| Abstract: | Subjects from Grades 3, 4, 6, and college judged whether pairs of stimuli were identical or mirror-image reversals. One stimulus of a pair was presented upright; the other was rotated 0 to 150° from the standard. The pairs were either alphanumeric symbols or unfamiliar, letter-like characters of the type found on the PMA Spatial Ability Test. Response latencies were measured. The primary results were that (a) the speed of mental rotation increased with development, (b) unfamiliar characters were rotated more slowly than alphanumeric characters, by approximately the same amount at each grade, and (c) unfamiliar characters were encoded and compared more slowly than alphanumeric symbols, by an amount that declined with development. The results are discussed in terms of the component processes that underlie developmental change and individual variation in mental rotation skill. |
