Abstract
Does the visual analysis of human movement differ from the visual analysis of non-human animal movement? Since temporal aspects of motion perception are typically investigated using apparent motion displays (Shiffrar & Freyd, 1990, 1993), we presented pictures of locomoting mammals, birds, and humans in a two-frame apparent motion display. In the first condition we presented paired snapshots taken from video footage of locomoting animals. In the second, snapshots were based on video sequences of humans imitating equivalent motions. In a between-subjects design, naïve observers saw either animal or human picture pairs and were asked to make qualitative assessments of the smoothness of the apparent motion they experienced at each of ten different SOAs. Stimulus duration was fixed at 100ms and the interstimulus interval varied between 0 and 600ms. Qualitative assessments were rendered with a 7-point scale in which 0 represented no apparent motion and 7 indicated perfectly smooth motion. The results suggest an impressive degree of similarity in the qualitative nature of animal and human movement perception across large variations in SOA. That is, the temporal window within which apparent motion can be perceived is very similar for animal and human displays. The results for penguin motion and its human imitation were strikingly different, however, from all other animal/human pairs. One possible explanation may be effects related to the unique dynamics of semi-aquatic animal motion: penguin motion may have been especially difficult for humans to imitate, organize and analyze visually. These results are discussed in the context of recent neurophysiological findings suggesting that common mechanisms may underlie the visual analysis of human and animal motion.
Supported by NEI grant R01 EY12300