Psychophysical evidence for a shared representational medium for mental images and percepts.

The intuition that imagery is similar to perception has led many psychologists to assume that imaging an object consists of activating some of the same representational structures that are activated during the perception of that object. This assumption was tested by measuring the effects of visual imagery on concurrent visual perception. The experimental task consisted of a two-interval forced-choice detection task (no stimulus identification required) during which the subject imaged a particular stimulus. In Experiment 1, a matching image led to better detection than a nonmatching image. Interactions between imagery and perception imply a common locus of activity, and the content-specific interactions obtained here imply that the common locus consists of representational structures. In Experiment 2, a matching image facilitated perception only when the image and the stimulus were in the same position. This was taken to imply that the shared representational structures occur at an analog level of perceptual representation.