Discriminating the biological motion of animals

Abstract

Research into biological motion perception has revealed that the human visual system is sensitive to the movement patterns created by both humans and non-human animals when locomoting. In order to further assess the ability of the human visual system to detect the biological motion of animals with different locomotory patterns, observers were required to discriminate between point light displays depicting an animal in motion and point light displays containing dots moving in ways constrained by the properties present in the biological motion displays, but containing no biological motion themselves. Initial results indicated that naA¯ ve subjects could accurately discriminate between the displays containing biological motion and those containing motion of a non-biological nature. In order to assess this effect further, a second experiment was carried out to investigate the ability of naA¯ve observers to discriminate between biological and non-biological point light displays as a) a function of random punctate visual interference density and b) a function of stimulus duration. To allow further investigation into how biological motion information concerning animals might be utilised by the visual system in naturalistic situations, subjects were tested for simple animal phobias in order to assess whether those subjects with a high fear of certain target animals (snakes and spiders, chosen for the sake of general prevalence of fear) would be able to distinguish the target animal from non-biological trials in the presence of a) greater density of noise and b) shorter stimulus duration. Results indicated that noise density had a significant effect on discrimination performance for both groups even at the lowest level.