Haptic feedback affects visual perception of surfaces

To derive an estimate of surface slant, the visual system combines information from several cues, each weighted according to its reliability. We asked whether the weights change after providing haptic feedback consistent with one cue only. During the feedback phase of the experiment, subjects pushed a cube across various planes. The cube and the planes were seen and felt. Visually the plane had texture and disparity gradients specifying different slants. Haptic sensations for the cube and plane were provided with a force-feedback device (PHANToM); the haptic feedback for the plane was consistent with its texture gradient only. Before and after the feedback phase, subjects made slant settings (without haptic feedback) from which we determined the weights assigned to texture and disparity. The texture weight increased significantly from 25 to 38. We also conducted two control experiments that showed that the change in weight does not occur over time without the texture - disparity conflict and that the weight change was not caused by visual experience alone. We conclude that giving haptic feedback consistent with one cue causes its weight to increase in a purely visual task. Thus, haptic feedback affects visual surface perception. Calibration of the visual system is affected by visuomotor interaction