Mirror-Image Discrimination: A Purely Perceptual Measurement with Phi Motion

Abstract

Mirror-image forms were used as phi stimuli in a measurement procedure rendered automatically and compellingly meaningful through the unique contribution of perceptual constancy to the determination of the threshold for phi. Because phi responses are based on unlearned behavior, the pretraining required on conventional tests is eliminated, and a purer measurement of discrimination ability is attained. Using the phi technique, it was found that a group of 12 5-yr.-olds could discriminate like-oriented from mirror-image stimuli as well as did 12 adults.