Biological Motion Processing Without Attention
Ian M. Thornton, Cambridge Basic Research, Cambridge MA, USA.
Ronald A. Rensink, Cambridge Basic Research, Cambridge MA, USA.
Maggie Shiffrar, Rutgers University, Newark NJ, USA.

Perception, 28(suppl.):51. [ECVP 1999; Trieste, Italy.]

Biological motion processing has been shown to be robust across both space (Bertenthal & Pinto 1994; Psychological Science, 5, 221-225) and time (Thornton, Pinto, & Shiffrar, 1998, Cognitive Neuropsychology, 15, 535-552). These findings reflect the obvious ecological significance of such stimuli, which can almost certainly recruit routines at both high and low levels of the visual system as particular task demands dictate.

In the current work we manipulated attention as a way of exploring the nature of biological motion processing when a smoothly walking figure was obscured either by a) a random dot mask (simple) or b) a "scrambled walker" mask (complex). Attention was manipulated by superimposing a change detection task directly on top of the walker display. Such change detection tasks require focused attention.

In the baseline condition, where observers ignored the change detection task, direction discrimination was 100% for both types of walker display. However, when attention was given to the change detection task, complex mask performance fell to chance while the simple mask was relatively unaffected (80%+). These results suggest that global processing of biological motion may involve some form of attentional tracking or "active" motion processing (Cavanagh, 1991 Spatial Vision 5 303-309).

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