There has been considerable recent interest in the cognitive style of individuals with Autism Spectrum Disorder (ASD). One theory, that of weak central coherence, concerns an inability to combine stimulus details into a coherent whole. Here we test this theory in the case of sound patterns, using a new definition of the details (local structure) and the coherent whole (global structure). Thirteen individuals with a diagnosis of autism or Asperger's syndrome and 15 control participants were administered auditory tests, where they were required to match local pitch direction changes between two auditory sequences. When the other local features of the sequence pairs were altered (the actual pitches and relative time points of pitch direction change), the control participants obtained lower scores compared with when these details were left unchanged. This can be attributed to interference from the global structure, defined as the combination of the local auditory details. In contrast, the participants with ASD did not obtain lower scores in the presence of such mismatches. This was attributed to the absence of interference from an auditory coherent whole. The results are consistent with the presence of abnormal interactions between local and global auditory perception in ASD.

Previous work suggests children with autism show superior performance (in relation to their general mental age) on the Embedded Figures Test (EFT). Frith interprets this as showing that they have "weak central coherence". In Experiment 1, using an adult level version of this task, we aimed to replicate and extend this finding, first, by collecting response time (RT) data; second, by testing adults with autism of normal intelligence; and third, by testing a group of adults with Asperger syndrome, in order to test for differences between autism and Asperger syndrome. Both clinical groups were significantly faster on the EFT. In Experiment 2, we investigated if this difference was due to a preference for local over global processing, using a novel drawing task based on the classical Rey Figure. The clinical groups did not differ significantly on this test, but there was a trend towards such a difference. Alternative explanations for the EFT superiority in autism and Asperger syndrome are considered.

Autism spectrum conditions are neuro-developmental syndromes with strong heritability. Cognitive theories have had some success in explaining why the cluster of features should co-occur. Empathizing deficits have the potential to make sense of one triad of impairments (social difficulties, communication difficulties and imagining others' minds), and may have a brain basis in the amygdala and left medial frontal cortex. A strong systemizing drive may account for a distinct triad of strengths (good attention to detail, deep, narrow interests and islets of ability). The brain basis of systemizing is yet to be understood. Family genetics studies suggest that these same cognitive dimensions (reduced empathizing alongside a strong drive to systemize) may also characterize the 'broader phenotype' among first-degree relatives. Molecular genetic studies are underway and any candidate genes for autism will ultimately need to be tested in relation to the observed differences in the brain, cognition and behaviour. The ethics of genetic screening or gene therapy should be thought about well ahead of these becoming available, since there is by no means any consensus that these would be desirable given the wide range of phenotypic traits, not all of which are disabling. Future research will need to focus on evaluating the extent to which any form of intervention reduces the triad of impairments whilst supporting the triad of strengths.

This article will argue that we can discover more about developmental disorders such as autism through demonstrations of task success than through examples of task failure. Even in exploring and explaining what people with autism find hard, such as social interaction, demonstration of competence on contrasting tasks has been crucial to defining the nature of the specific deficit. Current deficit accounts of autism cannot explain, however, the assets seen in this disorder; for example, savant skills in maths, music, drawing, islets of ability in visuo-spatial tests and rote-memory. An alternative account is reviewed here that suggests that autism is characterised by a cognitive style biased toward local versus global information processing; 'weak central coherence'. A tendency for featural processing in autism, often leading to superior performance, has been demonstrated at several levels. Normal individual differences may span a continuum of cognitive style from weak to strong coherence, with both assets and deficits associated with each extreme.

Evidence is presented which indicate that these children spontaneously display only a fraction of their knowledge, disguising their real cognitive capacity by their autistic pattern of behaviour... No academic researcher can command the required knowledge of the individually specific autistic child to be able to extract the knowledge that the child does not voluntary reveal. Only full time workers with the child or someone who is prepared to invest months in close interaction with specific autistic children, can hope, with the utilization of intrusive techniques, to obtain anything like true assessments and measurements of their real knowledge and abilities, hidden behind their general and specific blocking behaviour. This is the reason that some parents and a few teachers have been successful with a few children, but interaction and success with all autistic children is possible, and their autistic pattern of behaviour can be overcome to a certain extent. Parents and teachers of autistic children should maintain hope, enthusiasm and high level of expectation.

