Abstract
The ability to extract information from the body movements of others is crucial for predicting the behavior of others and survival. Humans can infer the action, emotional state, and gender of others from a set of dots known as point-light biological motion. The present study investigates whether prior knowledge about the action, gender, and emotional state of others affect biological motion perception. To this end, we conducted three experiments with a cued individuation paradigm in which participants were required to detect the spatial location of a biological motion stimulus presented either on the right or the left of a central fixation. On the other side of the screen, a scrambled motion stimulus was displayed, and we recorded response times. Both stimulus types were embedded in noise dots to increase task difficulty. The number of noise dots in each trial was determined using an adaptive procedure (QUEST). Prior to this task, participants were provided with a cue that predicted the type of the biological motion stimulus. The cue was about the action type in Experiment 1 (N=17), the emotional state in Experiment 2 (N=15), and the gender in Experiment 3 (N=15). For each experiment, we had four sessions in which we manipulated the cue validity (neutral, 50%, 75%, 100%). Our ANOVA results showed that biological motion was individuated faster in the congruent trials than the incongruent trials (p<0.01) when the cue validity was high (75%), and the cue was about the action that the biological motion stimulus displayed but not if the cue was related to the gender and emotional state. Taken together, these results suggest that biological motion perception is affected by prior knowledge, although not all types of knowledge are equally informative.