Disembedding performance and recognition memory in autism/PDD

Perceptual decision-making in autism as assessed by “spot the difference” visual cognition tasks

Discriminating between similar figures proves to be a remarkably demanding task due to the limited capacity of our visual cognitive processes. Here we examine how perceptual inference and decision-making are modulated by differences arising from neurodiversity. A large sample of autistic (n = 140) and typical (n = 147) participants completed two forced choice similarity judgement tasks online. Each task consisted of “match” (identical figures) and “mismatch” (subtle differences between figures) conditions. Signal detection theory analyses indicated a response bias by the autism group during conditions of uncertainty. More specifically, autistic participants were more likely to choose the “mismatch” option, thus leading to more hits on the “mismatch” condition, but also more false alarms on the “match” condition. These results suggest differences in response strategies during perceptual decision-making in autism.

The Episodic Memory Profile in Autism Spectrum Disorder: A Bayesian Meta-Analysis

Although autism spectrum disorders (ASD) are commonly characterized by diminished episodic memory, the literature in this area is mixed. We address these inconsistent findings by employing multilevel Bayesian meta-analysis to quantify episodic memory differences between individuals with ASD and typically developing (TD) controls. We used meta-regression to evaluate the effects of test modality (e.g., word list, story recall), delay interval (immediate vs. delayed), retrieval demands (recognition vs. recall), and sensory modality (auditory vs. visual) on episodic memory in ASD. A total of 338 effect sizes from 113 empirical articles, including 5,632 unique participants (ASD = 2,777, TD = 2,855), were included. Results show that the memory deficits associated with ASD were larger for recall (g = -0.52, se = 0.04, 95% CrI [-0.60, -0.43]) compared to recognition (g = -0.25, se = 0.05, 95% CrI [-0.35, -0.14]) and differed based on the testing modality. For example, effect sizes were smallest for words (g = -0.28, se = 0.05, 95% CrI [-0.38, -0.18]), pictures (g = -0.38, se = 0.07, 95% CrI [-0.52, -0.24]), and figure reproduction (g = -0.49, se = 0.11, 95% CrI [-0.70, -0.27]). However, effect sizes for sentences (g = -0.59, se = 0.20, 95% CrI [-1.00, -0.21]), stories (Hedges' g = -0.54, se = 0.08, 95% CrI [-0.69, -0.38]) and staged events (g = -0.75, se = 0.10, 95% CrI [-0.95, -0.55]) were much larger. These findings suggest that ASD is associated with a small to medium reduction in scores on episodic memory tests relative to TD controls.

An investigation of visual narrative comprehension in children with autism spectrum disorders

The present study analyzed the comprehension of visual narrative in a group of twelve children with autism spectrum disorders (ASD). Their performances were compared to a control group of fifteen children with typical development (TD) matched for age, level of formal education, and IQ. Visual narrative comprehension was assessed by administering a task that required children to understand narrative's global coherence by arranging in the correct order the constituent parts of stories presented in pictures. Specifically, the task evaluated children's ability to grasp how single events connected (causally and temporally) each other and how these connections led to the ending of the story. Results showed that children with ASD obtained significantly lower scores than children with TD. These results open to alternative interpretations of narrative impairments often reported in individuals with ASD, which might not be restricted to the linguistic code but stem from a deeper deficit in narrative processing that is independent from the expressive modality.

Superior Disembedding in Children with ASD: New Tests Using Abstract, Meaningful, and 3D Contexts

Since its initial development, the embedded figures test (EFT) has been used extensively to measure local–global perceptual style. However, little is known about the perceptual factors that influence target detection. The current study aimed to investigate disembedding in children with and without ASD, aged 8–15 years, using the newly developed, stimulus-controlled L-EFT, M-EFT and D-EFT. Firstly, results revealed superior disembedding for children with ASD, irrespective of the type of target or embedding context, although the ASD group took more time in both the M-EFT and D-EFT. Secondly, the number of target lines continuing into the context proved more of a hindrance for the controls. Taken together, these findings provide strong evidence to support the notion of superior disembedding in ASD.

Perceptual Similarity in Autism

People with autism have consistently been found to outperform controls on visuo-spatial tasks such as block design, embedded figures, and visual search tasks. Plaisted, O'Riordan, and others (Bonnel et al., 2003; O'Riordan & Plaisted, 2001; O'Riordan, Plaisted, Driver, & Baron-Cohen, 2001; Plaisted, O'Riordan, & Baron-Cohen, 1998a, 1998b) have suggested that these findings might be explained in terms of reduced perceptual similarity in autism, and that reduced perceptual similarity could also account for the difficulties that people with autism have in making generalizations to novel situations. In this study, high-functioning adults with autism and ability-matched controls performed a low-level categorization task designed to examine perceptual similarity. Results were analysed using standard statistical techniques and modelled using a quantitative model of categorization. This analysis revealed that participants with autism required reliably longer to learn the category structure than did the control group but, contrary to the predictions of the reduced perceptual similarity hypothesis, no evidence was found of more accurate performance by the participants with autism during the generalization stage. Our results suggest that when all participants are attending to the same attributes of an object in the visual domain, people with autism will not display signs of enhanced perceptual similarity.

