Visual form-processing deficits in autism

People with autism have a number of reported deficits in object recognition and global processing. Is there a low-level spatial integration deficit associated with this? We measured spatial-form-coherence detection thresholds using a Glass stimulus in a field of random dots, and compared performance to a similar motion-coherence task. A coherent visual patch was depicted by dots separated by a rotational transformation in space (form) or space-time (motion). To measure parallel visual integration, stimuli were presented for only 250 ms. We compared detection thresholds for children with autism, children with Asperger syndrome, and a matched control group. Children with autism showed a significant form-coherence deficit and a significant motion-coherence deficit, while the performance of the children with Asperger syndrome did not differ significantly from that of controls on either task.     

Individual differences in (non-visual) processing style predict the face inversion effect

Recent research suggests that individuals with relatively weak global precedence (i.e., a smaller propensity to view visual stimuli in a configural manner) show a reduced face inversion effect (FIE). Coupled with such findings, a number of recent studies have demonstrated links between an advantage for feature-based processing and the presentation of traits associated with autism among the general population. The present study sought to bridge these findings by investigating whether a relationship exists between the possession of autism-associated traits (i.e., as indicated by individuals'"autism quotient" [(AQ) and the size of the FIE. Participants completed an on-line study in which the AQ was measured prior to a standard face recognition task where half of the faces were inverted at test. The results confirmed that higher AQ levels were predictive of smaller FIEs. Implications for a common underlying factor relating to processing orientation are discussed.     

Attributing social and physical meaning to ambiguous visual displays in individuals with higher-functioning autism spectrum disorders

The weak central coherence (WCC) account of autism characterizes the learning style of individuals with this condition as favoring localized and fragmented (to the detriment of global and integrative) processing of information. This pattern of learning is thought to lead to deficits in aspects of perception (e.g., face processing), cognition, and communication (e.g., focus on disjointed details rather than "gist" or context), ultimately leading to social impairments. This study was carried out to examine whether WCC applies to social and to non-social aspects of learning alike, or, alternatively, some areas of learning (e.g., physical reasoning) are spared in autism. classic social animation as quantified in the Social Attribution Task (SAT) () and a novel animation involving physical reasoning (the Physical Attribution Task; PAT) were used to test the domain specificity of the WCC hypothesis. A pilot study involving a reference group of typically developing young adults and a group of individuals with higher-functioning autism spectrum disorders (ASDs) revealed gender differences in the reference group in regards to performance on the PAT (males outperformed females). In a follow-up case-control comparison involving only males where the ASD group was matched on age and IQ to a typically developing (TD) group of children, adolescents, and adults, the ASD group showed lower SAT scores and comparable PAT scores relative to the TD group. The interaction of diagnostic group by task was highly significant, with little overlap between the groups in the distributions of SAT minus PAT scores. These results indicated preserved integrative skills in the area of physical attribution in the ASD group, thus failing to support the WCC account as a domain-independent (or more general) model of learning in autism, while highlighting the centrality of the social deficits in the characterization of learning style in the autism spectrum disorders.     

Configural and local processing of faces in children with Williams syndrome

Three experiments investigated face processing in children with Williams syndrome (WS). In Experiment 1, the ability to discriminate different aspects of faces was compared between WS subjects and a group of children individually matched for chronological age (CA-matches) and another group matched for mental age (MA-matches). In Experiments 2 and 3, the ability to process the local and configural aspects of geometrical patterns and faces was assessed within the same groups of subjects. The results indicated that the WSs' overall performance on face recognition was below that of the CA-matches, but similar to that of the MA-matches. This study revealed in addition that the CA- and MA-matches showed a bias toward a configural mode of face and geometrical shape processing, whereas children with WS did not show any bias. These findings suggest that face processing undergoes an abnormal developmental course in WS.     

Global and local processing in adult humans (Homo sapiens), 5-year-old children (Homo sapiens), and adult cotton-top tamarins (Saguinus oedipus)

This study compared adults (Homo sapiens), young children (Homo sapiens), and adult tamarins (Saguinus oedipus) while they discriminated global and local properties of stimuli. Subjects were trained to discriminate a circle made of circle elements from a square made of square elements and were tested with circles made of squares and squares made of circles. Adult humans showed a global bias in testing that was unaffected by the density of the elements in the stimuli. Children showed a global bias with dense displays but discriminated by both local and global properties with sparse displays. Adult tamarins' biases matched those of the children. The striking similarity between the perceptual processing of adult monkeys and humans diagnosed with autism and the difference between this and normatively developing human perception is discussed.     

