METRIC ASPECTS OF MENTAL IMAGES

This research concerns the representation of size and shape in longter m memory at different levels of abstraction Some authors suggested a d istinction between surface characteristics, including size, depending on an observer's point of view (viewer-centered), and abstract charact eristic based only on an object's shape (object-centered). These studi es raise the question of whether size-information is stored in long-te rm memory. This question may be dealt with by considering the topic of cognitive costs; since abstract representation needs more processing, more time is required to store fewer abstract representations than ma ny viewer-level representations. Two hypotheses were put forward: info rmation about size is preserved when an intermediate rime is allowed t o process visual stimuli, whereas it is discarded when a longer time i s available; subjects who have longer time focus on shape, while subje cts who have less time do not. Subjects were assigned to two groups di ffering in the time allowed to learn visual images. Both groups had to recognize previously learned visual mental images. These images were built up by a subtraction task. The testing stimuli were identical to learned ones, of a different size, or of a different shape. Analysis s howed that information about size is not held in long-term memory. As regards shape, results were controversial.