Superior Local Processing Research Articles

Visual search in ADHD, ASD and ASD\u2009+\u2009ADHD: overlapping or dissociating disorders?

Recent debates in the literature discuss commonalities between Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) at multiple levels of putative causal networks. This debate requires systematic comparisons between these disorders that have been studied in isolation in the past, employing potential markers of each disorder to be investigated in tandem. The present study, choose superior local processing, typical to ASD, and increased Intra-Subject Variability (ISV), typical to ADHD, for a head-to-head comparison of the two disorders, while also considering the comorbid cases. It directly examined groups of participants aged 10–13 years with ADHD, ASD with (ASD+) or without (ASD−) comorbid ADHD and a typically developing (TD) group (total N = 85). A visual search task consisting of an array of paired words was designed. The participants needed to find the specific pair of words, where the first word in the pair was the cue word. This visual search task was selected to compare these groups on overall search performance and trial-to-trial variability of search performance (i.e., ISV). Additionally, scanpath analysis was also carried out using Recurrence Quantification Analysis (RQA) and the Multi-Match Model. Results show that only the ASD− group exhibited superior search performance; whereas, only the groups with ADHD symptoms showed increased ISV. These findings point towards a double dissociation between ASD and ADHD, and argue against an overlap between ASD and ADHD.

Individual differences in brain structure and resting brain function underlie cognitive styles: evidence from the Embedded Figures Test.

Cognitive styles can be characterized as individual differences in the way people perceive, think, solve problems, learn, and relate to others. Field dependence/independence (FDI) is an important and widely studied dimension of cognitive styles. Although functional imaging studies have investigated the brain activation of FDI cognitive styles, the combined structural and functional correlates with individual differences in a large sample have never been investigated. In the present study, we investigated the neural correlates of individual differences in FDI cognitive styles by analyzing the correlations between Embedded Figures Test (EFT) score and structural neuroimaging data [regional gray matter volume (rGMV) was assessed using voxel-based morphometry (VBM)] / functional neuroimaging data [resting-brain functions were measured by amplitude of low-frequency fluctuation (ALFF)] throughout the whole brain. Results showed that the increased rGMV in the left inferior parietal lobule (IPL) was associated with the EFT score, which might be the structural basis of effective local processing. Additionally, a significant positive correlation between ALFF and EFT score was found in the fronto-parietal network, including the left inferior parietal lobule (IPL) and the medial prefrontal cortex (mPFC). We speculated that the left IPL might be associated with superior feature identification, and mPFC might be related to cognitive inhibition of global processing bias. These results suggested that the underlying neuroanatomical and functional bases were linked to the individual differences in FDI cognitive styles and emphasized the important contribution of superior local processing ability and cognitive inhibition to field-independent style.

Is superior local processing in the visuospatial domain a function of drawing talent rather than autism spectrum disorder?

This study challenges the prevailing assumption that superior local processing is specific to autism spectrum diagnosis and suggests instead that such processing skill is a function of realistic drawing talent. Fifteen children with autism spectrum disorder (ASD) and 15 without ASD made an observational drawing scored for level of drawing realism and completed 2 tasks that allowed for the assessment of a local processing bias: the Block Design Task in unsegmented and segmented form at three levels of perceptual cohesiveness (minimal, intermediate, and maximal), and the Group Embedded Figures Test. Drawing realism score, not ASD diagnosis, predicted performance on the unsegmented version of the Block Design Task and on the most difficult items—the unsegmented maximally cohesive items. Accuracy on the Group Embedded Figures Test was also more strongly associated with level of drawing realism than ASD diagnosis. Thus, the superior local processing seen in ASD may be due to the drawing talent so often present in those with ASD.

