The effect of hypnotic ablation of the background on the magnitude of the ponzo perspective illusion

Abstract

In an attempt to develop an objective measure of hypnotic perception, and also to test the stability of the Ponzo perspective illusion, negative hallucinations were hypnotically induced to ablate the radiating lines of the Ponzo configuration. 3 groups of Ss (including 1 group of simulators) were tested across 3 conditions—unhypnotized, hypnotized, and hypnotized with hallucination instructions. Results indicated that the suggested hallucination did not affect susceptibility to the illusion. Results also suggested that certain hypnotically susceptible Ss might be more susceptible to the Ponzo under all experimental conditions than non-susceptible Ss. It was concluded that suggested hallucinations do not affect performance on the Ponzo illusion and that the Ponzo is a very stable illusion and appears to be highly resistant to variations in instructions and experimental set, as induced by hypnosis.