DYNAMIC SIZE PERCEPTION AS A FUNCTION OF TARGET LOCATION IN EGOCENTRIC SPACE

Two experiments were run in which subjects judged the sizes of stimuli that moved toward and away from them in total darkness by varying a c omparison stimulus. In Experiment 1, the target was centered with resp ect to eye level in the first condition, extended upward from the eye level in the second condition, and extended downward from eye level in the third condition. The subjects were instructed to maintain a level gaze in all conditions. All targets changed in apparent size as a fun ction of varying distance, but the type of change was contingent upon the egocentric location of the stimulus. In Experiment 2, the point at which subjects fixated the stimuli was manipulated. Varying fixation had no effect upon apparent visual size. These data were interpreted a s supporting an egocentric explanation of size perception.