Kinetic-imagery ability of mentally retarded young adults.

Two kinetic-imagery tasks were administered to mentally retarded young adults. In one task they had to judge whether pairs of symmetric ice-cream cone figures were the same or different. The cone on the left was always upright, while the cone on the right was oriented either 0 degrees, 45 degrees, 90 degrees, 135 degrees, or 180 degrees clockwise from the upright. Only one-half of the subjects successfully passed a criterion pretest in which they were required to discriminate pairs of upright same--different cones. These successful subjects exhibited a linear increase in their reaction time judgments as the angular discrepancy between stimuli increased, presumably evidence that they were using an analogical mental rotation process. Although their performance was very good on this task, however, it was quite poor on the second task, in which they had to imagine the rotation of a three-block array, which apparently involves a more complex transformation. Subjects who failed to cone criterion task were unable to anticipate the outcome of the block array and produced primarily egocentric (simple reproduction) responses.