Multi-Modal Heaviness Perception

University Of Cincinnati Main Campus, Cincinnati OH

Investigators

Abstract

Seemingly the most natural way to gauge an object?s heaviness is to pick it up and move or heft it, thereby engaging the sense of touch. However, research has shown that what a person sees, in addition to what a person feels, contributes to the perception of an object?s heaviness. There is something in the way an object appears to move in response to an applied force that is informative about how heavy the object is. Although heaviness perception was one of the first problems investigated by experimental psychologists, no single theory of human perception currently explains how heaviness perception depends on both the sense of touch and on vision. With support from the National Science Foundation, Dr. Kevin Shockley and Dr. Michael Riley will conduct research that aims to develop a unified account of certain visual and haptic (touch) influences on perceived heaviness. The research will test predictions from a model that describes visual and haptic sensitivity to rotational inertia (resistance to rotational acceleration) as the physical basis of multi-modally perceived heaviness. Briefly, as one tries to rotate an object, it resists; it has rotational inertia. Perceived heaviness, in turn, relates to how much rotational acceleration the object demonstrates in response to the applied muscular torque. How might the object?s responsiveness--its rotational acceleration--be known? Can it be known visually, haptically, or both together? To answer this question, the research will employ virtual reality technology, which permits dissociation of the seen motion of a hand-held object from the felt motion. A visual display depicts a ?virtual object? whose movements are coupled to a physical hand-held object, but the way the virtual object responds to an applied muscular force can be manipulated so the object appears to move in disproportion to its actual movement. Preliminary research has revealed that if the object is seen to move more or less than it is felt to move, perceivers experience the object as lighter or heavier, respectively. Additional experiments employing a haptic virtual reality device will test the broader hypothesis that the relation between applied muscular force and the responsiveness of the hand-held object?whether the responsiveness is detected visually, haptically, or multi-modally?underlies heaviness perception. Identifying the physical basis of heaviness perception may have important practical implications for designing safe and ergonomic hand-held tools and tele-robotic interfaces.