Integration of visual and tactile information in reproduction of traveled distance

Abstract

In the natural world, self-motion always stimulates several different sensory modalities. Here we investigated the interplay between a visual optic flow stimulus simulating self-motion and a tactile stimulus (air flow resulting from self-motion) while human observers were engaged in a distance reproduction task. We found that adding congruent tactile information (i.e., speed of the air flow and speed of visual motion are directly proportional) to the visual information significantly improves the precision of the actively reproduced distances. This improvement, however, was smaller than predicted for an optimal integration of visual and tactile information. In contrast, incongruent tactile information (i.e., speed of the air flow and speed of visual motion are inversely proportional) did not improve subjects’ precision indicating that incongruent tactile information and visual information were not integrated. One possible interpretation of the results is a link to properties of neurons in the ventral intraparietal area that have been shown to have spatially and action congruent receptive fields for visual and tactile stimuli.