PICTORIAL AND MOTION-BASED DEPTH INFORMATION DURING ACTIVE CONTROL OFSELF-MOTION - SIZE ARRIVAL EFFECTS ON COLLISION-AVOIDANCE

With computer simulations of self-motion, Ss controlled their altitude as they approached a floating object and, after getting as close as p ossible to the object, tried to ''jump'' over it without collision. Ss jumped significantly later for small objects, compared with larger ob jects that were approached from equal distances at equal speeds and we re positioned at equal clearance heights. This occurred even when accr etion-deletion information was present and when object width and lengt h were varied independently. Results were consistent with studies in w hich Ss judged a large far approaching object to hit the viewpoint bef ore a small near object that would have arrived sooner (P. R. DeLucia, 1991a, 1991b). Results suggest that pictorial information such as rel ative size contributes to active collision-avoidance tasks and must be considered in models of perceived distance and time-to-arrival.