Abstract
Across our evolutionary history, detecting potential prey and predators has been a critical aspect of survival. Among the consequences of this evolutionary past, stimuli that resemble animals are preferentially processed; for example, modern humans initiate saccades to, and detect changes more quickly in, pictures of animals over non-animate objects. Animacy is, however, defined by more than just the canonical shapes or forms of animals. Certain types of motion (i.e., biological motion) also signify animacy, and the human visual system may be predisposed to process these types of motion. For example, we can extract surprising amounts of information about walking from just a few points of light. If biological motion is as salient an indicator of animacy as shape or form, can biological motion capture attention? To answer this question, we compared the time to detect targets in objects that were either moving predictably due to collisions with other objects (nonbiological motion) or moving unpredictably with no such collisions (biological motion). All of the experiments used four geometric objects that moved through the display, bouncing into each other or rebounding off the frame in a predictable manner until one object exhibited biological motion. The first two experiments showed that detecting (Exp1a) and identifying (Exp1b) targets were faster in objects exhibiting biological motion. Because previous research has demonstrated that observers rate objects as more animate with greater changes in direction or speed, the basic procedure of the previous experiments was used with the biological motion having three different angles of direction change (Exp2a) or three different changes in speed (Exp2b). Observers again detected targets more quickly in objects that exhibited biological motion, and response times decreased with greater changes in direction or speed. Thus, biological motion, in and of itself, appears to be capable of capturing attention.
Natural Science and Engineering Council of Canada.