Jacalyn Guy

An early origin for detailed perception in Autism Spectrum Disorder: biased sensitivity for high-spatial frequency information.

Autistics demonstrate superior performances on several visuo-spatial tasks where local or detailed information processing is advantageous. Altered spatial filtering properties at an early level of visuo-spatial analysis may be a plausible perceptual origin for such detailed perception in Autism Spectrum Disorder. In this study, contrast sensitivity for both luminance and texture-defined vertically-oriented sine-wave gratings were measured across a range of spatial frequencies (0.5, 1, 2, 4 & 8 cpd) for autistics and non-autistic participants. Contrast sensitivity functions and peak frequency ratios were plotted and compared across groups. Results demonstrated that autistic participants were more sensitivity to luminance-defined, high spatial frequency gratings (8 cpd). A group difference in peak distribution was also observed as 35% of autistic participants manifested peak sensitivity for luminance-defined gratings of 4 cpd, compared to only 7% for the comparison group. These findings support that locally-biased perception in Autism Spectrum Disorder originates, at least in part, from differences in response properties of early spatial mechanisms favouring detailed spatial information processing.

The development of luminance- and texture-defined form perception during the school-aged years.

The objective of the present study was to assess the development of luminance- and texture-defined static form perception in school-aged children. This was done using an adapted Landolt-C technique where C-optotypes were defined by either luminance or texture information, the latter necessitating extra-striate neural processing to be perceived. Typically developing children were placed in one of 4 school-age groups (6, 8, 10 and 12-year olds); an adult group was also assessed. The contrast threshold for the correct identification of gap-opening-orientation for C-optotypes defined by either texture- or luminance-contrast was measured. All participants were presented with C-optotypes with gap-openings presented in one of 4 orientations (up, down, left or right). An adaptive staircase procedure was used to measure gap-opening-identification thresholds (minimum luminance- or texture-contrast modulation) for all three conditions and ages. As expected, gap-opening identification sensitivity (1/threshold) increased with age for all conditions. For both luminance-defined conditions, adult-like performance was manifested by 12 years of age. By comparison, at 12 years of age, the sensitivity to texture-defined C-optotypes was significantly lower than that of adults, having increased steadily from the age of 6 years. These results suggest that mechanisms underlying static form perception mature at different ages depending on the physical attribute defining the form. Luminance-defined form perception appears to reach adult-like levels (or plateau) earlier than for texture-defined information, suggesting that the development of mechanisms mediating higher-order form perception persist into adolescence.

The developmental trajectory of contrast sensitivity in autism spectrum disorder.

Autism Spectrum Disorder (ASD) is characterized by a detail‐driven visual processing strategy, evidence for which has been based largely on cross‐sectional studies in small participant groups of limited age ranges. It is therefore unknown when sensitivity to detailed information emerges and develops in ASD. Contrast sensitivity to sinusoidal gratings of different spatial frequencies (0.5, 1, 2, 4, and 8 cycles per degree (cpd)) was measured for 34 participants with ASD and 55 typically developing participants (aged 6–16 years). Cross‐sectional, developmental trajectories were constructed to examine within and between group differences across the range of spatial frequencies tested. Developmental trajectories indicated that sensitivity across low (i.e., 0.5 and 1 cpd) and mid (2 and 4 cpd) spatial frequencies varied by chronological age within each group, with mid frequencies developing at a more significant rate than low frequencies. There was no overall difference between groups in terms of the relationship of sensitivity and age across spatial frequencies, yet the ASD group had an overall lower level of sensitivity. Closer examination revealed that the youngest participants with ASD had a reduced sensitivity for mid frequencies. Moreover, the ASD group showed a statistically significant developmental relationship at 8 cpd, which suggests that a trend for increased sensitivity to early detailed information may manifest beyond the ages tested. These findings demonstrate a differential development of contrast sensitivity for spatial frequencies in ASD and underscore the need to better identify what drives such differences in the “building blocks” of visual perception. Autism Res 2016, 9: 866–878.

Atypical Face Perception in Autism: A Point of View?

Face perception is the most commonly used visual metric of social perception in autism. However, when found to be atypical, the origin of face perception differences in autism is contentious. One hypothesis proposes that a locally oriented visual analysis, characteristic of individuals with autism, ultimately affects performance on face tasks where a global analysis is optimal. The objective of this study was to evaluate this hypothesis by assessing face identity discrimination with synthetic faces presented with and without changes in viewpoint, with the former condition minimizing access to local face attributes used for identity discrimination. Twenty‐eight individuals with autism and 30 neurotypical participants performed a face identity discrimination task. Stimuli were synthetic faces extracted from traditional face photographs in both front and 20° side viewpoints, digitized from 37 points to provide a continuous measure of facial geometry. Face identity discrimination thresholds were obtained using a two‐alternative, temporal forced choice match‐to‐sample paradigm. Analyses revealed an interaction between group and condition, with group differences found only for the viewpoint change condition, where performance in the autism group was decreased compared to that of neurotypical participants. The selective decrease in performance for the viewpoint change condition suggests that face identity discrimination in autism is more difficult when access to local cues is minimized, and/or when dependence on integrative analysis is increased. These results lend support to a perceptual contribution of atypical face perception in autism. Autism Res 2015, 8: 497–506.

