Cross-cultural and educational aspects of the Ponzo perspective illusion

Abstract

The magnitude of the Ponzo illusion was determined for two groups of Ugandans, university students and villagers. For the university population, increase in the depth cues in which the illusion was embedded produced an increase in illusion magnitude similar to that observed among students in an American university. For the villagers, however, no illusion was observed for any of the stimulus conditions. Since the environmental ecology of the two groups was similar, the lack of illusion among the villagers cannot be attributed to differential past history of exposure to depth cues. Rather it is hypothesized that responses to two-dimensional stimuli are determined by both depth and flatness cues, and that the responses of the uneducated observers were determined primarily by flatness cues.