Previous studies have found a deficit in biological motion perception in participants with autism spectrum condition (ASC). However, the literature is mixed and other studies have found no difference between participants with ASC and controls in the perception of biological motion.
We used a novel paradigm to compare psychophysical thresholds for biological and non-biological motion detection in adult participants with ASC and age-, gender- and IQ-matched control participants.
Participants watched pairs of animations that showed a biological object (a hand) or a non-biological object (a tennis ball) moving across the screen. The velocity profile of the movement was either 100% natural motion (minimum jerk (MJ) for the hand and gravitational (G) for the ball) or 100% constant velocity, or some linear combination of the two extremes. On each trial, two animations were shown successively and participants were asked to judge which was ‘less natural’. A forced-choice adaptive staircase paradigm was employed to generate separate thresholds for the biological and the non-biological conditions. A low threshold indicates a high sensitivity to perturbations to the natural motion velocity profile.
There was a significant interaction between group and condition. This was driven by lower discrimination thresholds in the MJ condition than in the G condition for the control group only. There was no difference in the discrimination thresholds of the two conditions for the ASC group.
Thresholds in the MJ condition were lower than in the G condition for the control group whereas there was no difference between the thresholds in the two conditions for the ASC group. Thus, unlike the controls, the ASC group did not show an increased sensitivity for perturbation to biological over non-biological velocity profiles.
See more of: Sensory Systems, Motor Systems, and Reptetative Behavior
See more of: Autism Symptoms