Size scaling in visual pattern recognition.

Human visual recognition on the basis of shape but regardless of size was investigated by reaction time methods. For successive matching of random figures, reaction time increased linearly with the linear size ratio of stimulus pairs. For single-character classification, reaction time increased with divergence between cued size format and stimulus format such that for character nonrepetitions, the increment in latency was approximately proportional to the logarithm of the linear size ratio of.the two formats. However, when reactions to character repetitions were faster than those to nonrepetitions, the repetition reaction time function was similar to that for successive matching of random figures. The results suggested two processes of size scaling: mentalimage transformation and perceptual-scale transformation. Image transformation accounted for matching performance based on visual short-term memory, whereas scale transformation accounted for size invariance in recognition based on comparison against visual representations in long-term memory. Our visual capacity to classify objects on the basis of shape but regardless of size constitutes a fundamental problem of visual perception. The capacity is expressed when two objects of different sizes are perceived as identically shaped, or equally, when a single object of a specific shape is perceived as a member of a given category regardless of the specific size of the object. The theoretical possibilities in accounting for these