Identity Matching of Unfamiliar People from Point-Light Biological Motion

Abstract

Point-light displays (PLDs) (Johansson, 1973) present compelling depictions of humans in motion and contain useful information for action (Dittrich, 1993; Kozlowski & Cutting, 1977) and gender perception (Kozlowski & Cutting, 1978). The few studies that have tested person recognition from PLDs provided weak support for biological motion as an identity cue, but only when participants were asked to name the familiar people depicted. Here, we examined the role of biological motion for identification using an identity-matching task (same or different person) for a large number of unfamiliar identities. We tested a broad range of actions, including walking, running, jumping forward, and boxing. Participants (n = 39) matched identities in 120 pairs of PLDs and responded using a 5-point scale (1: sure the same person to 5: sure different people). Subjects viewed PLD pairs of same action (e.g., both walking) and different actions (e.g., walking and boxing). Results showed performance accuracy well above chance in the same-action condition (mean a-ROC = .70, 95% CI [0.68, 0.73], p < 0.0001). In the different-action condition, accuracy was moderate and also greater than chance (mean a-ROC = .59, 95% CI [0.57, 0.62], p < 0.0001). As expected, identity discrimination was more accurate when the pairs performed the same action rather than different actions (p < 0.0001). For same-action trials, the quality of identity information varied with action type (cf., also Loula et al., 2005). Jumping forward yielded the highest a-ROC score (M=.77, SD=.22), followed by walking (M=.70, SD=.09), and running (M=.63, SD=.21). Boxing yielded the lowest a-ROC score (M=.62, SD=.33). In combination with previous work (Cutting & Kozlowski, 1977; Beardsworth & Buckner, 1981; Loula et al., 2005), the current results suggest that biological motion cues not only provide information reliable for discriminating the identity of familiar people, but also for discriminating unfamiliar identities. Meeting abstract presented at VSS 2017