Abstract
Previously we have found a dominance effect of the ground plane over other environmental surfaces in determining the perceived relative distance of objects in 3-D scenes, and that this dominance effect was mainly due to the characteristics of the ground plane (Bian, Braunstein & Andersen 2006; in press). In the current study, we investigated whether the ground dominance effect varied with age. In Experiment 1, a scene containing a ground, a ceiling and two vertical posts were presented. Optical contact with the ground indicated that one post was closer, whereas optical contact with the ceiling indicated that the other post was closer. The scene was either in its normal orientation or rotated to the side. In Experiment 2, a blue dot was attached to each post with their location varied from bottom to top of the posts. In both experiments, observers judged which of the two objects (posts in Experiment 1 and blue dots in Experiment 2) appeared to be closer. The results indicated that both younger (mean age 21) and older observers (mean age 72) responded consistent with the ground dominance effect. However, the magnitude of the effect was less for older than younger observers. In order to examine if this age difference was due to differences in fixation we repeated Experiment 2 and measured eye movements. The results indicated no significant difference was found on the percentage of duration of fixation on either the ground plane or the ceiling plane between the two age groups. These results suggest a decreased reliance on ground surface information by older observers in the perceptual organization of scenes.
Supported by NIH AG13419-06