Weak overcomes strong in sensory integration: Shading warps the disparity field

Human perception is often based on the integration of multiple sensory cues, where more statistically reliable cues are considered to have stronger influence on the percept. For example, in three-dimensional (3D) shape perception, binocular disparity is considered the most reliable cue at close distances, while pictorial cues like shading are considered less reliable. In three within-subject experiments, we instead show that shading can override disparity, a result that cannot be explained by its measured reliability, cue vetoing, nor cue promotion. Observers judged the shape of a disparity surface that was combined with different shading patterns. In all tests, shading altered the perceived shape specified by a strong disparity signal in a way that could not be predicted by standard accounts of 3D perception. We find an example of unaccounted-for cue cooperation, where shading becomes strong when it interacts with disparity., , , # Weak overcomes strong in sensory integration: Shading warps the disparity field Paper:Â [https://doi.org/0.1098/rspb.2024.1758](https://doi.org/0.1098/rspb.2024.1758) Data/Analysis:Â [https://doi.org/10.5061/dryad.zgmsbcckn](https://doi.org/10.5061/dryad.zgmsbcckn) This contains the complete data collected in three within-subject experiments investigating the effect of shading on the perceived depth of local points on stereoscopically presented surfaces. Data from experiments 1 and 2 are collected through the dot placement task, where human observers adjust the disparity of a small dot until it appears to rest on a stereoscopically presented surface in front of them. Units are in millimeters. The third experiment employed a forced-choice variation of the dot placement task, where observers reported whether a temporarily flashed disparity-defined dot appeared to be behind the surface in depth. The comparison levels are in millimeters. Further details are available in the commented anal...