The role of experience in the perception of biological motion

Can the daily work experience of adults translate into differences in the organization of perceptual events? Human observers are especially sensitive to human motion, as opposed to the motion of objects or animals (Shiffrar, 2001). Tests of this sensitivity frequently make use of point-light displays where an image is reduced to a set of points corresponding to key joints such as the shoulders, wrists, hips, knees and ankles (Johansson, 1973). To what degree might experience influence our ability to detect these events? We investigated the potential effect of work experience on the perception of biological motion. Two experiments contrasted the performance of naïve observers, seal trainers and dog trainers. In the first experiment observers were shown canonical and inverted displays based on the motion of seals, dogs and people and asked to report what they saw. Patterns of recognition were compared for each of the experimental groups. A second experiment assessed sensitivity by means of a two-alternative forced choice task. Expert and novice observers were shown canonical and inverted target displays similar to those used in the first experiment and asked to determine the presence or absence of figures embedded in noise. Conditions were blocked by stimulus type and orientation. In Experiment 1 all groups had a tendency to report seeing human motion when viewing canonical displays. In Experiment 2 no differences in sensitivity were found between trainer groups. Familiarity with the actual animals and situations from which point-light displays were abstracted did not directly translate into improved recognition or detection. The relationship between experience and recognition appears to be complex: motor experience may impact visual recognition differently than visual experience. Results are discussed within the context of Gibsonian and perception/action theories that have been advanced to account for our sensitivity to human displays.