Active versus Passive Processing of Biological Motion
IM Thornton, Cambridge Basic Research, Cambridge MA, USA.
RA Rensink, Depts. of Psychology and Computer Science, University of British Columbia, Vancouver BC, Canada.
M Shiffrar, Dept. of Psychology, Rutgers University, Newark NJ, USA.

Perception, 31: 837-853. 2002.   [pdf]


Johansson's point-light walker figures remain one of the most powerful and convincing examples of the role that motion can play in the perception of form (Johansson, 1973; 1975). In the current work, we use a dual-task paradigm to explore the role of attention in the processing of such stimuli. In two experiments we find striking differences in the degree to which direction discrimination performance in point-light walker displays appears to rely on attention. Specifically, we found that performance in displays thought to involve top-down processing, either in time (Experiment 1) or space (Experiment 2), depends to a large extent on the availability of attention. In contrast, performance was disrupted very little by dividing attention in displays thought to favor low-level, local computations. We interpret these results using the active/passive motion distinction introduced by Cavanagh (1991).

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