Proficiency of individuals with autism spectrum disorder at disembedding figures: A systematic review

OBJECTIVE

This systematic review examines the proficiency and visual search strategies of individuals with autism spectrum disorders (ASD) while disembedding figures and whether they differ from typical controls and other comparative samples.

METHODS

Five databases, including Proquest, Psychinfo, Medline, CINAHL and Science Direct were used to identify published studies meeting the inclusion and exclusion criteria.

RESULTS

Twenty articles were included in the review, the majority of which matched participants by mental age. Outcomes discussed were time taken to identify targets, the number correctly identified, and fixation frequency and duration.

CONCLUSIONS

Individuals with ASD perform at the same speed or faster than controls and other clinical samples. However, there appear to be no differences between individuals with ASD and controls for number of correctly identified targets. Only one study examined visual search strategies and suggests that individuals with ASD exhibit shorter first and final fixations to targets compared with controls.

Weak Central Coherence: A Cross-Domain Phenomenon Specific to Autism?

This study investigated whether evidence for the weak central coherence theory could be specifically associated with a group of children with autism compared with normally developing children ( n = 17 per group). Two tasks were employed, one involving visual illusions and the other verbal homophones. Both were based on tasks used in previous central coherence research. Incorporation of tasks involving the use of different domains (verbal versus visual) also enabled the investigation of claims that weak central coherence is a cross-domain processing style or deficit. The autistic group were found to be no different to the control group in performance on the visual illusions task. The autistic group made more errors than the normally developing group on the rare condition of the homophone task. However, analysis suggests this difference is mediated by verbal ability level and not diagnostic status per se. Theoretical implications and alternative explanations are discussed.

Can They See It? The Functional Field of View Is Narrower in Individuals with Autism Spectrum Disorder

Although social cognitive deficits have long been thought to underlie the characteristic and pervasive difficulties with social interaction observed in individuals with autism spectrum disorder (ASD), several recent behavioral and neuroimaging studies have indicated that visual perceptual impairments might also play a role. People with ASD show a robust bias towards detailed information at the expense of global information, although the mechanisms that underlie this phenomenon remain elusive. To address this issue, we investigated the functional field of view in a group of high-functioning children with autism (n = 13) and a paired non-ASD group (n = 13). Our results indicate that the ability to correctly detect and identify stimuli sharply decreases with greater eccentricity from the fovea in people with ASD. Accordingly, a probe analysis revealed that the functional field of view in the ASD group was only about 6.62° of retinal eccentricity, compared with 8.57° in typically developing children. Thus, children with ASD appear to have a narrower functional field of view. These results challenge the conventional hypothesis that the deficit in global processing in individuals with ASD is solely due to weak central coherence. Alternatively, our data suggest that a narrower functional field of view may also contribute to this bias.

Visuo-spatial performance in autism: a meta-analysis

Visuo-spatial skills are believed to be enhanced in autism spectrum disorders (ASDs). This meta-analysis tests the current state of evidence for Figure Disembedding, Block Design, Mental Rotation and Navon tasks in ASD and neurotypicals. Block Design (d = 0.32) and Figure Disembedding (d = 0.26) showed superior performance for ASD with large heterogeneity that is unaccounted for. No clear differences were found for Mental Rotation. ASD samples showed a stronger local processing preference for Navon tasks (d = 0.35); less clear evidence for performance differences of a similar magnitude emerged. We discuss the meta-analysis results together with other findings relating to visuo-spatial processing and three cognitive theories of ASD: Weak Central Coherence, Enhanced Perceptual Functioning and Extreme Male Brain theory.

A Point of Departure in the Comparison of Social and Nonsocial Visual Orienting Among Persons With Autism Spectrum Disorders

Endogenous visual orienting among children with autism spectrum disorders (ASDs) and among typically developing (TD) children was examined using a Posner-type task that was modified to include social and nonsocial cues and targets to test hypotheses regarding information (social or nonsocial) and cue processing (long or short stimulus onset asynchronies (SOAs)). The findings suggest intact endogenous orienting to face and mixed face targets using hand and arrow cues among children with ASDs who were matched to typically developing children (TDC) on the basis of nonverbal mental age (MA) at approximately 8.5 years. The findings from this study challenge the notions of a social orienting impairment and of mechanical social orienting as the children with ASDs in this study demonstrated strong orienting effects in all conditions and social sensitivity in the long stimulus onset asynchrony (SOA) condition.

