Unilateral and central projection of symmetry varying in spatial orientation

Abstract

Ss made rapid perceptual judgments about tachistoscopically presented line patters. These were symmetrical or asymmetrical, with axis of symmetry appearing in vertical, horizontal, and oblique orientations. The patterns could also be shown centrally or to either the right or left of fixation. Ss pressed a button for YES if the patterns displayed symmetry and another button for NO if the patterns were not symmetrical. Regardless of whether the patterns projected to both or entirely to one visual half-field, a reaction-time (RT) was found to vary uniformly as a function of the orientation of the patterns. Overall RT’s were shortest for vertically oriented patterns, and longest for those shown about the horizontal and oblique axes. This in turn confirmed the salience of left-right symmetry over symmetry appearing in other spatial orientations. The general pattern of results was consistent with the notion that the perception of symmetry is mediated by processes which serve to align the input stimuli into congruence with a stable internal representation of symmetry.