Age-related changes in visual and auditory sustained attention in preschool-aged children

Objective: The development of sustained attention in the preschool years is not yet fully understood. Delineating age-related changes of attentional proficiencies and deficiencies is important for understanding atypical developmental trajectories, specifically in neurodevelopmental disorders that are characterized by attentional difficulties. The objective of the current study was to develop preschool-appropriate measures for assessing sustained attention and to chart developmental changes in attention in early childhood. Method: Using adapted computerized paradigms, the present study investigated age-related changes in visual and auditory sustained attention in seventy typically developing children aged 3 to 6 years. Results: The results indicated that similar age-related gains in performance emerged across both visual and auditory attention tasks. Conclusion: The findings suggest that the adapted measures developed in this study are sensitive enough to capture developmental variations in attention performance.

Assessing spatial perception in aging using an adapted Landolt-C technique

This study investigated luminance and texture-defined spatial information processing in normal aging using an adapted Landolt-C technique. Sensitivity to C-target stimuli (optotypes) was measured for four age groups: 18–34, 35–49, 50–64, and 65+ years. Participants indicated optotype gap-opening orientations (up, down, left, or right) at different levels of luminance or texture contrast. Although sensitivity did not differ across age group for the luminance-defined optotypes, sensitivity for texture-defined optotypes for the 65+ years age group was significantly decreased relative to that of the youngest group (18–34 years). Results suggest that age-related changes in visual function can be dissociated at different levels of processing, and may be better defined using stimuli that necessarily depend on higher levels of neural functioning to be perceived.

Training with a three-dimensional multiple object-tracking (3D-MOT) paradigm improves attention in students with a neurodevelopmental condition: a randomized controlled trial

The efficacy of attention training paradigms is influenced by many factors, including the specificity of targeted cognitive processes, accuracy of outcome measures, accessibility to specialized populations, and adaptability to user capability. These issues are increasingly significant when working with children diagnosed with neurodevelopmental conditions that are characterized by attentional difficulties. This study investigated the efficacy of training attention in students with neurodevelopmental conditions using a novel three-dimensional Multiple Object-Tracking (3D-MOT) task. All students (ages 6-18 years) performed the Conners Continuous Performance Task (CPT-3) as a baseline measure of attention. They were then equally and randomly assigned to one of three groups: a treatment group, (3D-MOT); an active control group (visual strategy/math-based game, 2048); and a treatment as usual group. Students were trained on their respective tasks for a total of 15 training sessions over a five-week period and then reassessed on the CPT-3. Results showed that post-training CPT-3 performance significantly improved from baseline for participants in the treatment group only. This improvement indicates that training with 3D-MOT increased attentional abilities in students with neurodevelopmental conditions. These results suggest that training attention with a non-verbal, visual-based task is feasible in a school setting and accessible to atypically developing students with attentional difficulties.

Face perception develops similarly across viewpoint in children and adolescents with and without autism spectrum disorder

Atypical face perception has been associated with the socio-communicative difficulties that characterize autism spectrum disorder (ASD). Growing evidence, however, suggests that a widespread impairment in face perception is not as common as once thought. One important issue arising with the interpretation of this literature is the relationship between face processing and a more general perceptual tendency to focus on local rather than global information. Previous work has demonstrated that when discriminating faces presented from the same view, older adolescents and adults with ASD perform similarly to typically developing individuals. When faces are presented from different views, however, they perform more poorly-specifically, when access to local cues is minimized. In this study, we assessed the cross-sectional development of face identity discrimination across viewpoint using same- and different-view conditions in children and adolescents with and without ASD. Contrary to the findings in adults, our results revealed that all participants experienced greater difficulty identifying faces from different views than from same views, and demonstrated similar age-expected improvements in performance across tasks. These results suggest that differences in face discrimination across views may only emerge beyond the age of 15 years in ASD.

Outcome Measures in Clinical Trials for Fragile X Syndrome: The Search for Sensitive Neurocognitive Assays

Clinical trials of multiple pharmacological agents have thus far had more limited success than hypothesized in demonstrating beneficial treatment effects for children; adolescents; and adults with fragile X syndrome (FXS). Other chapters in this edited volume have summarized potential reasons for these limited successes. Here we focus on evaluating the nature of outcome measures that have been used in clinical trials thus far. We emphasize how future trials of both pharmacological and nonpharmacological interventions will require more sensitive and objective measures of neurocognitive functioning; to be developed in close collaboration with stakeholder groups and researchers working on the cognitive; neural; and behavioral profile of individuals with FXS.