Visuospatial processing in children with autism: no evidence for (training-resistant) abnormalities

Individuals with autism spectrum disorders (ASDs) have been assumed to show evidence of abnormal visuospatial processing, which has been attributed to a failure to integrate local features into coherent global Gestalts and/or to a bias towards local processing. As the available data are based on baseline performance only, which does not provide insight into cognitive/neural plasticity and actual cognitive potential, we investigated how training-resistant possible visuospatial processing differences between children with and without ASD are. In particular, we studied the effect of computerized versus face-to-face visuospatial training in a group of normally intelligent children with ASD and typically developing children as control. Findings show that (a) children with and without ASD do not differ much in visuospatial processing (as assessed by a tangram-like task) and the few differences we observed were all eliminated by training; (b) training can improve visuospatial processing (equally) in both children with ASD and normally developing children; and (c) computer-based and face-to-face training was equally effective.

Evidence for distinct cognitive profiles in autism spectrum disorders and specific language impairment

Findings that a subgroup of children with an autism spectrum disorder (ASD) have linguistic capabilities that resemble specific language impairment (SLI) have led some authors to hypothesise that ASD and SLI have a shared aetiology. While considerable research has explored overlap in the language phenotypes of the two conditions, little research has examined possible overlap in cognitive characteristics. In this study, we explored nonword and sentence repetition performance, as well as performance on the Children's Embedded Figures Test (CEFT) for children with ASD or SLI. As expected, 'language impaired' children with ASD (ALI) and children with SLI performed worse than both 'language normal' ASD (ALN) and typically developing (TD) children on the nonword and sentence repetition tests. Further, the SLI children performed worse than all other groups on the CEFT. This finding supports distinct cognitive profiles in ASD and SLI and may provide further evidence for distinct aetiological mechanisms in the two conditions.

Visual processing in adolescents with autism spectrum disorder: evidence from embedded figures and configural superiority tests

The embedded figures test has often been used to reveal weak central coherence in individuals with autism spectrum disorder (ASD). Here, we administered a more standardized automated version of the embedded figures test in combination with the configural superiority task, to investigate the effect of contextual modulation on local feature detection in 23 adolescents with ASD and 26 matched typically developing controls. On both tasks both groups performed largely similarly in terms of accuracy and reaction time, and both displayed the contextual modulation effect. This indicates that individuals with ASD are equally sensitive compared to typically developing individuals to the contextual effects of the task and that there is no evidence for a local processing bias in adolescents with ASD.

Relationships between visual figure discrimination, verbal abilities, and gender

This study investigated the relationships between verbal thinking and performance on visual figure discrimination tasks from a Vygotskian perspective in a large varied adult sample (N = 428). A test designed to assess the structure of word meanings (ie tendency to think in 'everyday' or 'scientific' concepts as distinguished by Vygotsky) together with two contour picture tasks was presented. Visual tasks were a modified version of Poppelreuter's overlapping figures and a picture depicting a meaningful scene. On both tasks concrete objects and abstract meaningless shapes had to be identified. In addition to relationships between visual task performance and word meaning structure, the effects of the meaningful scene and relations with gender were examined. The results confirmed the expected relation between word meaning structure and visual performance. Furthermore, they suggested a specific effect of the meaningful whole and a male advantage, especially for the first task in which women seemed to benefit less from advanced word meaning structure.

Re-examining the cognitive phenotype in autism: a study with young Chinese children

Deficits consistently found in autism include an impaired "theory of mind", weak central coherence, and deficits in executive function. The current study examined whether this traditional cluster of symptoms existed in a group of Chinese-speaking children with autism. Sixteen high-functioning, non-retarded children with autism were matched to 16 typically developing (TD) children on gender, non-verbal IQ and age. Non-verbal IQ's of all participants were measured using the Raven Progressive Matrices. Each participant was tested individually on measures of "theory of mind", central coherence and executive function. Results indicated that most, but not all, participants with autism performed significantly poorer on two standard measures of first-order "theory of mind," although there was no significant difference on two other measures of that domain. As expected, they performed significantly worse on executive function tasks. However, the hypothesis of weak central coherence in autism was not substantiated. There was no evidence that these three cognitive impairments co-existed in individuals with autism. More likely, each of these deficits appears singly or in pair instead of forming a cluster.

Is macrocephaly a neural marker of a local bias in autism?

Previous research has suggested that the local processing bias often reported in studies of Autism Spectrum Condition may only be typical of a subgroup of individuals with autism also presenting with macrocephaly. The current study examined a group of children with autism, with and without macrocephaly, on the Children's Embedded Figures Test (CEFT), a well-established measure of local processing bias. The results demonstrated that the children with autism and macrocephaly performed significantly better on the CEFT than children with autism without macrocephaly, indicative of a local bias. These results lend support to the proposal that both macrocephaly in autism and a local processing bias may arise from the same underlying neural processes and these characteristics represent an endophenotype in a subgroup of individuals with ASC worthy of further investigation.

