Global and local visual processing in autism: An objective assessment approach

It's all in the timing: Delayed feedback in autism may weaken predictive mechanisms during contour integration

Humans rely on predictive mechanisms during visual processing to efficiently resolve incomplete or ambiguous sensory signals. While initial low-level sensory data are conveyed by feedforward connections, feedback connections are believed to shape sensory processing through conveyance of statistical predictions based on prior exposure to stimulus configurations. Individuals with autism spectrum disorder (ASD) show biases in stimulus processing toward parts rather than wholes, suggesting their sensory processing may be less shaped by statistical predictions acquired through prior exposure to global stimulus properties. Investigations of illusory contour (IC) processing in neurotypical (NT) adults have established a well-tested marker of contour integration characterized by a robust modulation of the visually evoked potential (VEP) - the IC-effect - that occurs over lateral occipital scalp during the timeframe of the N1 component. Converging evidence strongly supports the notion that this IC-effect indexes a signal with significant feedback contributions. Using high-density VEPs, we compared the IC-effect in 6-17-year-old children with ASD (n=32) or NT development (n=53). Both groups of children generated an IC-effect that was equivalent in amplitude. However, the IC-effect notably onset 21ms later in ASD, even though timing of initial VEP afference was identical across groups. This suggests that feedforward information predominated during perceptual processing for 15% longer in ASD compared to NT children. This delay in the feedback dependent IC-effect, in the context of known developmental differences between feedforward and feedback fibers, suggests a potential pathophysiological mechanism of visual processing in ASD, whereby ongoing stimulus processing is less shaped by statistical prediction mechanisms.

Altered Allocation of Vertical Attention in Individuals With Autism Spectrum Disorder

BACKGROUND

Typical adults most frequently orient their attention to other people's eyes, whereas individuals with autism spectrum disorder (ASD) orient their attention to other people's mouths. Typical adults also reveal visuospatial biases on tasks such as vertical and horizontal line bisections. Therefore, the difference in face viewing might be related to a more general group difference in the allocation of vertical attention.

OBJECTIVE

To use vertical line bisection and quadrisection tasks to evaluate whether individuals with ASD have a more downward-oriented vertical attentional bias than do typical individuals.

METHOD

We recruited 20 individuals with ASD and 20 control participants matched for age (6-23 years), IQ, and sex. We asked the individuals to bisect and quadrisect lines on the top and bottom when the vertical lines were placed at the intersection of their right, left, and center egocentric sagittal planes and their coronal plane. The distances from the true midpoint and quadripoint were measured, and between-group performances were compared.

RESULTS

No significant difference was found between the ASD and control groups for vertical line bisections or lower line quadrisections. However, when the ASD group was compared with the control group for higher line quadrisections, the ASD group exhibited a greater upward deviation.

CONCLUSION

There is no downward vertical attentional spatial bias associated with ASD that could help to explain these individuals' attentional bias toward the mouth. However, additional studies are required to learn if this atypical upward vertical attentional bias might account for some of the symptoms and signs associated with ASD.

[Formula: see text] A cross-cultural study of visual attention in autism spectrum disorder

Differences in visual attention have been documented in ASD, and appear linked to clinical symptoms. However, most research has been conducted in Western cultures. Because striking differences in visual attention patterns have been documented in other cultures, it is important to understand how culture may influence attentional patterns in ASD. This study compared differences in visual attention in ASD across Western and East Asian cultures, where differences in attention to contextual and global information have been repeatedly demonstrated, to investigate potential culturally-specific ASD phenotypes. One hundred thirty-two total participants included individuals with ASD (n = 24) and controls (n = 47) from Hong Kong (HK), along with a previously studied group of age- and IQ-comparable participants from the United States (n = 26 ASD; n = 35 control). Gaze was tracked while participants completed two narrative tasks that differed in social-emotional complexity. Proportions of fixations to face, bodies, and setting were examined across groups using linear mixed-effect models and a series of growth curve models. Cultural differences were found across tasks and groups. Both the ASD and control HK groups attended more to global contextual setting information, more to the body regions, and less toward faces of characters compared to US groups. Growth curve models indicated that these differences attenuated over time in certain stimuli. ASD-related effects were only observed in the more complex stimuli depicting characters with ambiguous facial expressions. Findings indicate a notable cultural influence on visual attention patterns in ASD, and underscore the importance of stimuli complexity in differentiating cultural versus diagnostic effects on attentional styles.

