Trajectory forms as information for visual event recognition: 3-D perspectives on path shape and speed profile.

Trajectory forms in events consist of the path shape and the speed profile (Bingham, 1987, 1995). Wickelgren and Bingham (2004) showed that adults can use the speed profile as visual information to recognize events from different perspectives, despite perspective distortions and differences in optical components. We now investigate whether adults can use trajectory forms to recognize events when the forms are viewed from 3-D perspectives and the path shape and speed profile vary. In Experiment 1, we tested recognition of events that differ in path shape (with the speed profile held constant). In Experiment 2, we tested recognition of events in which speed profiles were mapped onto circular paths. In Experiment 3, as a strong test of sensitivity to trajectory forms, we tested simultaneous separate recognition of speed profile and path shape when both varied across events. In all three experiments, events were viewed from multiple 3-D perspectives. The results show that both the shape of the path and the speed profile provide information for visual event recognition. We found that adults exhibit constancy (or view invariance) in being able to use trajectory forms to identify the same events when viewed from different 3-D perspectives.