Abstract
In order for humans to communicate, it is important to predict the feelings, thoughts, and intentions of other people not just through verbal information but also through movement information. Therefore we must identify what an action of a person is in. Although it appears to be a highly complicated and difficult task, humans can recognize complex movements of an individual even with impoverished motion information. We examined how presentation rates (speeds) affect the detection of biological motion. In a two-alternative forced-choice task, subjects discriminated normal biological motion sequences from scrambled versions. Upright and inverted stimuli were presented in a forward or backward order at various presentation rates. Performance was generally higher in the condition where the stimuli were presented upright in a forward manner than the other conditions. A clear tuning curve for presentation rate was observed only in the upright-forward condition. These results suggest that the perception of natural biological motion takes into account previous experience in observing human actions.
