ASA 124th Meeting New Orleans 1992 October

4pPPb5. Haptic illusions in human perception of ``virtual objects.''

Neville Hogan

Depts. of Mech. Eng. and Brain and Cognitive Sci., MIT, Cambridge, MA 02139

Ernest D. Fasse

MIT, Cambridge, MA 02139

Humans are subject to haptic illusions (distortions of their haptic perception of object properties such as length, force, or stiffness) just as they are subject to visual illusions. Understanding haptic illusions is particularly important for implementation and use of virtual environment technologies. Haptic illusions may also reveal fundamental properties of spatio-motor processing in the brain, in particular the geometric foundations of haptic perception and its relation to movement production. If a consistent Riemannian metric underlies biological representations of object geometry, there is a precise mathematical relation between the distortion of the different object features (e.g., length, force, stiffness). Experiments measuring human psychophysical functions for discriminating features of ``virtual objects'' (lengths of sides, angles of corners, stiffnesses, forces) will be reviewed. They show that no single consistent metric underlies this sensory-motor behavior. A distorted perception of the environment would be expected to influence motor behavior. Further experiments will be reviewed which show that certain errors in human movement production can be explained by perceptual distortion. Implications for virtual environment and teleoperation systems will be discussed. [Work supported by NIH and the Fairchild Foundation.]