Metric aspects of mental images

This research concerns the representation of size and shape in long-term memory at different levels of abstraction. Some authors suggested a distinction between surface characteristics, including size, depending on an observer's point of view (viewer-centered), and abstract characteristic based only on an object's shape (object-centered). These studies raise the question of whether size-information is stored in long-term 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 many viewer-level representations. Two hypotheses were put forward: information about size is preserved when an intermediate time is allowed to process visual stimuli, whereas it is discarded when a longer time is available; subjects who have longer time focus on shape, while subjects who have less time do not. Subjects were assigned to two groups differing 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 showed that information about size is not held in long-term memory. As regards shape, results were controversial.