Touch can change visual slant perception

The visual system uses several signals to deduce the three-dimensional stru cture of the environment, including binocular disparity, texture gradients, shading and motion parallax. Although each of these sources of information is independently insufficient to yield reliable three-dimensional structur e from everyday scenes, the visual system combines them by weighting the av ailable information; altering the weights would therefore change the percei ved structure. We report that haptic feedback (active touch) increases the weight of a consistent surface-slant signal relative to inconsistent signal s. Thus, appearance of a subsequently viewed surface is changed: the surfac e appears slanted in the direction specified by the haptically reinforced s ignal.