Estimates for the prevalence of mental retardation in autistic children and adults range from 25 to 70 percent or more, and when autistics do exhibit phenomenal skills (like Rain Man), researchers don't consider that "true" intelligence. Health workers routinely assess autistics using a standard IQ test known as the Wechsler test. But this test requires that children understand oral commands, a trait that many autistic children have trouble with. Cognitive neuroscientist Laurent Mottron of the Hôpital Rivière-des-Prairies, Montreal and colleagues noticed that autistic children did poorly on the verbal comprehension part of the Wechsler but exceedingly well on a part that tests non-verbal intelligence and reasoning.

When considering the cognitive abilities of people with autism, the majority of studies have explored domains in which there are deficits. However, on tests of local processing and visual search, exemplified by the Embedded Figures Task (EFT), people with autism have been reported to demonstrate superiority over normal controls. This study employed functional MRI of subjects during the performance of the EFT to test the hypothesis that normal subjects and a group with autism would activate different brain regions and that differences in the patterns of these regional activations would support distinct models of cerebral processing underlying EFT performance in the two groups. It was found that several cerebral regions were similarly activated in the two groups. However, normal controls, as well as demonstrating generally more extensive task-related activations, additionally activated prefrontal cortical areas that were not recruited in the group with autism. Conversely, subjects with autism demonstrated greater activation of ventral occipitotemporal regions. These differences in functional anatomy suggest that the cognitive strategies adopted by the two groups are different: the normal strategy invokes a greater contribution from working memory systems while the autistic group strategy depends to an abnormally large extent on visual systems for object feature analysis. This interpretation is discussed in relation to a model of autism which proposes a predisposition towards local rather than global modes of information processing.

Children with a diagnosis of autism and typically developing children were given two variations of the Navon task (Navon, 1977), which required responding to a target that could appear at the global level, the local level, or both levels. In one variation, the divided attention task, no information was given to children regarding the level at which a target would appear on any one trial. In the other, the selective attention task, children were instructed to attend to either the local or the global level. Typically developing children made most errors when the target appeared at the local level whereas children with autism made more errors when the target appeared at the global level in the divided attention task. Both groups of children were quicker to respond to the global target than the local target in the selective attention task. The presence of normal global processing in the children with autism in one task but not in the other is discussed in terms of a deficit in mechanisms that inhibit local information in the absence of overt priming or voluntary selective attention to local information.

The authors propose that an individual's superior ability to detect, match, and reproduce simple visual elements allows them to perform better in tasks relying on detection and graphic reproduction of visual elements that are included in a map. Individuals with autism appear to discriminate, detect, and memorize simple visual patterns better than typical individuals, which may account for their superior performance in visual-spatial tasks that rely on recognizing and memorizing landmarks or detecting similarities between a map and landmark features. Thus, in non-social settings, children with HFA and Asperger syndrome have superior spatial abilities than typically developing individuals, which has been seen in other similar studies of visual-spatial tests in these individuals.

Visuo-perceptual processing in autism is characterized by intact or enhanced performance on static spatial tasks and inferior performance on dynamic tasks, suggesting a deficit of dorsal visual stream processing in autism. However, previous findings by Bertone et al. indicate that neuro-integrative mechanisms used to detect complex motion, rather than motion perception per se, may be impaired in autism. We present here the first demonstration of concurrent enhanced and decreased performance in autism on the same visuo-spatial static task, wherein the only factor dichotomizing performance was the neural complexity required to discriminate grating orientation. The ability of persons with autism was found to be superior for identifying the orientation of simple, luminance-defined (or first-order) gratings but inferior for complex, texture-defined (or second-order) gratings. Using a flicker contrast sensitivity task, we demonstrated that this finding is probably not due to abnormal information processing at a sub-cortical level (magnocellular and parvocellular functioning). Together, these findings are interpreted as a clear indication of altered low-level perceptual information processing in autism, and confirm that the deficits and assets observed in autistic visual perception are contingent on the complexity of the neural network required to process a given type of visual stimulus. We suggest that atypical neural connectivity, resulting in enhanced lateral inhibition, may account for both enhanced and decreased low-level information processing in autism.