Central Coherence in Full Recovery of Anorexia Nervosa

This study examined central coherence as a possible endophenotype in a large sample of women recovered from anorexia nervosa (rec AN). Recovery was defined by considering physiological, behavioural and psychological variables. A total of 100 rec AN women and 100 healthy women completed the Rey Complex Figure Test, a measure for visual-spatial central coherence. The participants were matched 1:1 for age and educational level. Compared with the healthy control group, the rec AN group showed better accuracy in the copy condition. There was a trend for a local strategy in the rec AN group compared with a global strategy in the healthy control group. This sample of rec AN women showed no inefficiencies in global processing but a superior local processing after full recovery from AN.

Superior Visual Analysis and Imagery in an Autistic Child with Drawing Talent

Two opposing theories have been proposed to account for the strong visuospatial performance often seen in high-functioning individuals with autism. According to the weak central coherence account, individuals with autism show a local processing bias. They have a superior grasp of the local details of a visual display but fail to grasp global aspects of the display (Happé & Frith, 2006). According to the enhanced perceptual functioning account, individuals with autism have superior local processing as well as intact global processing (Mottron & Burack, 2001). We report a case study of J.G., a 10-year-old child of normal intelligence diagnosed with autism. He experienced expressive language delay, but showed special talents in both drawing and visual imagery. Our tests revealed that J.G. had superior local but poor global processing. This pattern of performance provides stronger support for weak central coherence than for enhanced perceptual functioning.

Electromagnetic evidence of altered visual processing in autism

Individuals with autism spectrum disorder (ASD) demonstrate intact or superior local processing of visual-spatial tasks. We investigated the hypothesis that in a disembedding task, autistic individuals exhibit a more local processing style than controls, which is reflected by altered electromagnetic brain activity in response to embedded stimuli and enhanced activity of early visual areas. Ten autistic and ten matched control participants underwent 151-channel whole-head magnetoencephalography. Participants were presented with 400 embedded or isolated letters (‘S’ or ‘H’) and asked to indicate which of the two letters was shown. Performance was equal in both groups, but event-related magnetic fields differed between groups in an early (100–150ms) and a later (350–400ms) time window. In the early time window, autistic individuals differed from control participants in the embedded, but not in the isolated condition, reflecting reduced processing of the irrelevant context in autistic individuals. In the later time window, amplitude differences between the embedded and isolated conditions were measured in control participants only, suggesting that “disembedding” processes were not required in autistic individuals. Source localisation indicated that activity in individuals with ASD peaked in the primary visual cortex in both conditions and time windows indicating an effortless (automatic, bottom-up) local process, whereas activity in controls peaked outside the visual cortex.

Magnocellular visual evoked potential delay with high autism spectrum quotient yields a neural mechanism for altered perception

Everyone has autistic characteristics to a greater or lesser degree, encapsulated in the Autism Spectrum Quotient, a scale that measures the degree to which an adult of normal intelligence displays traits associated with autism spectrum disorders. Recent psychophysical analyses of autism spectrum disorders point to superior local processing, and impaired or ignored global and contextual processing. The aim of this study was to test whether low- and high-scoring individuals on the Autism Spectrum Quotient differ on a measure of local and global processing, motion processing and visual pathway integrity. Fifteen low-scoring individuals and 14 high-scoring individuals derived from a normal population participated in the study. The results indicate that the initial cortical response to the magnocellular afferents is weaker at low contrast in the high autistic tendency group and that a second-order response, reflecting magnocellular activity, demonstrated a delay for high versus low scorers when the parvocellular pathway was also active in response to a high contrast stimulus. High-scoring individuals also demonstrated difficulty in identifying the global components of locally salient hierarchical Navon figures. Furthermore, cross-validated discriminant analysis, using four physiologically and three psychophysically derived parameters, correctly classified 83% of individuals who scored either high or low on the Autism Spectrum Quotient. These findings in the group scoring high on the Autism Spectrum Quotient indicate that a delay in primary visual/prestriate cortical processing of magnocellular input diminishes the advantage of its early arrival to primary visual cortex. This appears to be associated with impaired global visual perception, predicting with high accuracy behavioural tendencies associated with autism spectrum disorders. It has been proposed that perceptual impairment in autism may be attributed to a dysfunction of horizontal connections within early visual areas, presumably parvocellular in nature. However, the timing of such form processing aberrations is much later than the timing of abnormal magnocellular visual processing measured directly here. Thus it is proposed that a magnocellular processing delay decreases the ability of autistic individuals to benefit perceptually from feedback normally associated with the magnocellular advantage.