Differences in global and local level information processing in autism: an fMRI investigation

People with autism spectrum disorders (ASD) have atypical visual perception of global and local information. Previous neuroimaging studies have examined the functional anatomy of locally directed attention during visual processing in ASD, but few have examined differences in both globally and locally directed attention. We performed functional magnetic resonance imaging (fMRI) in 17 adults with ASD and 16 typically developing (TD) subjects to examine the neurobiology of both global- and local-level information processing in ASD using an abstract hierarchical design task. TD subjects showed no regions of increased brain activation relative to subjects with ASD as assessed using whole brain analysis. Subjects with ASD exhibited greater activation in right superior frontal gyrus during locally directed attention. During globally directed attention, the ASD group showed greater right lateral occipital activation. Additionally, subjects with ASD showed less deactivation in medial prefrontal cortex (part of the default mode network) in the globally directed attention condition. Our findings help elucidate networks of brain activation related to atyipcal global and local feature processing in ASD.

Evidence for a cultural influence on field-independence in autism spectrum disorder

Field-independence, or weak central coherence, is a recognised phenotype of autism spectrum disorder (ASD). There is also evidence of cultural variation in this perceptual style, as neurotypical individuals from Western nations are more field-independent than neurotypical individuals from East-Asian nations. The majority of research on perceptual style in those with ASD has been carried out in Western nations therefore it is unclear whether increased field-independence in ASD is a culturally universal phenotype. Here, we assessed perceptual style in children with and without ASD from England and Singapore using the Children's Embedded Figures Test and the Framed-Line Test. We found increased field-independence in the English participants with ASD only, suggesting that weak central coherence in ASD is not culturally universal.

Performance of children with autism on the Embedded Figures Test: a closer look at a popular task

The Embedded Figures Test assesses weak central coherence and individuals with autism are commonly assumed to perform superiorly; however, the evidence for this claim is somewhat mixed. Here, two large (N = 45 and 62) samples of high-functioning children (6-16 years) with autism spectrum disorder performed similarly to typically-developing children on accuracy and reaction time measures; this could not be attributed to insufficient power. Inconsistent past findings are most likely due to methodological and analysis techniques, as well as heterogeneity in central coherence within autism spectrum disorders. While this task has been useful in establishing weak central coherence as a cognitive theory in autism, inconsistent past findings and its inability to disentangle global and local processing suggest that it should be used with caution in the future.

Functional evaluation of hidden figures object analysis in children with autistic disorder

Functional magnetic resonance imaging (fMRI) during performance of a hidden figures task (HFT) was used to compare differences in brain function in children diagnosed with autism disorder (AD) compared to children with attention-deficit/hyperactivity disorder (ADHD) and typical controls (TC). Overall greater functional MRI activity was observed in the two control groups compared to children with AD. Laterality differences were also evident, with AD subjects preferentially showing activity in the right medial temporal region while controls tended to activate the left medial temporal cortex. Reduced fMRI activity was observed in the parietal, ventral-temporal and hippocampal regions in the AD group, suggesting differences in the way that children with AD process the HFT.

Cortical underconnectivity coupled with preserved visuospatial cognition in autism: Evidence from an fMRI study of an embedded figures task

Individuals with high-functioning autism sometimes exhibit intact or superior performance on visuospatial tasks, in contrast to impaired functioning in other domains such as language comprehension, executive tasks, and social functions. The goal of the current study was to investigate the neural bases of preserved visuospatial processing in high-functioning autism from the perspective of the cortical underconnectivity theory. We used a combination of behavioral, functional magnetic resonance imaging, functional connectivity, and corpus callosum morphometric methodological tools. Thirteen participants with high-functioning autism and 13 controls (age-, IQ-, and gender-matched) were scanned while performing an Embedded Figures Task. Despite the ability of the autism group to attain behavioral performance comparable to the control group, the brain imaging results revealed several group differences consistent with the cortical underconnectivity account of autism. First, relative to controls, the autism group showed less activation in the left dorsolateral prefrontal and inferior parietal areas and more activation in visuospatial (bilateral superior parietal extending to inferior parietal and right occipital) areas. Second, the autism group demonstrated lower functional connectivity between higher-order working memory/executive areas and visuospatial regions (between frontal and parietal-occipital). Third, the size of the corpus callosum (an index of anatomical connectivity) was positively correlated with frontal-posterior (parietal and occipital) functional connectivity in the autism group. Thus, even in the visuospatial domain, where preserved performance among people with autism is observed, the neuroimaging signatures of cortical underconnectivity persist.

[Does the islet of ability on visuospatial tasks in children with high-functioning autism really indicate a deficit in global processing?]

OBJECTIVE

The literature on autism reports regularly the presence of a peak of ability on the visuospatial tasks. The classic interpretation of this result refers to the theoretical model proposed by Frith (1989) who evokes a "lack of central coherence" in persons with autism that is a deficit in the mobilization of global processing. The research reported here has for objective to propose a reflection on the relevance of this model by asking the following question: is global processing impaired in autism or simply not mobilized for the benefit of the almost exclusive appeal to local treatment?

