Luria, A. R., Karpov, B. A., & Yarbuss, A. L. (1966). Disturbances of active visual perception with lesions of the frontal lobes. Cortex, 2 (2), 202 212. Mangeot , S . , Armstrong K, Colvin A . N . , Yeates K . O . , & Taylor H . G. (2002). Long term executive function deficits in children with traumatic brain injuries: assessment using the behavior rating inventory of executive function (BRIEF). Child Neuropsychology , 8 , 271 84. Matson, J. L., & Kozlowski, A. M. (2011). The increasing preva lence of autism spectrum disorders. Research in Autism Spectrum Disorders, 5 (1), 418 425. Mayes, S. D., & Calhoun, S. L. (2003). Analysis of WISC III, Stanford Binet: IV, and academic achievement test scores in children with autism. Journal of A utism and D evelopmental D isorders, 33 (3), 329 341. Memari, A. H., Ziaee, V., Shayestehfar, M., Ghanouni, P., Mansournia, M. A., & Moshayedi, P. (2013). Cognitive flexibility impairments in children with autism spectrum disorders: links to age, gender and child outcom es. Research in Developmental Disabilities, 34 (10), 3218 3225. Merchan Naranjo, J., Boada, L., del Rey Mejías, Á., Mayoral, M., Llorente, C., Arango, C., & Parellada, M. (2016). Executive function is affected in autism spectrum disorder, but does

PAGE 44

39 not corre late with intelligence. Revista de Psiquiatría y Salud Mental (English Edition), 9 (1), 39 50. Monsell, S. (2003). Task switching. Trends in Cognitive Sciences, 7 (3), 134 140. doi:10.1016/S1364 6613(03)00028 7 Nouchine, H.,Volkmar , F. R., & SpringerLink (Online service). (2013) Executive f unctions. In: Volkmar F.R. , ( E ds . ) . Encyclopedia of Autism Spectrum Disorders . New York, NY : Springer . Ozonoff, S., & Jensen, J. (1999). Brief report: Specific executive function profiles in thre e neurodevelopmental disorders. Journal of A utism and D evelopmental D isorders, 29 (2), 171 177. Ozonoff, S., & McEvoy, R. E. (1994). A longitudinal study of executive function and theory of mind development in autism. Development and P sychopathology, 6 (3), 415 431. Ozonoff, S., Rogers, S. J., & Pennington, B. F. (1991). Asperger's syndrome: Evidence of an Journal of Child Psychology and Psychiatry, 32 (7), 1107 1122 ., & Martin, B. (2018). Autism, impulsivity and inhibition : A review of the literature. Basal Ganglia , 14 , 44 53 . Pellicano, E. (2010). Individual differences in executive function and central coherence predict developmental changes in theory of mind in autism . Developmental P sychology, 46 (2), 530. Perner, J., & Lang, B. (1999). Development of theory of mind and executive control. Trends in Cognitive Sciences, 3 (9), 337 344. Perner, J., & Lang, B. (2000). Theory of mind and executive function: Is there a developmental relationship? In D. J. Cohen, S. Baron Cohen, & H. Tager Flusberg (Eds.), Understanding other minds: Perspectives from developmental cognitive neuroscience (2nd ed., pp. 150 181). New York , NY : Oxford University Press. Pickering, S. J., & Gat hercole, S. E. (2001). Working M emory T est B attery for C hildren . London: Pearson Assessment. (2017). Behavioral and emotional problems in high functioning girls and boys with reports. Autism, 21 (6), 738 748. Robinson, S., Goddard, L., Dritschel, B., Wisley, M., & Howlin, P. (2009). Executive functions in children with autism spectrum disorders. Brain a nd C ognition, 71 (3), 362 368.

PAGE 45

40 Romine, C. B., & Reynolds, C. R. (2005). A model of the development of frontal lobe functioning: Findings from a meta analysis. Applied N europsychology, 12 (4), 190 201. Schopler, E., Reichler , R. J., & Renner, B. R. (1986). The Childhood Autism Rating Scale (CARS): For diagnostic screening and classification of autism . New York: Irvington. Shallice, T. (1982). Specific impairments of planning. Philosophical Transactions of the Royal Society of London. B, Biological Sciences , 298 (1089), 199 209. Shallice, T. (1988). From neuropsychology to mental structure . Cambridge University Press. Snodgrass, J. G., & Vanderwart , M. (1980). A standardized set of 260 pictures: norms for name agreement, image agreement, familiarity, and visual complexity. Journal of E xperimental P sychology: Human L earning and M emory, 6 (2), 174. Stockings of Cambridge (SOC). (n.d.). Retrieved from http://www.cambridgecognition.com/cantab/cognitive tests/executive function/stockings of cambridge soc/ Trammell, B., Wilczynski, S. M., Dale, B., & Mcintosh, D. E. (2013). Assessment and differential diagnosis of comorbid conditions in adol escents and adults with autism spectrum disorders. Psychology in the Schools, 50 (9), 936 946. Unterrainer, J. M., & Owen, A. M. (2006). Planning and problem solving: from neuropsychology to functional neuroimaging. Journal of Physiology Paris, 99 (4 6), 308 317. van den Bergh, S. F., Scheeren, A. M., Begeer, S., Koot, H. M., & Geurts, H. M. (2014). Age related differences of executive functioning problems in everyday life of children and adolescents in the autism spectrum. Journal of Autism and Developmental Disorders , 44 (8), 1959 1971. Van Eylen, L., Boets, B., Steyaert, J., Evers, K., Wagemans, J., & Noens, I. (2011). Cognitive flexibility in autism spectrum disorder: Explaining the inconsistencies? Research in Autism Spectrum Disorders, 5 (4), 1390 1401. Ve rte, S., Geurts, H. M., Roeyers, H., Oosterlaan, J., & Sergeant, J. A. (2006). Executive functioning in children with an autism spectrum disorder: Can we differentiate within the spectrum? Journal of A utism and D evelopmental D isorders, 36 (3), 351 372. Will iams, D. L., Mazefsky, C. A., Walker, J. D., Minshew, N. J., & Goldstein, G. (2014). Associations between conceptual reasoning, problem solving, and adaptive ability in high functioning autism. Journal of A utism and D evelopmental D isorders, 44 (11), 2908 29 20. Yuan, P., & Raz, N. (2014). Prefrontal cortex and executive functions in healthy adults: a meta analysis of structural neuroimaging studies. Neuroscience & Biobehavioral Reviews, 42 , 180 192.

PAGE 46

41 Zhang, J. (1997). The nature of external representations in problem solving. Cognitive Science, 21, 179 217.