The authors have previously shown that during self-motion in car driving situations, the perception of another car's trajectory relies both on global visual information such as the optical flow field, and on local visual information such as the optical motion of the other car and the relative optical motion of other car with respect to fixed elements in the environment. Here, the authors studies the environmental factors that contribute to perceptual judgements in relation to the observer's perceptual style (visual-field dependence versus visual-field independence). In an experiment, observers were presented with visual scenes corresponding to the curvilinear self-motion of a driver approaching an intersection where another vehicle was arriving perpendicularly. The factors manipulated were the presence or absence of a spatial reference point (road sign near the intersection), environmental complexity ("road" or "spot" scenes), and the degree of field dependence/independence. Nine field-independent (FI) subjects and seven field-dependent (FD) subjects were asked to predict whether the other vehicle would reach the intersection before or after they would. Their responses were analysed. Overall, subjects' judgements were more accurate with road environments and with a road sign, suggesting that the relative motion of the other vehicle with respect to fixed elements in the environment provide additional useful information. FI subjects were significantly more accurate than FD subjects, suggesting that the former are better at picking up relevant dynamic information in a complex environment. (A)
Abstract