Abstract
Perceptual biases in distance and length perception are influenced by the Horizontal-Vertical llusion, angles (Wolfe et al., 2004), and context (Proffitt, 2006). Of interest is the expression of these biases in human movement. In human movement, hand/arm movements provide a spatial context/referent for distance perception. Examined here are hand movement patterns that form angles, traverse different distances, and movement directions going towards or away from the body. Participants viewed two sets of bodies with hand/arm movements and indicated which set moved the greatest distance. Direction of hand movement was evaluated to determine the influence the body context on distance perception. Movement sets were either towards or away from the body, or a mixture of both. Movement distances varied from 0 (equal distances) to 40% differences to evaluate the sensitivity level for detecting differences in human movement distances. Distance perception was influenced by angles up to 180° and horizontal-vertical movements. Movement direction was significantly modulated distance perception. Movement sets where both patterns were towards the body yielded the most accurate judgments. The least accurate judgments included a mixture of movement direction (towards the body vs away from the body, away from the body vs towards the body). A non-linear increase in accuracy was observed as percent movement distances increased. Most notable were the selective influence of movement angles, direction, and percent difference on distance perception. In sum, direction and pattern of movement modulates distance perception. The body's contextual information reduced distance perception errors when the two sets of movements were matched for direction.