Early processing of emotional faces in children with autism: An event-related potential study

Social deficits are one of the most striking manifestations of autism spectrum disorders (ASDs). Among these social deficits, the recognition and understanding of emotional facial expressions has been widely reported to be affected in ASDs. We investigated emotional face processing in children with and without autism using event-related potentials (ERPs). High-functioning children with autism (n = 15, mean age = 10.5 ± 3.3 years) completed an implicit emotional task while visual ERPs were recorded. Two groups of typically developing children (chronological age-matched and verbal equivalent age-matched [both ns = 15, mean age = 7.7 ± 3.8 years]) also participated in this study. The early ERP responses to faces (P1 and N170) were delayed, and the P1 was smaller in children with autism than in typically developing children of the same chronological age, revealing that the first stages of emotional face processing are affected in autism. However, when matched by verbal equivalent age, only P1 amplitude remained affected in autism. Our results suggest that the emotional and facial processing difficulties in autism could start from atypicalities in visual perceptual processes involving rapid feedback to primary visual areas and subsequent holistic processing.     

Enhanced perceptual processing of speech in autism

Theories of autism have proposed that a bias towards low-level perceptual information, or a featural/surface-biased information-processing style, may compromise higher-level language processing in such individuals. Two experiments, utilizing linguistic stimuli with competing low-level/perceptual and high-level/semantic information, tested processing biases in children with autism and matched controls. Whereas children with autism exhibited superior perceptual processing of speech relative to controls, and showed no evidence of either a perceptual or semantic processing bias, controls showed a tendency to process speech semantically. The data provide partial support to the perceptual theories of autism. It is additionally proposed that the pattern of results may reflect different patterns of attentional focusing towards single or multiple stimulus cues in speech between children with autism and controls.     

Autism: Hard to Switch from Details to the Whole

It has long been proposed that individuals with autism exhibit a superior processing of details at the expense of an impaired global processing. This theory has received some empirical support, but results are mixed. In this research we have studied local and global processing in ASD and Typically Developing children, with an adaptation of the Navon task, designed to measure congruency effects between local and global stimuli and switching cost between local and global tasks. ASD children showed preserved global processing; however, compared to Typically Developing children, they exhibited more facilitation from congruent local stimuli when they performed the global task. In addition, children with ASD had more switching cost than Typically Developing children only when they switched from the local to the global task, reflecting a specific difficulty to disengage from local stimuli. Together, results suggest that ASD is characterized by a tendency to process local details, they benefit from the processing of local stimuli at the expense of increasing cost to disengage from local stimuli when global processing is needed. Thus, this work demonstrates experimentally the advantages and disadvantages of the increased local processing in children with ASD.     

Visual working memory for global,object, and part-based information

We investigated visual working memory for novel objects and parts of novel objects. After a delay period, participants showed strikingly more accurate performance recognizing a single whole object than the parts of that object. This bias to remember whole objects, rather than parts, persisted even when the division between parts was clearly defined and the parts were disconnected from each other so that, in order to remember the single whole object, the participants needed to mentally combine the parts. In addition, the bias was confirmed when the parts were divided by color. These experiments indicated that holistic perceptual-grouping biases are automatically used to organize storage in visual working memory. In addition, our results suggested that the bias was impervious to top-down consciously directed control, because when task demands were manipulated through instruction and catch trials, the participants still recognized whole objects more quickly and more accurately than their parts. This bias persisted even when the whole objects were novel and the parts were familiar. We propose that visual working memory representations depend primarily on the global configural properties of whole objects, rather than part-based representations, even when the parts themselves can be clearly perceived as individual objects. This global configural bias beneficially reduces memory load on a capacity-limited system operating in a complex visual environment, because fewer distinct items must be remembered.     

Hierarchical forms processing in adults and children

Two experiments examined child and adult processing of hierarchical stimuli composed of geometric forms. Adults (ages 18-23 years) and children (ages 7-10 years) performed a forced-choice task gauging similarity between visual stimuli consisting of large geometric objects (global level) composed of small geometric objects (local level). The stimuli spatial arrangement was manipulated to assess child and adult reaction times and predisposition toward local or global form categorization under two distinct trial conditions, with varied density of the local forms comprising the global forms. In Experiment 1, children and adults were presented with common, simple geometric shape hierarchical forms composed of ovals and rectangles. In Experiment 2, adults were presented with hierarchical forms composed of the simple geometric shapes, ovals and rectangles, and additional novel complex geometric shapes, “posts” and “arches.” Results show a clear increase of global processing bias across the age ranges of the individuals in the study, with children at 10 years performing similarly to adults on the simple stimuli. In addition, adults presented with the novel complex geometric shapes showed a significant reduction in global processing bias, indicating that form novelty and complexity lead to additional attention to local features in categorization tasks.     