METHODS

A group of children with high-functioning autism was compared with normally developping children (n=15 per group), matched on age and global level of intelligence. The clinical group, 14 boys and a girl, had received a diagnosis of typical autism according to the criteria of the ICD-10 (F84.0) confirmed by ADI-R. These children all used a functional language at the time of inclusion within the study, however all of them initially presented a delay in language (mean age: 8 years and 6 months; mean total IQ: 98.07). The typically developping group, 12 boys and three girls, were from ordinary school (mean age: 9 years, mean total IQ: 106.2). Two tasks were employed for the collection of data: the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) was used to estimate the total-, verbal- and performance-IQ scores of every child and to match both groups. It also permitted the evaluation and comparison of the performances of the children on the following visuospatial tasks: "picture completion", "object assembly" and "block design". The NEPSY scale permitted the estimation and comparison of the levels of performance of both groups on visuospatial functions.

RESULTS

In terms of scores, the tasks of the WISC-III, requiring visiospatial processing as well as the global evaluation of the visiospatial functions with the NEPSY, showed the absence of significant differences between children with high-functioning autism and typical children of the same age. However, differences of strategies appeared both between the groups and, in children with autism, according to the tasks to resolve. The comparison of subtests, "arrows" and "picture completion" on one hand, and "object assembly" and "block design" on the other, showed that children with autism are capable of mobilizing correct configural processing in the first ones but not in the second. The only factor which differentiates these tasks is the appeal or not to a motor coordination. It is possible that the lack of motor ease, often described in this type of children, sometimes leads them towards strategies of low level, i.e., to local adjustments, unlike the typical children who mobilize a strategy supported on a global representation of the purpose to be reached.

CONCLUSION

If our results confirm the capacities of children with autism to resolve the tasks requiring a visiospatial processing, the strategies which they mobilize do not support the existence of a weakness of the central coherence. We suggest, in persons with autism, the idea of a priority granted to the local information treatment in the absence of a deficit of global or configural processing.

Local vs. global approaches to reproducing the Rey Osterrieth Complex Figure by children, adolescents, and adults with high-functioning autism

Individuals with autism have an atypical pattern of visual processing. Various studies have provided evidence that individuals with autism perceive the details of stimuli before the gestalt, the reverse of the typical pattern of visual processing. This study used the Rey Osterreith Complex Figure (ROCF) task and an objective scoring system to examine local/global processing approaches to its reproduction in 37 individuals diagnosed with high-functioning autism (HFA) compared to 49 age-, IQ-, and gender-matched typically developing controls (TD). The sample was divided into children (aged 8-14 years) and adolescents/adults (aged 15-47 years) to assess age effects. Results showed no difference in overall performance on the ROCF between HFA and TD children. TD participants displayed improved organizational and planning skills with age and a shift to global processing approaches, but there were no differences in performance between children and adolescents/adults with HFA. There was no evidence of enhanced local processing in either HFA group. These findings suggest that HFA individuals with average IQ scores do not have the clinically demonstrable evidence of the enhanced local processing thought to reflect increased local brain connectivity in more severely autistic individuals. The deficient global processing of the HFA adults reflects dependence of performance on impaired strategic problem-solving abilities, which has been demonstrated to result from under development of neural connectivity between visuo-spatial and frontal brain regions in HFA adults.

A new step towards understanding Embedded Figures Test performance in the autism spectrum: the radial frequency search task

The Embedded Figure Test (EFT) requires locating a simple shape embedded within a background of overlapping target-irrelevant scene elements. Observers with autism, or those with high levels of autistic-like traits, typically outperform matched comparison groups on the EFT. This research investigated the critical visual properties which give rise to this improved performance. The EFT is a search task and so here a radial frequency (RF) search task was created to directly explore efficacy of visual search and also the influence of element overlap on performance. In all conditions, the task was to detect whether the target RF3 (a triangular shape chosen for its visual properties) was present among a number of distracter RF4 (a square shape) patterns. The conditions employed were: 'singles', where all the patterns were spatially discrete, 'pairs', where two overlapping elements formed each cluster, and 'quads', comprising four overlapping elements per cluster. Compared to students scoring low on the Autism Spectrum Quotient (AQ; n=27), those scoring high on the AQ (n=23) were faster on the EFT and also significantly less influenced by increasing set size of the stimulus array in all RF search task conditions. However, the group difference in RF search performance was unaffected by the amount of stimulus overlap. Thus a simple search task is sufficient to detect a performance advantage associated with higher levels of autistic traits and has the advantages of a solid footing in visual theory and being readily repeatable for the purpose of assessing performance variability and change with interventions.

