Abstract
The distance from the observer to an object on the ground plane (egocentric distance) can be recovered from the information about the height of observer’s vantage point and the information about the angular declination of the object (angle subtended by the direction to the horizon and the direction to the object location on the ground plane). Egocentric distances are generally underestimated. It has been suggested that this is due to overestimation of angular declination by a constant factor. With distance held constant, this hypothesis predicts that underestimation will be more pronounced for greater heights of the vantage point. We tested this prediction in two experiments. In Experiment 1 observers judged distances in three conditions: lying on the ground, standing, and standing on a 80 cm high platform. The object whose distance was judged was an experimenter (E1), standing on the ground at 5, 10 and 15 meters from the observer. Observers judged E1’s distance by instructing a second experimenter (E2) to move away or towards E1 in order to make the E1-E2 distance the same as the E1-observer distance. The E1-E2 direction was perpendicular to the E1-observer direction. We replicated the general underestimation of egocentric distances. However, we found no effect of vantage point height. In Experiment 2 observers were either standing on the ground or on a platform. Their task was to match the distance of a small object at their eye height to the distance of another small object lying on the ground, and vice versa. The positions of the objects were manipulated through a system of cords and pulleys, and their to-be-matched distances were 1, 3 and 5 meters. An ANOVA followed by Scheffe tests found no effects of height of vantage point in any condition. Thus we were not able to confirm the angular declination hypothesis.
Meeting abstract presented at VSS 2012