Depth information from binocular disparity and familiar size is combined when reaching towards virtual objects

Reaching movements towards stereoscopically presented virtual objects have been reported to be imprecise. This might be a problem for touch interaction with virtual environments. Estimating the distance to an object in personal space relies on binocular disparity and other depth cues but previous work on the influence of familiar size for reaching and grasping has produced conflicting results. We presented a virtual tennis ball and manipulated binocular disparity as well as the size of the tennis ball. The results suggest that depth information from binocular disparity and from familiar size is combined for reaching movements towards virtual objects. However, subjects differed in the weight they assigned to each depth cue.