Severely Attenuated Visual Feedback Processing in Children on the Autism Spectrum

Individuals on the autism spectrum often exhibit atypicality in their sensory perception, but the neural underpinnings of these perceptual differences remain incompletely understood. One proposed mechanism is an imbalance in higher-order feedback re-entrant inputs to early sensory cortices during sensory perception, leading to increased propensity to focus on local object features over global context. We explored this theory by measuring visual evoked potentials during contour integration as considerable work has revealed that these processes are largely driven by feedback inputs from higher-order ventral visual stream regions. We tested the hypothesis that autistic individuals would have attenuated evoked responses to illusory contours compared with neurotypical controls. Electrophysiology was acquired while 29 autistic and 31 neurotypical children (7-17 years old, inclusive of both males and females) passively viewed a random series of Kanizsa figure stimuli, each consisting of four inducers that were aligned either at random rotational angles or such that contour integration would form an illusory square. Autistic children demonstrated attenuated automatic contour integration over lateral occipital regions relative to neurotypical controls. The data are discussed in terms of the role of predictive feedback processes on perception of global stimulus features and the notion that weakened "priors" may play a role in the visual processing anomalies seen in autism.SIGNIFICANCE STATEMENT Children on the autism spectrum differ from typically developing children in many aspects of their processing of sensory stimuli. One proposed mechanism for these differences is an imbalance in higher-order feedback to primary sensory regions, leading to an increased focus on local object features rather than global context. However, systematic investigation of these feedback mechanisms remains limited. Using EEG and a visual illusion paradigm that is highly dependent on intact feedback processing, we demonstrated significant disruptions to visual feedback processing in children with autism. This provides much needed experimental evidence that advances our understanding of the contribution of feedback processing to visual perception in autism spectrum disorder.

Youth and Caregivers' Perspective on Teens Engaged as Mentors (TEAM): An Inclusive Peer Mentoring Program for Autistic Adolescents

Past studies indicate that many autistic youth benefit from support with developing social relationships, exploring leadership opportunities, and engaging in post-secondary education. Teens Engaged as Mentors (TEAM) is an innovative mentoring program that provides socialization and community engagement opportunities in a safe environment for youth with and without autism. This qualitative study explored how participants and their caregivers perceived participation in TEAM. Stakeholder focus groups were conducted annually from 2016 to 2020 with 16 autistic mentees (ages 9-13), 30 autistic and neurotypical mentors (ages 14-21), and 30 caregivers. Participants reported enjoying TEAM because of increased socialization opportunities, which promoted friendships and openness toward others. Caregivers reported growth in their children's social skills and confidence throughout their participation.

Gauging facial feature viewing preference as a stable individual trait in autism spectrum disorder

Eye tracking provides insights into social processing deficits in autism spectrum disorder (ASD), especially in conjunction with dynamic, naturalistic free-viewing stimuli. However, the question remains whether gaze characteristics, such as preference for specific facial features, can be considered a stable individual trait, particularly in those with ASD. If so, how much data are needed for consistent estimations? To address these questions, we assessed the stability and robustness of gaze preference for facial features as incremental amounts of movie data were introduced for analysis. We trained an artificial neural network to create an object-based segmentation of naturalistic movie clips (14 s each, 7410 frames total). Thirty-three high-functioning individuals with ASD and 36 age- and IQ-equated typically developing individuals (age range: 12-30 years) viewed 22 Hollywood movie clips, each depicting a social interaction. As we evaluated combinations of one, three, five, eight, and 11 movie clips, gaze dwell times on core facial features became increasingly stable at within-subject, within-group, and between-group levels. Using a number of movie clips deemed sufficient by our analysis, we found that individuals with ASD displayed significantly less face-centered gaze (centralized on the nose; p < 0.001) but did not significantly differ from typically developing participants in eye or mouth looking times. Our findings validate gaze preference for specific facial features as a stable individual trait and highlight the possibility of misinterpretation with insufficient data. Additionally, we propose the use of a machine learning approach to stimuli segmentation to quickly and flexibly prepare dynamic stimuli for analysis. LAY SUMMARY: Using a data-driven approach to segmenting movie stimuli, we examined varying amounts of data to assess the stability of social gaze in individuals with autism spectrum disorder (ASD). We found a reduction in social fixations in participants with ASD, driven by decreased attention to the center of the face. Our findings further support the validity of gaze preference for face features as a stable individual trait when sufficient data are used.