Vision in autism spectrum disorders

Autism spectrum disorders (ASDs) are developmental disorders which are thought primarily to affect social functioning. However, there is now a growing body of evidence that unusual sensory processing is at least a concomitant and possibly the cause of many of the behavioural signs and symptoms of ASD. A comprehensive and critical review of the phenomenological, empirical, neuroscientific and theoretical literature pertaining to visual processing in ASD is presented, along with a brief justification of a new theory which may help to explain some of the data, and link it with other current hypotheses about the genetic and neural aetiologies of this enigmatic condition.

Perceiving the impossible

Mottron and colleagues found that individuals with autism were less affected by geometric impossibility than comparison participants on a copying task. The current experiment sought to determine whether a local perceptual style could account for this. Participants with and without autism copied possible and impossible geometric figures. Geometric impossibility had a larger effect on drawing time for comparison participants than for those with autism. However, participants with autism did not use more localized drawing strategies. Strength of impossibility effect was associated with a global strategy amongst comparison participants but this relationship was not found amongst participants with autism. The findings suggest that differences in high-level conceptual processing may account for group differences in effects of impossibility.

Big heads, small details and autism

Autism is thought to be associated with a bias towards detail-focussed processing. While the cognitive basis remains controversial, one strong hypothesis is that there are high processing costs associated with changing from local into global processing. A possible neural mechanism underlying this processing style is abnormal neural connectivity; specifically reduced structural or functional connectivity between brain regions might lead to good exemplar-based processing but poor generalisation. Abnormal neural connectivity has also been suggested to account for the increased incidence of macrocephaly in autism (increased head/brain size). The present study therefore investigated the effect of head size on the ability to switch between global and local processing in autism. 49 high-functioning 7-12 year olds with autism (12 with macrocephaly) were compared to 25 normally developing children in their performance on a Local-Global Switching task. Those children with autism who also had macrocephaly showed a greater processing cost when switching into global processing, or 'zooming out', than both the remaining children with autism and the control children. A second experiment revealed that macrocephaly in the context of normal development is not associated with difficulty switching into global processing but rather occurs in children who are physically large. Macrocephaly in the context of autism may therefore be a biological marker of abnormal neural connectivity, and of a local processing bias.

Brief report: visuospatial analysis and self-rated autistic-like traits

Although there is good evidence that the behavioral traits of autism extend in lesser form to the general population, there has been limited investigation of whether cognitive features of the disorder also accompany these milder traits. This study investigated whether the superiority in visuospatial analysis established for individuals with autism also extends to individuals in the general population who self-report autistic-like traits. In an initial study, students scoring high on the Autism-spectrum Quotient (AQ) were faster and more accurate on the Embedded Figures Test (EFT) and the Block Design subscale of the Wechsler Intelligence Scale III compared to those scoring low on the AQ. A second study showed that high AQ scorers were faster to complete the EFT compared to low AQ scorers irrespective of IQ. Results are discussed with reference to weak central coherence theory and the autism spectrum.

Atypical neural substrates of Embedded Figures Task performance in children with Autism Spectrum Disorder

Superior performance on the Embedded Figures Task (EFT) has been attributed to weak central coherence in perceptual processing in Autism Spectrum Disorder (ASD). The present study used functional magnetic resonance imaging to examine the neural basis of EFT performance in 7- to 12-year-old ASD children and age- and IQ-matched controls. ASD children activated only a subset of the distributed network of regions activated in controls. In frontal cortex, control children activated left dorsolateral, medial and dorsal premotor regions whereas ASD children only activated the dorsal premotor region. In parietal and occipital cortices, activation was bilateral in control children but unilateral (left superior parietal and right occipital) in ASD children. Further, extensive bilateral ventral temporal activation was observed in control, but not ASD children. ASD children performed the EFT at the same level as controls but with reduced cortical involvement, suggesting that disembedded visual processing is accomplished parsimoniously by ASD relative to typically developing brains.

A New Computerised Advanced Theory of Mind Measure for Children with Asperger Syndrome: The ATOMIC

This study examined the ability of children with Asperger Syndrome (AS) to attribute mental states to characters in a new computerised, advanced theory of mind measure: The Animated Theory of Mind Inventory for Children (ATOMIC). Results showed that children with AS matched on IQ, verbal comprehension, age and gender performed equivalently on central coherence questions, but more poorly on the theory of mind questions compared with controls. A significant relationship was found between performance on ATOMIC and accuracy of mental state explanations provided on (Happé's, Journal of Autism and Developmental Disorders, 24, 129-154, 1994) Strange Stories Task, supporting the validity of the new measure. Limitations of the study and suggestions for future research are discussed.

Disembedding performance in children and adolescents with Asperger syndrome or high-functioning autism

The aim of the present study was to assess the findings, reported in earlier studies, that individuals with autism spectrum disorders process visuo-spatial tasks faster than typically developing control persons. The participants in the present study were children and adolescents with Asperger syndrome (AS) or high-functioning autism (HFA) (N = 13), and a matched group of typically developing children and adolescents (N = 13). The results showed that the participants in the clinical group performed marginally less well than those in the control group on both the Block Design Test and the Embedded Figures Test, but the differences were not statistically significant. Thus, earlier findings suggesting that individuals with autism spectrum disorders solve non-social cognitive tasks faster than typically developing control persons were not replicated. The results are discussed with special reference to the hypothesis of weak central coherence.

