Using the free fall of objects under gravity for visual depth estimation

Abstract

We performed an experiment that tested people’s ability to use the free fall of objects under gravity as a scale referent in a two-dimensional display. Subjects were presented with a two-dimensional computer animation of a fountain on a perspectival video background. Both rich and poor stimuli (i.e., fountains spraying many drops of water or only a single drop) were used. The task was to change the magnitude of simulated gravity so as to make the display appear “natural.” Results indicate that subjects reliably matched gravitational acceleration to apparent depth. Accuracy and reliability of the settings were higher for the rich stimuli than the poor stimuli, demonstrating the importance of complex stimuli for the human perceptual system. © 1993, Psychonomic Society, Inc.. All rights reserved.