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Unaffected perceptual thresholds for biological and non-biological form-from-motion perception in autism spectrum conditions - PubMed

  • ️Fri Jan 01 2010

Unaffected perceptual thresholds for biological and non-biological form-from-motion perception in autism spectrum conditions

Ayse Pinar Saygin et al. PLoS One. 2010.

Abstract

Background: Perception of biological motion is linked to the action perception system in the human brain, abnormalities within which have been suggested to underlie impairments in social domains observed in autism spectrum conditions (ASC). However, the literature on biological motion perception in ASC is heterogeneous and it is unclear whether deficits are specific to biological motion, or might generalize to form-from-motion perception.

Methodology and principal findings: We compared psychophysical thresholds for both biological and non-biological form-from-motion perception in adults with ASC and controls. Participants viewed point-light displays depicting a walking person (Biological Motion), a translating rectangle (Structured Object) or a translating unfamiliar shape (Unstructured Object). The figures were embedded in noise dots that moved similarly and the task was to determine direction of movement. The number of noise dots varied on each trial and perceptual thresholds were estimated adaptively. We found no evidence for an impairment in biological or non-biological object motion perception in individuals with ASC. Perceptual thresholds in the three conditions were almost identical between the ASC and control groups.

Discussion and conclusions: Impairments in biological motion and non-biological form-from-motion perception are not across the board in ASC, and are only found for some stimuli and tasks. We discuss our results in relation to other findings in the literature, the heterogeneity of which likely relates to the different tasks performed. It appears that individuals with ASC are unaffected in perceptual processing of form-from-motion, but may exhibit impairments in higher order judgments such as emotion processing. It is important to identify more specifically which processes of motion perception are impacted in ASC before a link can be made between perceptual deficits and the higher-level features of the disorder.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Selected frames depicting stimuli from the three conditions (BM, SO, and UO).

Stimuli were point light animations composed of 12 white dots presented against a black background. In the Biological Motion (BM) condition, the stimulus was a point-light walker. In the Structured Object (SO) condition, the stimulus was a rectangle composed of point-lights. In the Unstructured Object (UO) condition, the stimulus was a single frame from the walker animation, inverted.

Figure 2
Figure 2. Experimental results.

There was a main effect of Condition but no main effect of Group and no Group by Condition interaction. Noise threshold (NT) was higher in the Structured Object (SO) condition compared with the Biological Motion (BM) and Unstructured Object (UO) conditions, and higher in the BM condition compared with the UO condition. There was no difference between individuals with Autism Spectrum Conditions (ASC) and Normal Controls (NC).

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