Children with autism are superior to typically developing children at visual search tasks. This study investigates the reasons for this phenomenon. The performance of children with autism and of typically developing children was compared on a series of visual search tasks to investigate two related problems. The first issue was whether the critical determinant of search rate in children is the discriminability of the display items, as it is in normal adults. The second question investigated was whether the superior performance of individuals with autism on visual search tasks is due to an enhanced ability to discriminate between display items. The results demonstrated that discriminability is the rate-determining factor for children with and without autism, replicating earlier findings with normal adults, and that children with autism have an enhanced ability to discriminate between display items. Thus, it seems that an enhanced ability to discriminate between display items underlies superior visual search in autism.

High-functioning adults with autism and control adults were tested on a perceptual learning task that compared discrimination performance on familiar and novel stimuli. Control adults were better able to discriminate familiar than novel stimuli--the perceptual learning effect. No perceptual learning effect was observed in adults with autism although they discriminated the novel stimuli significantly better than control adults. This enhanced discrimination learning about novel, but not familiar, stimuli in autism is discussed in relation to two current hypotheses of information processing in autism--weak central coherence and reduced attention-switching--and a new third hypothesis, which suggests that features held in common between stimuli are processed poorly and features unique to a stimulus are processed well in autism.

We propose an �Enhanced Perceptual Functioning� model encompassing the main differences between autistic and non-autistic social and non-social perceptual processing: locally oriented visual and auditory perception, enhanced low-level discrimination, use of a more posterior network in �complex� visual tasks, enhanced perception of first order static stimuli, diminished perception of complex movement, autonomy of low-level information processing toward higher-order operations, and differential relation between perception and general intelligence. Increased perceptual expertise may be implicated in the choice of special ability in savant autistics, and in the variability of apparent presentations within PDD (autism with and without typical speech, Asperger syndrome) in non-savant autistics. The overfunctioning of brain regions typically involved in primary perceptual functions may explain the autistic perceptual endophenotype.

Past research has shown a superiority of participants with high-functioning autism over comparison groups in memorizing picture-pitch associations and in detecting pitch changes in melodies. A subset of individuals with autism, known as "musical savants," is also known to possess absolute pitch. This superiority might be due to an abnormally high sensitivity to fine-grained pitch differences in sounds. To test this hypothesis, psychoacoustic tasks were devised so as to use a signal detection methodology. Participants were all musically untrained and were divided into a group of 12 high-functioning individuals with autism and a group of 12 normally developing individuals. Their task was to judge the pitch of pure tones in a "same-different" discrimination task and in a "high-low" categorization task. In both tasks, the obtained psychometric functions revealed higher pitch sensitivity for subjects with autism, with a more pronounced advantage over control participants in the categorization task. These findings confirm that pitch processing is enhanced in "high-functioning" autism. Superior performance in pitch discrimination and categorization extends previous findings of enhanced visual performance to the auditory domain. Thus, and as predicted by the enhanced perceptual functioning model for peaks of ability in autism (Mottron & Burack, 2001), autistic individuals outperform typically developing population in a variety of low-level perceptual tasks.

Autism is a developmental disorder characterized by deficits in social cognition, delays in language learning, and idiosyncratic interests and repetitive behaviours. Individuals with autism show superior performance in identifying shapes within the designs of the Embedded Figures Test. People with autism also perform better than controls on the Block Design test. To explain these findings consider the Weak Central Coherence Hypothesis which suggests that autistic individuals focus on local (rather than global) aspects of a scene. This focus on local details, instead of attention to the whole or global meaning of the picture, would lead to superior performance on these tasks.

Our results indicate that, with respect to accuracy, subjects with autism did not differ from controls in their percent of responses that were correct regulars (slipped); correct irregulars (slept); over-regularizations (sleeped); or regularized (splimmed) or irregularized (splam) past-tenses of novel verbs. In contrast, analyses of response times revealed a striking pattern: subjects with autism were faster at producing regularized (rule-based: slipped, sleeped, splimmed) but not irregularized (memory-based: slept, splam) past-tense forms, relative to controls. The same pattern was seen on a subset of subjects matched on both age and nonverbal (performance) IQ. The observed pattern is consistent with a recent study that also reports normal accuracy but faster-than-normal response times in autism for receptive grammatical processing (Just et al., 2004).

