UPDATING AN OBJECTS ORIENTATION AND LOCATION DURING NONVISUAL NAVIGATION - A COMPARISON BETWEEN 2 PROCESSING MODES

In the present study, we compared the effects of two processing modes on the updating of the location and orientation of a previously viewed object in space during a guided walk without vision. In Experiment 1, in order to measure the error for initial perception of object's orie ntation, 12 subjects rotated a miniature model until it matched the me morized orientation of its counterpart object in space. In Experiment 2, they attempted either to keep track of the object continuously (in the object-centered [OC] task) or to estimate the object's perspective only at the terminal vantage point given the trajectory they walked ( in the trajectory-centered [TC] task). Subjects indicated the location of the object by facing it, and then rotated the model in order to in dicate its orientation from the new vantage point. Results showed that , with respect to the TC mode, the OC mode induced a slowdown of the s ubjects' self-paced locomotion velocity for both linear and angular mo vements, and a decrease of the latencies as well as smaller absolute e rrors for the orientation-of-the-object response. Mean signed errors o n object's orientation were equivalent for both processing modes, sugg esting that the latter induced different allocations of processing res ources on a common representation of space updated by ''path integrati on.''