Figure 1.
Coherent motion perception display.
The coherent motion display contains a set of moving dots, a fixed proportion of which are moving in a coherent direction (e.g. 0° in the figure above, in gold), while the rest are randomly replotted. When this proportion (“coherence level”) is high, task difficulty is low.
Table 1.
Psychometric Data.
Figure 2.
One trial of the motion coherence task.
Participants manually indicated the “general direction of motion” of 150 white dots in a central aperture above a fixation point. Viewing duration varied between blocks (200 ms–1500 ms), but the decision period remained constant regardless of viewing duration.
Figure 3.
Coherent motion perception deficit in ASC as viewing duration is limited.
Group coherent motion perception thresholds (+/−1 SE) are shown here. Coherent motion perception thresholds are significantly elevated in ASC at the 200 ms viewing duration. Longer viewing durations restore coherent motion perception, pointing towards atypical accumulation of motion signals in ASC.
Figure 4.
Performance across levels of coherence is offset in ASC at short viewing durations.
Average percent correct at each coherence level (+/−1 standard error) is plotted along side a Weibull curve that is fit to group average performance (for illustrative purposes) for the three viewing durations. Dashed lines mark each group's 82% correct coherent motion perception thresholds. At short viewing durations, the ASC group produces significantly accurate responses across coherence levels.
Figure 5.
Coherent motion perception deficits correlate with measures of autistic symptom severity.
A correlation was found between individual coherent motion perception thresholds at the shortest viewing duration and autistic symptoms, as measured by individuals' total scores on the Autism Diagnostic Observation Schedule (ADOS).