Evidence of atypical processing of biological motion in Autistic Spectrum Disorders

Background: It is known that Autistic Spectrum Disorders (ASDs) are associated with perceptual difficulties, and it has been suggested that the perception of motion and, more specifically, biological motion may be affected. 

Objectives: To determine whether the perception of biological motion is impaired in people with ASDs relative to neuro-typical individuals.

Methods: Exp 1-Using a two-alternative forced choice paradigm we investigated participants’ ability to detect point-light walkers in noise.  A walker containing varying numbers of points was presented to either the left or right of the centre of the screen within a noise mask of varying numbers of dots.  Participants were asked to determine whether the walker was present in the left or right of the display.  Exp 2-To rule out effects of divided attention between each side of the displays in experiment 1 a second task was designed in which participants judged the direction of motion of a centrally presented point light walker within a noise mask.  In one condition the walker preserved varying degrees of structural information within a noise mask containing an opposing motion signal.  In the second condition the walker contained no structural information but was still masked with noise points containing opposing motion signals.

Results: Results from Experiments 1 suggest that participants with ASDs required stronger biological motion signals than neuro-typical participants and that they were more sensitive to masking noise.  Currently results from Experiment 2 with neurotypical participants showed that structural information improves performance at direction discrimination.  From the results of Experiment 1 we predict that the benefits of structure will be diminished among the ASD group.

Conclusions: People with ASDs have difficulties in detecting biological motion given a weak or noisy signal and we predict that the benefits of structural information will be diminished in direction discrimination tasks.