A figural aftereffect produced by a phenomenal dichotomy in a uniform contour.

Abstract

If the central processes responsible for figural aftereffects derive exclusively from peripheral events, then the phenomenal status of a contour should not affect the figural aftereffect it produces. If the central processes also modify the consequences of the peripheral events, an alteration of the figural aftereffect might result. 44 college student Ss were tested in a figural aftereffect displacement paradigm in which the inspection figure contained a centrally fixated uniform contour, phenomenally dichotomized into figure and ground halves by a biased center contour. Control conditions for prefixation judgments and for methodological artifacts were included. At better than the .05 level a differential aftereffect was shown to exist. The results were interpreted as indicating the necessity of examining the role played by central processes in contour perception.

A threshold difference produced by a figure-ground dichotomy.

“…In a previous paper Weitzman (1963) demonstrated that the contour of a figural region produces an aftereffect of greater magnitude than that produced by the contour of a ground region. The aftereffect of a stimulus contour is modified in that paradigm by its position in a figureground dichotomy.…”

“…Creedmoor Institute for Psychobiologic Studies, Queens Village, New York A previous finding (Weitzman, 1963) suggested the possibility that division of the perceptual field into figure and ground regions results in a threshold difference between figure and ground contours. To examine this possibility discrimination thresholds for 2 lines were determined, in tachistoscopic presentation, for 29 college student and student nurse Ss.…”