Abstract
The currency of visual experience consists not only of features such as color and shape, but also higher-level properties such as animacy. We explored one cue that appears to automatically trigger the perception of animacy in an especially powerful manner: directionality, wherein an object (1) appears to have a particular orientation based on its shape (as a wolf's head tells you which way it is facing), and (2) varies this heading systematically with respect to the environment (as a wolf consistently faces its prey during a hunt). Previous studies of perceived animacy have relied on problematic perceptual reports, but we used several new performance measures to demonstrate the power of directionality in some surprising new ways. In all experiments, subjects viewed oriented ‘darts’ that appeared to face in particular directions as they moved. First, in the Don't-Get-Caught! task, subjects controlled the trajectory of a ‘sheep’ on the screen to avoid getting caught by a ‘wolf‘ dart that pursued them. Subjects escaped much more readily when the darts (including the wolf) consistently faced ‘ahead’ as they moved. Second, in the Search-For-Chasing task, subjects had to detect the presence of a chase between two darts. Performance suffered dramatically when all darts (including the wolf) acted as a ‘wolfpack’ — consistently all pointing toward the same irrelevant object. The shapes coordinated orientations masked actual chasing, while simultaneously making each object seem to ‘stalk’ the irrelevant object. Third, in the Leave-Me-Alone! task, subjects had to avoid touching darts that moved on random trajectories, and tended to steer clear of display regions where the darts were oriented as a ‘wolfpack’ facing the subject's shape — demonstrating that subjects find such behavior to be aversive. These results demonstrate a new cue to perceived animacy, and show how it can be measured with rigor using new paradigms.