Feedback effects on target search and velocity extrapolation by mentally retarded and nonretarded adolescents.

Equal-CA EMR and nonretarded adolescents stylus-tracked an intermittently disappearing rotary pursuit target with no feedback, auditory feedback, and visual feedback. With no feedback both groups demonstrated an approximately equal increase in distance errors during an 18-second period following disappearance of the target. With auditory and visual feedback, the nonretarded group remained closer to the target than with no feedback and closer than the retarded group under all three feedback conditions. Retarded subjects made more distance errors on a static search task requiring the use of auditory or visual feedback to locate a stationary target. Matching subsets of subjects from both groups on the basis of performance during the static search task eliminated differences in tracking performance during feedback. The ability to use feedback during static search predicted the ability to use feedback during rotary pursuit tracking.