We used a visual illusion called motion repulsion as a model system for investigating competition between two
mental representations. Subjects were asked to remember two random-dot-motion displays presented in sequence
and then to report the motion directions for each. Remembered motion directions were shifted away from the actual
motion directions, an effect similar to the motion repulsion observed during perception. More important, the item
retrieved second showed greater repulsion than the item retrieved first. This suggests that earlier retrieval exerted
greater inhibition on the other item being held in short-term memory. This retrieval-induced motion repulsion
could be explained neither by reduced cognitive resources for maintaining short-term memory nor by continued
inhibition between short-term memory representations. These results indicate that retrieval of memory representations
inhibits other representations in short-term memory. We discuss mechanisms of retrieval-induced inhibition and their
implications for the structure of memory.