PERCEPTION OF ANIMACY

Abstract

One of the primary distinctions we make in understanding the world is between social and non-social objects. Social objects are assumed to be animate, to have some controlling intelligence which directs their behavior and to have aims which serve to orient this behavior. Non-social objects are assumed to be inanimate and their actions are assumed to be both undirected and unoriented. The goal of this thesis was to develop a small set of properties which predict when motions will be perceived as those of animate objects whose actions can be described in intentional terms. The properties were based on Newton's Laws of Motion and on Tolman's analysis of intentional action. They focused on the conditions for the initiation of an object's movement and on variations in the object's speed and direction of movement as these relate to obstacles in the field. Simple computer displays were created to assess the validity of the properties. Individual dots moved on a field with or without obstacles in the dot's path. Subjects were asked to judge the degree to which the movement looked as if it were that of an alive, self-moving and purposeful object as opposed to that of a non-alive, physical object. They gave both yes/no judgments and confidence ratings to a series of questions presented following each display. The properties differed in the degree to which they contributed to the impression of animacy. If an object initiated its own movement or avoided impact with a barrier, subjects judged it to be animate. However, changes in velocity or unusual deflections following impact did not contribute to the impression of animacy. Finally, a sustained forward path toward a goal did not contribute to the impression of animacy, although it did contribute to the impression of intentional action. These results show that the most highly informative transformations for the determination of animacy are those which are not sensitive to environmental effects and which show qualitative rather than quantitative changes in the state of the object.