Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6202994 | Vision Research | 2016 | 11 Pages |
â¢Manipulation of surface layout differentially affects perceived size and distance.â¢Change in perceived size is not attributable to change in perceived distance.â¢The differential effect is contrary to the logic of cue combination and mediation.â¢Optical variables for perceived size and distance have different specifications.
The historical but questionable size-distance invariance hypothesis (SDIH) features computation over geometric, oculomotor, and binocular cues and the coupling of percepts-perceived size, Sâ², is mediated by perceived distance, Dâ². A contemporary non-mediational hypothesis holds that Sâ² and Dâ² are specific to distinct optical variables. We report two experiments with an optical tunnel, an arrangement of alternating black and white concentric rings, that allows systematic manipulation of the optic array at a point of observation while controlling a variety of size and depth cues. Participants viewed targets of different sizes at different distances monocularly, reporting Sâ² and Dâ² via magnitude production. In Experiment 1, the target was either placed in a continuous tunnel (extending 164Â cm) or in a tunnel that truncated at the target's location. Experiment 2 included a third tunnel, one that was truncated with a flat depiction of the posterior surface structure that would have been visible in the continuous tunnel. In both experiments, Sâ² decreased with D but Dâ² was unaffected by S. Partial correlation analyses showed that the relationship between Sâ² and Dâ² was not significant when the contributions of other variables were removed. Importantly, Sâ² and Dâ² were affected differently by manipulations of the optical tunnel's continuity while computationally obvious visual cues were controlled. These outcomes suggest that Dâ² is not a mediator of Sâ². Rather Sâ² and Dâ² are independently determined with correlated but different optical bases, results that support the direct model.