Abstract
Abstract: We used reaching measures to test covariation in distortions of perceived distance, size and shape and the simultaneous effect of haptic feedback on each property. Participants reached to touch the front, back, left or right sides of virtual spherical targets viewed at eye level and at 5 different distances ranging from 50% to 90% of the maximum reach distance. Three different groups of participants were tested using: (1) static or (2) dynamic binocular vision or (3) dynamic monocular vision. Reaches to the 4 locations on a target were used to evaluate perceived distance (centroid), shape (aspect ratio of width/depth) and size (product of width x depth). First, each group performed 5 blocks of reaches to the 20 locations without feedback. Only the virtual targets could be seen. Then, 5 blocks of reaches was performed with visual feedback. After each reach was measured, a virtual stylus was made visible and participants adjusted its position relative to the visible target sphere. The virtual stylus was congruent with an actual stylus held in. Distortions were present in all measures. Shape analysis revealed that distortions in shape were not consistent with distortions in distance, that is, a single continuous transformation on the space did not account for all distortions. Feedback affected distortions of distance, but not shape. We compared performance across visual conditions. Results are consistent with those of Crowell, Todd & Bingham (2000).