Impaired Competence for Pretense in Children with Autism: Exploring Potential Cognitive Predictors

Lack of pretense in children with autism has been explained by a number of theoretical explanations, including impaired mentalising, impaired response inhibition, and weak central coherence. This study aimed to empirically test each of these theories. Children with autism (n = 60) were significantly impaired relative to controls (n = 65) when interpreting pretense, thereby supporting a competence deficit hypothesis. They also showed impaired mentalising and response inhibition, but superior local processing indicating weak central coherence. Regression analyses revealed that mentalising significantly and independently predicted pretense. The results are interpreted as supporting the impaired mentalising theory and evidence against competing theories invoking impaired response inhibition or a local processing bias. The results of this study have important implications for treatment and intervention.

Weak central coherence in eating disorders: A step towards looking for an endophenotype of eating disorders

Previous work has found that women with anorexia nervosa and bulimia nervosa have weak coherence. The aim of this study was to examine whether women who had recovered from an eating disorder (ED) also had weak coherence. A total of 42 recovered ED women and 42 healthy women were assessed with a battery of five neuropsychological tests that measure aspects of global or local functioning. The recovered ED group showed superior local processing and poorer global processing than the healthy group. These results are indicative of weak coherence. The finding that weak coherence is a stable characteristic rather than a state effect suggests that it may be an endophenotype for ED.

Central coherence in eating disorders: a systematic review

This review systematically appraised the research evidence for local versus global information processing to test the hypothesis that people with eating disorders (ED) had weak central coherence. Searches on Medline, EMBASE, PsycINFO and ISI Web of Science databases were conducted in November 2006 and subsequently updated in September 2007. Each search was conducted in two steps: (1) neuropsychological tasks measuring central coherence and (2) words related to cognitive functioning in eating disorders. Data were summarized in a meta-analysis if the number of studies for a given test was >5. Data were extracted from 16 studies. Meta-analyses were conducted for four tasks obtaining moderate effect sizes. The majority of studies found global processing difficulties across the ED spectrum. The results are less clear regarding local processing. People with ED have difficulties in global processing. It is less certain as to whether they have superior local processing. Currently, there is insufficient evidence to refute the weak central coherence hypothesis.

Vagaries of Visual Perception in Autism

Three classes of perceptual phenomena have repeatedly been associated with autism spectrum disorder (ASD): superior processing of fine detail (local structure), either inferior processing of overall/global structure or an ability to ignore disruptive global/contextual information, and impaired motion perception. This review evaluates the quality of the evidence bearing on these three phenomena. We argue that while superior local processing has been robustly demonstrated, conclusions about global processing cannot be definitively drawn from the experiments to date, which have generally not precluded observers using more local cues. Perception of moving stimuli is impaired in ASD, but explanations in terms of magnocellular/dorsal deficits do not appear to be sufficient. We suggest that abnormalities in the superior temporal sulcus (STS) may provide a neural basis for the range of motion-processing deficits observed in ASD, including biological motion perception. Such an explanation may also provide a link between perceptual abnormalities and specific deficits in social cognition associated with autism.

Schizotypy and hemisphere function—III: Performance asymmetries on tasks of letter recognition and local-global processing

Two experiments are reported comparing high and low schizotypal normals on divided field tasks of (a) letter recognition and (b) local-global processing. On the former, low schizotypal Ss showed an expected right visual-field superiority, whereas high schizotypal Ss showed the opposite, in that respect resembling schizophrenic patients. A similar reversed asymmetry was found when the two personality types were compared for local and global processing of letter stimuli, high schizotypals being especially unusual in showing superior local processing for stimuli presented in the left visual field. The results are taken as providing further support for the theory of schizotypy put forward in a previous paper.