It is known that the adult visual memory system is fractionable into functionally independent cognitive subsystems, selectively susceptible to brain damage. In addition, there have been hints from studies with individuals with autism that these cognitive subsystems can fractionate developmentally. However, there has been a paucity of systematic investigations. The present study involves the analysis of visual memory of a population of individuals with autism and age- and VIQ-matched comparison individuals. The individuals with autism presented selective impairments in face recognition in comparison to both the age- and VIQ-matched comparison populations. In addition, they were impaired relative to the age-matched comparison group on recognition memory for potential agents (i.e. objects capable of self-propelled motion) whether they were living (cats and horses) or non-living (motorbikes). In contrast, they were selectively superior relative to the VIQ-matched comparison group on recognition memory for such objects as topographical stimuli (buildings) and leaves that clearly do not have agency. The data is interpreted in terms of reduced sensitivity to agency cues in individuals with autism and general information processing capacity.

The uneven profile of performance on standard assessments of intelligence and the high incidence of savant skills have prompted interest in the nature of intelligence in autism. The present paper reports the first group study of speed of processing in children with autism (IQ 1 SD below average) using an inspection time task. The children with autism showed inspection times as fast as an age-matched group of young normally developing children (IQ 1 SD above average). They were also significantly faster than mentally handicapped children without autism of the same age, even when these groups were pairwise matched on Wechsler IQ. To the extent that IT tasks tap individual differences in basic processing efficiency, children with autism in this study appear to have preserved information processing capacity despite poor measured IQ. These findings have implications for the role of general and specific cognitive systems in knowledge and skill acquisition: far from showing that children with autism are unimpaired, we suggest that our data may demonstrate the vital role of social insight in the development of manifest "intelligence."

Individuals with autism spectrum disorder have impaired ability to use context, which may manifest as alterations of relatedness within the semantic network. However, impairment in context use may be more difficult to detect in high-functioning adults with ASD. To test context use in this population, we examined the influence of context on memory by using the "false memory" test. In the false memory task, lists of words were presented to high-functioning subjects with ASD and matched controls. Each list consists of words highly related to an index word not on the list. Subjects are then given a recognition test. Positive responses to the index words represent false memories. We found that individuals with ASD are able to discriminate false memory items from true items significantly better than are control subjects. Memory in patients with ASD may be more accurate than in normal individuals under certain conditions. These results also suggest that semantic representations comprise a less distributed network in high-functioning adults with ASD. Furthermore, these results may be related to the unusually high memory capacities found in some individuals with ASD. Research directed at defining the range of tasks performed superiorly by high-functioning individuals with ASD will be important for optimal vocational rehabilitation.

An aspect of cognitive functioning in autistic children was investigated by comparing their performance on the Children's Embedded Figures Test with that of MA-matched normal and MA- and CA-matched mentally retarded non-autistic children. The autistic children were significantly more competent at this task than either group of control children, and also showed qualitatively different strategies. Since the performance of the autistic children was better than predicted from MA and commensurate with CA, it can be regarded as an islet of ability. This finding is discussed in terms of orientation and visualization factors involved in visuo-spatial abilities and is also related to cognitive deficit.

This study investigated self-consciousness in autism. An incidental memory task was conducted on 18 adults with high-functioning autism and 18 normal comparison subjects. Three kinds of orienting questions (phonological, semantic, and self-referent, i.e., "Does the word describe you?") were asked about target words (adjectives for personality traits) in order to induce different types of processing. This was followed by an unexpected recognition test. While semantic processing resulted in better memory than phonological processing in both groups, self-referent processing yielded better memory performance than semantic processing in the comparison group but not in the autistic group. The results suggest deficits in self-consciousness in individuals with autism.

A multi-modal abnormality in the integration of parts and whole has been proposed to account for a bias toward local stimuli in individuals with autism. In the current experiment, we examined the utility of hierarchical models in characterising musical information processing in autistic individuals. Participants were 13 high-functioning individuals with autism and 13 individuals of normal intelligence matched on chronological age, nonverbal IQ, and laterality, and without musical experience. The task consisted of same-different judgements of pairs of melodies. Differential local and global processing was assessed by manipulating the level, local or global, at which modifications occurred. No deficit was found in the two measures of global processing. In contrast, the clinical group performed better than the comparison group in the detection of change in nontransposed, contour-preserved melodies that tap local processing. These findings confirm the existence of a "local bias" in music perception in individuals with autism, but challenge the notion that it is accounted for by a deficit in global music processing. The present study suggests that enhanced processing of elementary physical properties of incoming stimuli, as found previously in the visual modality, may also exist in the auditory modality.

