Postural Determinants of Perceived ReachabiIity
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Moving and acting in the environment require a constant monitoring of objects, obstacles, and their location. It is difficult to think of any action that does not require such monitoring which specifies the situation of the perceiver/actor in the environment and helps determine what objects afford for action. Reaching, for example, is an action thattypically requires such monitoring. An object's reachability is detected in reference to the particular situation and characteristics of the perceiver/ actor. Indeed, the detection of objects' affordances is a fundamental feature of perception (Gibson, 1979). The two experiments reported address the general issue of perceiving objects' affordances, and in particular, the determination of perceived reachability in terms of postural constraints, degrees of behavioral freedom, and the engagement of the whole body of the perceiver/actor. Two questions guide these experiments: How is reachability perceived, and what information specifies it?