Pleasant emotional induction broadens the visual world of young children

These experiments aimed at studying the influence of emotional context on global/local visual processing in children. Children 5 years old, known to present an immature global visual bias, and 8 years old, known to pay attention predominantly to global information, were placed in either a neutral or pleasant emotional context and subsequently presented with a global/local visual judgement task. As with previous findings for adults, both age groups presented a pronounced perceptual bias toward global information following exposure to emotionally pleasant pictures. Interestingly, younger children, who do not present a global bias during the neutral exposure, presented the same preference for global information as older children when exposed to the pleasant context. These findings indicate that emotion may strongly affect visual perception in children, with important implications for educational practice and models of cognition.     

Pleasant emotional induction broadens the visual world of young children

These experiments aimed at studying the influence of emotional context on global/local visual processing in children. Children 5 years old, known to present an immature global visual bias, and 8 years old, known to pay attention predominantly to global information, were placed in either a neutral or pleasant emotional context and subsequently presented with a global/local visual judgement task. As with previous findings for adults, both age groups presented a pronounced perceptual bias toward global information following exposure to emotionally pleasant pictures. Interestingly, younger children, who do not present a global bias during the neutral exposure, presented the same preference for global information as older children when exposed to the pleasant context. These findings indicate that emotion may strongly affect visual perception in children, with important implications for educational practice and models of cognition.     

Is anyone looking at me? Direct gaze detection in children with and without autism

Atypical processing of eye contact is one of the significant characteristics of individuals with autism, but the mechanism underlying atypical direct gaze processing is still unclear. This study used a visual search paradigm to examine whether the facial context would affect direct gaze detection in children with autism. Participants were asked to detect target gazes presented among distracters with different gaze directions. The target gazes were either direct gaze or averted gaze, which were either presented alone (Experiment 1) or within facial context (Experiment 2). As with the typically developing children, the children with autism, were faster and more efficient to detect direct gaze than averted gaze, whether or not the eyes were presented alone or within faces. In addition, face inversion distorted efficient direct gaze detection in typically developing children, but not in children with autism. These results suggest that children with autism use featural information to detect direct gaze, whereas typically developing children use configural information to detect direct gaze.     

视觉正常的自闭症儿童双眼注视点间距的特点及其意义

视网膜上物象对应的外在注视点之间的距离, 即双眼注视点间距(distance of binoculars point of regard, DBPR)在自闭症谱系障碍(autism spectrum disorders, ASD)个体上存在异常的表现, 而ASD个体伴随较高的斜视发病率, 可能会对其双眼注视点间距产生影响。研究采用正弦曲线平滑追踪任务范式, 探索视觉正常的ASD儿童在动态刺激加工过程中DBPR的鉴别意义。结果发现, ASD儿童DBPR过大且具有跨任务类型的稳定性, 且与斜视无关。DBPR在大振幅、快速度的条件下具有优良的鉴别力, 并与自闭症行为量表总分以及感知觉维度显著正相关。结果表明, 双眼注视点间距具有良好的鉴别价值。     

“Hunting with a knife and … fork”: Examining central coherence in autism,attention deficit/hyperactivity disorder,and typical development with a linguistic task

A local processing bias, referred to as “weak central coherence,” has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control. We present a brief and easy-to-administer test of coherence requiring global sentence completions. We report results from three studies assessing (a) 176 typically developing (TD) 8- to 25-year-olds, (b) individuals with ASD and matched controls, and (c) matched groups with ASD or attention deficit/hyperactivity disorder (ADHD). The results suggest that the Sentence Completion Task can reveal individual differences in cognitive style unrelated to IQ in typical development, that most (but not all) people with ASD show weak coherence on this task, and that performance is not related to inhibitory control. The Sentence Completion Task was found to be a useful test instrument, capable of tapping local processing bias in a range of populations.     

