Weight perception and the haptic size-weight illusion are functions of the inertia tensor.
The complex effects of mass and volume on weight perception (e.g., the size-weight illusion) were hypothesized to follow simply from invariants of rotational dynamics. In Experiments 1-3, the rotational inertia of wielded, occluded objects was varied independently of mass, size, and torque. Perceived heaviness depended only on rotational intertia. Reanalysis of J. C. Stevens and L. L. Rubin's (1970) study revealed that size's influence on weight perception depends on specific patterns of the eigenvalues of the inertia tensor. These patterns were simulated in Experiments 4-6 with objects of fixed mass, volume, and visible size. Perceived heaviness decreased and increased, respectively, over object sets with the eigenvalue patterns of (a) constant mass, increasing volume and (b) increasing mass, constant volume. Weight perception and the size-weight illusion depend on stimulus invariants, not inference.
Amazeen
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Center for the Ecological Study of Perception and Action, Department of Psychology, University of Connecticut, Storrs 06269-1020, USA. cespal@uconnvm.uconn.edu
Turvey
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D005260:Female; D006801:Humans; D008297:Male; D009903:Optical Illusions; D012399:Rotation; D012858:Size Perception; D014892:Weight Perception