Motion, context and animacy

Polly Tremoulet, J. Feldman

Research output: Contribution to journalArticlepeer-review


Two experiments investigate how the context in which a moving object is observed influences the impression that the object is a living creature. Subjects were shown a series of short (750 msec.) computer-generated displays featuring a white circle moving against a uniformly dark background that contained a white rectangle. The circle moved at constant velocity except for a single point discontinuity. Subjects were asked to rate these displays on a 1-7 scale according to the strength of their impression that the circle was animate. Results replicate earlier work demonstrating that a trajectory featuring a single change in velocity can produce an impression of animacy, and that the strength of this impression increases with increasing amounts of acceleration and direction change (Tremoulet & Feldman, 2000). The results also indicate that the percept of animacy produced by a particular trajectory depends upon the context in which it is observed, even if the context is an extremely Spartan environment (e.g. a stationary rectangle in an otherwise uniformly dark field). In particular, when the rectangle is placed such that the moving dot just reaches it when the dot changes velocity, ("Bounce" and "Skew" conditions) observers do not tend to see the velocity change as intentional, animate motion. This was true regardless of whether the post-contact path is the one that is predicted by Newtonian laws. In contrast, if the dot travels directly toward the rectangle after its velocity changes ("Goal" condition) observers tend to assign high animacy ratings to the dot. This finding suggests that the impression of animacy depends not only on motion factors, such as conservation of energy, but also on a judgment by the observer as to the causes of motion. A moving target is judged to be alive when its motion path and context are consistent with the target's motion being controlled by mental processes.

Original languageEnglish (US)
Pages (from-to)477a
JournalJournal of Vision
Issue number3
StatePublished - Dec 1 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems


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