In the present study, copying tasks were used to assess hierarchical aspects of visual perception in a group of 10 nonsavant autistic individuals with normal intelligence. In Experiment 1, the hierarchical order of graphic construction and the constancy of this order were measured for the copying of objects and nonobjects. In comparison to control participants, autistic individuals produced more local features at the start of the copying. However, they did not differ from controls with respect to graphic constancy. Experiment 2 measured the effect of geometrical impossibility on the copying of figures. Results revealed that autistic individuals were less affected by figure impossibility than were controls. Therefore, these experiments seem to support the notion of a local bias for visual information processing in individuals with autism. Two interpretations are proposed to account for this effect. According to the hierarchical deficit hypothesis, individuals with autism do not manifest the normal global bias in perceiving scenes and objects. Alternatively, the executive function hypothesis suggests that autism brings about limitations in the complexity of information that can be manipulated in short-term visual memory during graphic planning.

According to predictions from the Weak Central Coherence theory for perceptual processing, persons with autism should display a tendency to focus on minute details rather than on a more general picture. However, the evidence for this theory is not consistent with findings of an enhanced detection of local targets, but a typical global bias. Adolescents with high-functioning autism and CA- (approximately 15 years) and IQ- (approximately 105-110) matched typically developing adolescents were administered a series of global-local visual tasks, including a traditional task of hierarchical processing, three tasks of configural processing, and a disembedding task that involved rapid perceptual processing. No group differences were found on either the traditional task of hierarchical processing or on tasks of configural processing. However, group differences were found on the disembedding task as the search for embedded, in relation to isolated stimuli, was slower for the typically developing adolescents but similar for the participants with autism. These findings are consistent with other reports of superior performance in detecting embedded figures, but typical performance in global and configural processing among persons with high-functioning autism. Thus, the notions of local bias and global impairment that are part of WCC may need to be reexamined.

Two tasks were used to assess the processing of whole versus parts of objects in a group of high-functioning children and adolescents with autism (N = 11) and a comparison group of typically developing peers (N = 11) matched for chronological age and IQ. In the first task, only the children with autism showed a global advantage, and the two groups showed similar interference between levels. In the second task, the children with autism, despite longer RTs, showed similar performance to the comparison group with regard to the effect of goodness on visual parsing. Contrary to expectations based on the central coherence and hierarchisation deficit theories, these findings indicate intact holistic processing among persons with autism. The implications of these findings are discussed in relation to apparently discrepant evidence from other studies.

Evidence suggests that individuals with autism may not attend to contextual information (conceptual or perceptual) when processing stimuli. We investigated the role of prior knowledge and perspective cues when judging the shape of a slanted circle in individuals with and without autism. Individuals adjusted a shape on a computer screen to appear the same as a slanted circle. Participants in all groups (autistic, moderate learning difficulties, children aged 9 years and adults) exaggerated circularity. Strikingly, however, individuals with autism were unique in exaggerating circularity significantly far less when perspective cues surrounding the slanted circle were eliminated. Prior knowledge that the shape was a slanted circle provoked a strong exaggeration effect in participants without autism, but not in those with autism. Perhaps classifying the stimulus as a 'circle' was sufficient to provoke a strong exaggeration effect in those without (but not with) autism. In this domain, we show that perception in autism may be less influenced by prior knowledge, and therefore less 'top-down'.

Memory tasks were administered to 14 high-functioning individuals with autism and 14 typically developing individuals matched on chronological age and verbal intelligence. The tasks consisted of free and cued recall of 15 semantically unrelated words in 3 encoding conditions: phonological encoding, semantic encoding, and a no encoding orientation. In both groups, semantic orientation led to better free recall than did orientation toward syllabic encoding or absence of orientation. In contrast, semantic cues at retrieval led to better cued recall than phonological cues in typically developing individuals, whereas both types of cue had the same effect in prompting cued recall for individuals with autism. These findings are incompatible with the hypothesis of an amnesic deficit and do not support the notion of executive or semantic deficits in the memory problems of autistic individuals, at least for those with a high level of functioning. It is proposed that these findings can be accounted for by enhanced phonological processing in autism. This interpretation is consistent with other findings of enhanced processing of low-level perceptual information in the visual and auditory modality in autism.

