The plasticity of near space: Evidence for contraction

摘要

The distinction between near space and the space farther away has been well established,as has the relation of this distinction to arm length. Recent studies provide evidence for theplasticity of near space, showing that it is possible to expand its extent ("size") throughtool-use. In the present study, we examine the converse effect, whether contraction of nearspace results from increasing the effort involved on a line bisection task. Adult participantsbisected lines at different distances, while, in some cases, wearing weights. In Experiment1, the arms, specifically, were weighted (wrist weights), and in Experiment 2, more generalbody weights were used (heavy backpack). As in previous studies, unencumbered partici-pants showed leftward bias when bisecting lines at the closest distances and a rightwardshift in bias with increasingly farther distances. With wrist weights, but not a heavy back-pack, participants showed more rightward bias at the closest distances, and a more gradualrightward shift with increasing distance, as if the nearest locations were represented asbeing farther away. These results suggest that increased effort, when specifically relatedto the arm, can serve to reduce the size of near space, providing support for the generallysymmetrical plasticity of near space representations.