Abstract
Individuals' identities can be determined from point-light displays of their actions (Cutting, 1977). Interestingly, observers demonstrate the greatest visual sensitivity to their own movements (Loula, Prasad, & Shiffrar, 2005). Does enhanced visual sensitivity to self-produced motion reflect a lifetime of experience observing one's own limbs move? If so, then visual sensitivity to actor identity should be viewpoint dependent. To test this hypothesis, naïve participants viewed point-light movies of themselves, friends, and strangers performing various actions. Viewpoint varied across condition. Actors were matched for gender, age, and body size so that these cues could not be used for actor identification. Each trial consisted of two different sequentially presented point-light movies of actors performing two different actions. Participants performed a 2AFC identity discrimination task and reported whether each trial showed the same actor or two different actors. In Experiment 1, head mounted cameras were used to create head-centered, axial displays of the point-light actors. In Experiment 2, front and rear views of the point-light actors were created. Consistent with Bulthoff et al (1997), performance was uniformly poor with axial depictions since these point-light displays are difficult to organize. This finding is interesting because observers have extensive visual experience with the head-centered, axial perspective on their own body. Yet, this experience was not reflected with a performance increment. In Experiment 2, identity discrimination performance with self-motion was superior to that with friend and stranger motion across both the front and back views. Since observers have substantially more experience viewing the front, as compared to the back, of their own bodies, these findings suggest that identity discrimination is not defined by view specific experience.
Acknowledgement: Supported by NIH EY12300