We report here the case study of a patient (E.C.) with an Asperger syndrome, or autism with quasinormal intelligence, who shows an outstanding ability for three-dimensional drawing of inanimate objects (savant syndrome). An assessment of the subsystems proposed in recent models of object recognition evidenced intact perceptual analysis and identification. The initial (or primal sketch), viewer-centered (or 2-1/2-D), or object-centered (3-D) representations and the recognition and name levels were functional. In contrast, E.C.'s pattern of performance in three different types of tasks converge to suggest an anomaly in the hierarchical organization of the local and global parts of a figure: a local interference effect in incongruent hierarchical visual stimuli, a deficit in relating local parts to global form information in impossible figures, and an absence of feature-grouping in graphic recall. The results are discussed in relation to normal visual perception and to current accounts of the savant syndrome in autism.

The performance of children with and without autism was compared in object-based positive and negative priming tasks within a visual search procedure. Object-based positive and negative priming effects were found in both groups of children. This result provides the first evidence for the activation of object-based representations during visual search task performance and further supports the notion that both excitatory and inhibitory guidance mechanisms are involved in target location in visual search. The children with autism were overall better than the typically developing children at visual search, thus replicating demonstrations of superior discrimination in autism. Furthermore, there was no difference between the magnitude of the positive nor the negative priming effects of the groups. This finding suggests that excitatory and inhibitory control operate comparably in autism and normal development. These results are discussed in the light of the superior ability of individuals with autism to discriminate between items. More specifically, it is argued that superior discrimination in autism does not result from enhanced top-down excitatory and inhibitory control.

Objective: Determine if existing norms for Wechsler, RPM and PPVT are actually equivalent in non-autistics, and in autistic children and adults. Design/Methods: Adults: 8 autistics and 17 Aspergers (AS) received WAIS-III+RPM, 5 autistics and 13 AS received WAIS-III+PPVT, and were compared to 19 non-autistic adults tested with the three instruments. Children: 41 autistics and 20 AS received WISC-III+RPM; 30 autistics and 20 AS received WISC-III+PPVT, and were compared to the test norms. Conclusions: Assessment of intelligence in PDDs results in dramatically different levels according to the test given. A significant proportion of low-functioning autistics move into the high-functioning range when tested with two specific instruments. These results have important consequences for matching strategies in empirical design, and in understanding autistic intelligence.

Recent studies have suggested that children with autism perform better than matched controls on visual search tasks and that this stems from a superior visual discrimination ability. This study assessed whether these findings generalize from children to adults with autism. Experiments 1 and 2 showed that, like children, adults with autism were superior to controls at searching for targets. Experiment 3 showed that increases in target-distractor similarity slowed the visual search performance of the control group significantly more than that of the autism group, suggesting that the adults with autism have a superior visual discrimination ability. Thus, these experiments replicate in adults previous findings in children with autism. Superior unique item detection in adults with autism, stemming from enhanced discrimination, is discussed in the light of the possible role of stimulus processing disturbances in the disorder in general.

Howe et al. suggest that most talents can be explained in terms of practice and other environmental effects, and only exceptionally by innate factors. This commentary provides an illustration of one such exception: performance on the Embedded Figures Test by people with autism and their relatives... Innate talents may exist in the sense that : (1) individual differences in a special ability may be partly genetic; and (2) some attributes are only possessed by a minority of individuals.

Systematic variations of the block design task were given to 20 autistic, 33 normal and 12 mildly retarded subjects. Designs were contrasted which were either "whole" or segmented, rotated or unrotated, and which did or did not contain obliques. Only segmentation, but neither of the spatial orientation factors, revealed a significant group difference. Autistic subjects, regardless of age and ability, performed better than controls when presented with unsegmented designs. This result suggests that they need less of the normally required effort to segment a gestalt, and thus supports the hypothesis of weak central coherence as a characteristic of information processing in autism.