The Contribution Of Monocular And Binocular Depth Cues To Size Discrimination Of 3D Objects

Abstract

The study of perceived size has often been linked to distance, with the role of depth cues, motion and interaction receiving less attention. Here, we evaluated the contribution of depth cues to perceived size during passive viewing and active interaction with 3D shapes in virtual reality. In Experiment 1, observers’ precision was similar in both passive and active conditions, and across modality. In Experiment 2, we increased shape complexity and added an object motion condition to make the task more difficult. Results revealed that precision was high under binocular viewing in both conditions and but significantly reduced in the monocular active condition. Movement data indicated that observers moved laterally to obtain depth from motion parallax in the monocular active condition, but this strategy did not improve precision. These findings underscore the importance of binocular depth information in perceiving 3D object size, even when motion or interaction could theoretically enhance size judgements.