High-speed memory-scanning task performance of mildly mentally retarded and nonretarded individuals.

Mildly mentally retarded and CA-matched nonretarded subjects were required to memorize lists of English letters and Chinese characters varying in length from one to four elements. Single probe letters or characters were presented following memorization. The subject responded yes if the probe was a member of the memorized list or no if it was not. Subjects were encouraged to respond quickly but without making errors. Choice reaction times (RTs) were measured from probe onset to the depression of the yes or no response key upon which the index finger of the appropriate hand rested. Retarded subjects demonstrated slower overall choice mean RTs relative to the nonretarded group. Results also suggest that the processing difference lies in the memory scanning as opposed to the encoding/decision/response component of the linear model (Sternberg, 1969); however, this suggestion is limited by the disparity of the group data sets.