The effects of framing ratio and oblique length on Ponzo illusion magnitude

Abstract

The effects of the length of the oblique lines and the distance between the test line and the obliques (expressed as framing ratio) on Ponzo illusion magnitude were assessed. The purpose of the study was to test depth-processing (Gillam, 1973; Gregory, 1970) and pool-and-store (Girgus & Coren, 1982) models of the Ponzo illusion. The data indicated that both oblique length and framing ratio affected illusion magnitude. This result did not provide unequivocal support for either the depth-processing models or the pool-and-store model. A recent revision of assimilation theory (Pressey & Wilson, 1980) is proposed to describe the effects of both oblique length and framing ratio. © 1987 Psychonomic Society, Inc.