Priming the meaning of homographs in typically developing children and children with autism

Two explanations for deficits underlying autism were tested: weak central coherence (WCC) and executive dysfunction. Consistent with WCC, Happé (British Journal of Developmental Psychology 15 (1997) 1) found that children with autism failed to use sentence context in pronouncing homographs. In an alternate approach, we investigated whether children with autism can use meanings of related word primes. We presented children with autism and controls with primes for homographs, semantically related, and unrelated targets. Children with autism used primes to correctly pronounce homographs upon first presentation but showed difficulty inhibiting prior responses upon later presentation of the homographs with different primes. Children with autism also showed semantic priming effects. We conclude that children with autism do not show an absolute deficit in ability to use contextual information.

Sorting preference in children with autism: the dominance of concrete features

The current study investigates preference to sort objects on the basis of either concrete or abstract features in children with and without autism. Participants were asked to sort a set of books into two groups that could be differentiated according to concrete (color, size) or abstract criteria (category membership: sports/games). The results showed that those with autism, unlike controls, were significantly more likely to sort according to a concrete criterion. In a further phase of testing, those with autism still did not sort according to abstract criteria, even when this was the only basis for sorting systematically. The findings are interpreted as evidence for a preference in autism to process concrete over abstract features of stimuli.

Neurophysiological correlates of relatively enhanced local visual search in autistic adolescents

Previous studies found normal or even superior performance of autistic patients on visuospatial tasks requiring local search, like the Embedded Figures Task (EFT). A well-known interpretation of this is "weak central coherence", i.e. autistic patients may show a reduced general ability to process information in its context and may therefore have a tendency to favour local over global aspects of information processing. An alternative view is that the local processing advantage in the EFT may result from a relative amplification of early perceptual processes which boosts processing of local stimulus properties but does not affect processing of global context. This study used functional magnetic resonance imaging (fMRI) in 12 autistic adolescents (9 Asperger and 3 high-functioning autistic patients) and 12 matched controls to help distinguish, on neurophysiological grounds, between these two accounts of EFT performance in autistic patients. Behaviourally, we found autistic individuals to be unimpaired during the EFT while they were significantly worse at performing a closely matched control task with minimal local search requirements. The fMRI results showed that activations specific for the local search aspects of the EFT were left-lateralised in parietal and premotor areas for the control group (as previously demonstrated for adults), whereas for the patients these activations were found in right primary visual cortex and bilateral extrastriate areas. These results suggest that enhanced local processing in early visual areas, as opposed to impaired processing of global context, is characteristic for performance of the EFT by autistic patients.

Superior disembedding performance of high-functioning individuals with autism spectrum disorders and their parents: the need for subtle measures

We assessed the disembedding performance on the Embedded Figures Test (EFT) of high-functioning subjects with autism or autism spectrum disorders from multi-incidence families and the performance of their parents. The individuals with autism spectrum disorders were significantly faster than matched controls in locating the shape, but their parents were not faster than a control group of parents. However, both the individuals with autism spectrum disorders and their fathers made significantly fewer incorrect attempts before finding the right shape than matched controls. These results suggest that the number of incorrect attempts is a more subtle measure than accuracy or response time for assessing superior disembedding skills and therefore may be useful in the assessment of individuals with autism spectrum disorders.

The Impact of Meaning and Dimensionality on Copying Accuracy in Individuals with Autism

Weak Central Coherence (Frith, 1989) predicts that, in autism, perceptual processing is relatively unaffected by conceptual analysis. Enhanced Perceptual Functioning (Mottron & Burack, 2001) predicts that the perceptual processing of those with autism is less influenced by conceptual analysis only when higher-level processing is detrimental to task performance. This research tested these theories using a copying task where one conceptual aspect enhances accuracy (meaningfulness) and another hinders it (three-dimensionality). Children and adolescents with and without autism copied meaningful and non-meaningful two-dimensional and three-dimensional line drawings. Drawing accuracy and strategy (global/local) were assessed. Participants with autism were less affected by dimensionality but not meaningfulness, apparently supporting EPF. Effects of dimensionality did not relate to drawing strategy, also contrary to WCC.

Gestalt perception and local-global processing in high-functioning autism

This study examined gestalt perception in high-functioning autism (HFA) and its relation to tasks indicative of local visual processing. Data on of gestalt perception, visual illusions (VI), hierarchical letters (HL), Block Design (BD) and the Embedded Figures Test (EFT) were collected in adult males with HFA, schizophrenia, depression and normative controls. Individuals with HFA processed gestalt stimuli less in accord with gestalt laws, particularly regarding the principle of similarity. Gestalt processing correlated positively with global processing of the HL. EFT and BD performance correlated negatively with VI susceptibility in HFA. All clinical groups succumbed less to VI than the normative sample. Results suggest decreased gestalt perception in HFA, being associated with a more general local visual processing bias.

