Concurrent Processing of Optic Flow and Biological Motion

Abstract

© 2019 American Psychological Association.

The concurrent processing of optic flow and biological motion is crucial for navigating to a destination without colliding with others. Neuroimaging studies and formal models have provided evidence for distinct neural mechanisms involved in processing the 2 types of motion. It may, therefore, be possible to process both types of motions independently. To test for possible interferences at the behavioral level, we conducted a dual task paradigm in which we presented a point-light walker in a flow field that simulated forward motion. Observers judged both the articulation of the walker and the heading direction. We found that varying the difficulty of one task had no effect on the performance of the other task, arguing against interferences. Performance in the biological motion task was similar in dual and single task conditions. For the heading task, concurrence costs were observed when the heading task was difficult but not when it was easy. Concurrence costs did not depend on practice effects, effects of specific motor responses, and incidental processing of biological motion. In line with neuroimaging studies and formal models, our results argue not only for independent processing of optic flow and biological motion but also for concurrence costs affecting heading performance.