How Weight Affects the Perceived Spacing between the Thumb and Fingers during Grasping

摘要: We know much about mechanisms determining the perceived size and weight of lifted objects, but little how these properties affect body representation (e.g. grasp aperture hand). Without vision, subjects (n = 16) estimated spacing between fingers thumb (perceived aperture) while lifting canisters same width (6.6cm) varied weights (300, 600, 900, 1200 g). Lifts were performed by movement either wrist, elbow or shoulder to examine whether with different muscle groups affects judgement aperture. Results for compared changes in objects sizes (5.2, 6.6, 10 cm) (600 When lifted, decreased 4.8% [2.2 ‒ 7.4] (mean [95% CI]; P < 0.001) from lightest heaviest canister, no matter they lifted. For widths, 42.3% [38.2 46.4] narrowest widest (P 0.001), as expected size-weight illusion. Thus, despite a highly distorted perception based on their size, we conclude that proprioceptive afferents maintain reasonably stable grasping hand over wide range object weights. Given small magnitude this ‘weight-grasp aperture’ illusion, propose brain has access relatively ‘perceptual ruler’ aid manipulation objects.