Abstract
The ability to distinguish animate from inanimate entities arises very early in human development and is fundamental to our understanding of the physical and social worlds. However, two important questions remain unknown: what spatio-temporal properties in the visual stimuli play an essential role in inducing the impression of animacy, and how animacy perception interacts with other visual processes. To address the first question, subjects were asked to provide animacy ratings for moving displays comprised of Gabor disks that varied in terms of spatial frequency (SF), relative orientation, and global movement patterns. Results revealed bandpass tuning curves across these three dimensions. Animacy was highest for elements with intermediate SF (peak at 0.4 cpd), and reduced for low SF’s in which the oriented structure was not evident. Elements changed direction randomly over time as determined by a Gaussian distribution, where standard deviation represented the extent of directional changes. Animacy peaked at intermediate levels of directional change (s.d. = 32 deg). Finally orientation was either co-aligned with the element’s heading direction or offset to varying degrees. Animacy was highest with co-alignment and decreased monotonically with increasing offsets up to 90 deg. Importantly, these results enable the generation of displays that vary substantially in the degree of perceptual animacy, but that are well-matched in terms of local stimulus properties. To address the second question, we conducted a multiple-object-tracking experiment using the stimuli and parameters derived from the previous experiments. We found that tracking performance was impaired for visual elements with high levels of animacy. This effect was primarily due to interference from animate distracters in the background, presumably because they instinctively pulled attention away from the tracked targets. These results illustrate the spatio-temporal tuning of human vision to perceptual animacy and the tracking results indicate a significant influence of animacy on attentional processes.
Meeting abstract presented at VSS 2015