Contour symmetry detection: the influence of axis orientation and number of objects

Participants discriminated symmetrical from random contours connected by st raight lines to form part of one- or two-objects. In experiment one, symmet rical contours were translated or reflected and presented at vertical, hori zontal, and oblique axis orientations with orientation constant within bloc ks. Translated two-object contours were detected more easily than one, repl icating a "lock-and-key" effect obtained previously for vertical orientatio ns only [M. Bertamini, J.D, Friedenberg, M. Kubovy, Acta Psychologica, 95 ( 1997) 119-140]. A second experiment extended these results to a wider varie ty of axis orientations under mixed block conditions. The pattern of perfor mance for translation and reflection at different orientations corresponded in both experiments, suggesting that orientation is processed similarly in the detection of these symmetries. (C) 2000 Elsevier Science B.V. All righ ts reserved. PsycINFO classification. 2323; 2346.