The study compared the acquisition, generalization, transfer, and maintenance of language comprehension and production responses by persons at two IQ levels: mentally retarded (N=10) and nonretarded (N=10). The two levels of the IQ Level factor were combined factorially with two levels of a Training Condition factor: Comprehension-Production and Production Only. Participants in the former groups were trained sequentially to (a) comprehend coin labels by pointing and then (b) produce verbally the correct coin label. