Abstract
We reported (2005, under review) a ground surface (compared to ceiling surface) advantage in determining perceived layout (a ground dominance effect). Here we report two experiments using a flicker paradigm to examine if change detection is easier for scenes containing a ground surface as compared to a ceiling surface. In Experiment 1 observers fixated a cross and were presented an original scene (containing a ground and a ceiling surface with randomized black-white checkerboard texture) and a modified scene (with the luminance of one block on a surface changed) for 250ms each in a sequence of A, A, A', A'. The two scenes were alternated until subject's detected a change. Control trials with no change were also included. We found that detecting a change on the ground surface was easier than changes on a ceiling surface. In Experiment 2 we examined if this advantage of the ground surface was due to its location in visual field. On each trial only one surface was presented and the surface was either in the lower visual field or in the upper visual field. We found a change on the ground surface easier to detect in the lower visual field but more difficult to detect in the upper visual field. These results, considered in light of recent ground dominance studies, suggest that the ground surface is of primary importance in the perceptual organization of scenes.
Supported by NIH Grant AG13419-06