Abnormalities in visual processing amongst students with body image concerns

Individuals with body dysmorphic disorder (BDD) appear to possess abnormalities in the way they observe and discriminate visual information. A pre-occupation with perceived defects in appearance has been attributed to a local visual processing bias. We studied the nature of visual bias in individuals who may be at risk of developing BDD – those with high body image concerns (BICs) – by using inverted stimulus discrimination. Inversion disrupts global, configural information in favor of local, feature-based processing. 40 individuals with high BIC and 40 low BIC controls performed a discrimination task with upright and inverted faces, bodies, and scenes. Individuals with high BIC discriminated inverted faces and bodies faster than controls, and were also more accurate when discriminating inverted bodies and scenes. This reduction in inversion effect for high BIC individuals may be due to a stimulus-general local, detail-focused processing bias, which may be associated with maladaptive fixation on small features in their appearance.     

Embedded figures detection in autism and typical development: preliminary evidence of a double dissociation in relationships with visual search

Individuals with autism show relatively strong performance on tasks that require them to identify the constituent parts of a visual stimulus. This is assumed to be the result of a bias towards processing the local elements in a display that follows from a weakened ability to integrate information at the global level. The results of the current study showed that, among children with autism, ability to locate a figure embedded in a larger stimulus was only related to performance on visual search trials where the target was identified by a unique perceptual feature. In contrast, control children's embedded figures performance was specifically related to their performance on visual search trials where the target was defined by a conjunction of features. This double dissociation suggests that enhanced performance on perceptual tasks by children with autism is not simply a consequence of a quantitative difference in ability to engage in global processing.     

Developmental changes in the processing of hierarchical shapes continue into adolescence

The present study was designed to trace the normal development of local and global processing of hierarchical visual forms. We presented pairs of hierarchical shapes to children and adults and asked them to indicate whether the two shapes were the same or different at either the global or the local level. In Experiments 1 (6-year-olds, 10-year-olds, adults) and 2 (10-year-olds, 14-year-olds, adults), we presented stimuli centrally. All age groups responded faster on global trials than local trials (global precedence effect), but the bias was stronger in children and diminished to the adult level between 10 and 14 years of age. In Experiment 3 (10-year-olds, 14-year-olds, adults), we presented stimuli in the left or right visual field so that they were transmitted first to the contralateral hemisphere. All age groups responded faster on local trials when stimuli were presented in the right visual field (left hemisphere); reaction times on global trials were independent of visual field. The results of Experiment 3 suggest that by 10 years of age the hemispheres have adult-like specialization for the processing of hierarchical shapes, at least when attention is directed to the global versus local level. Nevertheless, their greater bias in Experiments 1 and 2 suggests that 10-year-olds are less able than adults to modulate attention to the output from local versus global channels-perhaps because they are less able to ignore distractors and perhaps because the cerebral hemispheres are less able to engage in parallel processing.     

Atypical updating of face representations with experience in children with autism

Face identity aftereffects are significantly diminished in children with autism relative to typical children, which may reflect reduced perceptual updating with experience. Here, we investigated whether this atypicality also extends to non‐face stimulus categories, which might signal a pervasive visual processing difference in individuals with autism. We used a figural aftereffect task to measure directly perceptual updating following exposure to distorted upright faces, inverted faces and cars, in typical children and children with autism. A size‐change between study and test stimuli limited the likelihood that any processing atypicalities reflected group differences in adaptation to low‐level features of the stimuli. Results indicated that, relative to typical children, figural aftereffects for upright faces, but not inverted faces or cars, were significantly attenuated in children with autism. Moreover, the group difference was amplified when we isolated the ‘face‐selective’ component of the aftereffect, by partialling out the mid‐level shape adaptation common to upright and inverted face stimuli. Notably, the aftereffects of typical children were disproportionately larger for upright faces than for inverted faces and cars, but the magnitude of aftereffects of autistic children was not similarly modulated according to stimulus category. These findings are inconsistent with a pervasive adaptive coding atypicality relative to typical children, and suggest that reduced perceptual updating may constitute a high‐level, and possibly face‐selective, visual processing difference in children with autism.     

听写困难儿童的整体字形加工特点

听写困难是指儿童能够认读不能听写的现象。本研究以部件启动和整字启动任务中的探测字命名反应时差值,作为整体字形加工水平的指标,间接考察了听写困难儿童的整体字形加工特点。结果发现,听写对照组被试的整体字形加工在呈现时间为75 ms和300 ms时发生,而在150 ms时没有发生;听写困难组被试的整体字形加工仅在75 ms时发生,而在150 ms和300 ms时未发生。两组被试在75 ms时的整体字形加工水平之间没有显著差异。结果表明,听写困难被试仅仅在早期知觉阶段存在整体字形加工,而在词汇加工阶段的整体字形加工缺乏或延迟。