Eye Movements of Spatial Working Memory Encoding in Children with and without Autism: Chunking Processing and Reference Preference

Individuals with autism spectrum disorder (ASD) experience spatial working memory deficits and show different encoding mechanisms from typical developing (TD) peers. To effectively describe the encoding strategies of those with ASD and highlight their characteristics in cognitive processing, we adopted improved change detection tasks and added eye-movement indicators to investigate the chunking function and reference preference of children with and without ASD. The current study included 20 participants with ASD aged 8-16 and 20 TD children matched for age, gender, and intelligence. Experiment 1 used high/low-structured change detection tasks, and eye-movement indexes were recorded as they memorized the locations of the items to investigate spatial chunking strategies. In Experiment 2, changes in eye movement patterns were observed by adding a frame of reference. The results suggested different encoding strategies in ASD and TD individuals. The ASD group showed local processing bias and had difficulty adopting chunking strategies in spatial working memory. Eye-movement analysis suggested that they rarely showed integrated information processing tendency observed in TD children. Moreover, as a compensatory processing, they were more likely to use the frame of reference. In this study, we compared the spatial chunking strategies and reference preference of children with and without ASD, and eye-movement analysis was used to investigate the processing mechanism. These findings are significant for research on cognitive characteristics of ASD and provide a new focus for working memory training in children with ASD. LAY SUMMARY: The current study suggests that children with autism spectrum disorder are poorer at organizing items into chunks in spatial working memory, but rely more on reference frames. If the purpose of location memory is to strengthen the adaptability of children with autism, it should provide them with more clues or references. If it is for the purpose of intervention such as cognitive training, it should guide them to integrate information to improve the basic cognitive processing efficiency. Autism Res 2021, 14: 897-910. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

Social-valence-related increased attention in rett syndrome cynomolgus monkeys: An eye-tracking study

The cognitive phenotypes of Rett syndrome (RTT) remain unclarified compared with the well-defined genetic etiology. Recent clinical studies suggest the eye-tracking method as a promising avenue to quantify the visual phenotypes of the syndrome. The present study explored various aspects of visual attention of the methyl-CpG-binding protein 2 gene mutant RTT monkeys with the eye-tracking procedure. Comprehensive testing paradigms, including social valence comparison (SVC), visual paired comparison (VPC), and social recognition memory (SRM), were utilized to investigate their attentional features to social stimuli with differential valence, the novelty preferences, and short-term recognition memory, respectively. To explore the neurobiological mechanisms underlying the eye-tracking findings, we assessed changes of the brain subregion volumes and neurotransmitter concentrations. Compared with control monkeys, RTT monkeys demonstrated increased viewing on the more salient stare faces than profile faces in the SVC test, and increased viewing on the whole presented images composed of monkey faces in the VPC and SRM tests. Brain imaging revealed reduced bilateral occipital gyrus in RTT monkeys. The exploratory neurotransmitter analyses revealed no significant changes of various neurotransmitter concentrations in the cerebrospinal fluid and blood of RTT monkeys. The eye-tracking results suggested social-valence-related increased attention in RTT monkeys, supplementing the cognitive phenotypes associated with the syndrome. Further investigations from broader perspectives are required to uncover the underlying neurobiological mechanisms. Autism Res 2019, 00: 1-13. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Altered expressions of the methyl-CpG-binding protein 2 (MECP2) gene are usually associated with neurodevelopmental disorders, such as autism spectrum disorders, Rett syndrome (RTT), and so forth. The present eye-tracking study found social-valence-related increased attention in our firstly established MECP2 mutant RTT monkeys. The novel findings supplement the cognitive phenotypes and potentially benefit the behavioral interventions of the RTT syndrome.

Visual search and autism symptoms: What young children search for and co-occurring ADHD matter

Superior visual search is one of the most common findings in the autism spectrum disorder (ASD) literature. Here, we ascertain how generalizable these findings are across task and participant characteristics, in light of recent replication failures. We tested 106 3-year-old children at familial risk for ASD, a sample that presents high ASD and ADHD symptoms, and 25 control participants, in three multi-target search conditions: easy exemplar search (look for cats amongst artefacts), difficult exemplar search (look for dogs amongst chairs/tables perceptually similar to dogs), and categorical search (look for animals amongst artefacts). Performance was related to dimensional measures of ASD and ADHD, in agreement with current research domain criteria (RDoC). We found that ASD symptom severity did not associate with enhanced performance in search, but did associate with poorer categorical search in particular, consistent with literature describing impairments in categorical knowledge in ASD. Furthermore, ASD and ADHD symptoms were both associated with more disorganized search paths across all conditions. Thus, ASD traits do not always convey an advantage in visual search; on the contrary, ASD traits may be associated with difficulties in search depending upon the nature of the stimuli (e.g., exemplar vs. categorical search) and the presence of co-occurring symptoms.

Local and Global Visual Processing in 3-Year-Olds With and Without Autism

Research on visual local and global perception in Autism Spectrum Disorder (ASD) is incomplete in young children. We investigated 35 three-year-old siblings of children with ASD, either diagnosed (n = 12) or not diagnosed (n = 23) with ASD as well as 14 controls with typical development and with no family history of ASD. Data from the local tasks Children's Embedded Figures Test, Hidden Pictures, Figure-Ground and the global tasks Closure and Fragmented Picture Test were collected. Enhanced performance on the local task Hidden Pictures differentiated children with ASD from the other groups. Implications of these results are discussed.