The weak coherence account: detail-focused cognitive style in autism spectrum disorders

"Weak central coherence" refers to the detail-focused processing style proposed to characterise autism spectrum disorders (ASD). The original suggestion of a core deficit in central processing resulting in failure to extract global form/meaning, has been challenged in three ways. First, it may represent an outcome of superiority in local processing. Second, it may be a processing bias, rather than deficit. Third, weak coherence may occur alongside, rather than explain, deficits in social cognition. A review of over 50 empirical studies of coherence suggests robust findings of local bias in ASD, with mixed findings regarding weak global processing. Local bias appears not to be a mere side-effect of executive dysfunction, and may be independent of theory of mind deficits. Possible computational and neural models are discussed.

Patterns of Nonverbal Cognitive Functioning in Young Children with Autism Spectrum Disorders

Previous research demonstrates an uneven pattern of cognitive abilities in children with autism spectrum disorders (ASDs). This study examined whether this uneven pattern exists within the nonverbal domain in young children. We hypothesized relative strengths in perceptual abilities and weaknesses in nonverbal conceptual abilities in preschoolers with ASDs compared to groups with non-autism developmental delays and typical development. Profiles were examined using the Leiter International Performance Scale-Revised. The ASD group displayed clear relative strengths in visuospatial disembedding and detail-focused processing, with relative weaknesses in abstraction and concept formation. This contrasted with patterns of roughly equivalent abilities in both comparison groups. These findings have implications for subsequent development and may represent key features of the cognitive profile of autism.

Fragmented Visuospatial Processing in Children with Pervasive Developmental Disorder

Children diagnosed with Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) and Asperger Syndrome (AS) may be characterised by a similar perceptual focus on details as children with autistic disorder (AD). This was tested by analysing their performance in a visuoperceptual task [the Children's Embedded Figure Test (CEFT)] and a graphic reproduction task [the Rey Complex Figure Task (Rey CFT)]. Control groups were children with Tourette Syndrome (TS) and typically developing children. The TS sample performed similarly to the normal control group in both tasks. The CEFT results did not show the expected preference for local processing in children with PDD-NOS. However, the Rey CFT data revealed that the children with this lesser variant of PDD processed visuospatial information in a fragmented way and were deficient in global processing.

Spatial cognition in autism spectrum disorders: superior, impaired, or just intact?

The profile of spatial ability is of interest across autism spectrum disorders (ASD) because of reported spatial strengths in ASD and due to the recent association of Asperger's syndrome with Nonverbal Learning Disability. Spatial functions were examined in relation to two cognitive theories in autism: the central coherence and executive function (EF) theories. Performance on spatial tasks, EFs, and global/local processing was compared in children with ASD and controls. While the ASD group had faster reaction times on the Embedded Figures task, spatial performance was intact, but not superior, on other tasks. There was no evidence for impairments in EF or in processing global/local information, therefore contradicting these two theories. The implications of these results for these two theories are discussed.

A comparison of central coherence skills between adolescents with an intellectual disability with and without comorbid autism spectrum disorder

Central coherence theory hypothesizes individuals with autism process information in a detail-focused fashion. The present study examined whether adolescents with an intellectual disability and comorbid autism spectrum disorder showed a weaker central coherence than age- and IQ-matched controls. The central coherence skills of 43 adolescents from schools for students with severe learning problems were examined with two cognitive tasks. In these two tasks, detail-focused processing is beneficial to global processing to perform the tasks accurately and quickly. The group with autism spectrum disorder performed better than the control group. Adolescents with an intellectual disability and with comorbid autism spectrum disorder have a weaker central coherence than age- and IQ-matched controls. Partial support was also given for variability in weak central coherence within the autism spectrum.

Multiple cognitive capabilities/deficits in children with an autism spectrum disorder: “Weak” central coherence and its relationship to theory of mind and executive control

This study examined the validity of "weak" central coherence (CC) in the context of multiple cognitive capabilities/deficits in autism. Children with an autism spectrum disorder (ASD) and matched typically developing children were administered tasks tapping visuospatial coherence, false-belief understanding and aspects of executive control. Significant group differences were found in all three cognitive domains. Evidence of local processing on coherence tasks was widespread in the ASD group, but difficulties in attributing false beliefs and in components of executive functioning were present in fewer of the children with ASD. This cognitive profile was generally similar for younger and older children with ASD. Furthermore, weak CC was unrelated to false-belief understanding, but aspects of coherence (related to integration) were associated with aspects of executive control. Few associations were found between cognitive variables and indices of autistic symptomatology. Implications for CC theory are discussed.