Haptic and visual size judgements in virtual and real environments

in a series of three experiments, participants were asked to match the sizes of spheres presented in the haptic and visual modalities. Stimuli were either real or virtual. Real spheres were sets of ball bearings of various sizes that could be both viewed and touched. Virtual spheres were presented using a Phantom for the haptic presentations or a 4D screen for the visual presentations. Comparing the judgements made within sensory modalities, virtual spheres of a given size were perceived as significantly larger than their real counterparts for vision, but not for haptics. Across modalities, virtual haptic spheres were perceived as significantly larger than their virtual visual counterparts, while there was no significant difference in the judged size of real visual and real haptic spheres. The results have implications for the design of virtual environments where it cannot be assumed that the sizes of objects as depicted by their designers will be perceived in identical fashion across modalities.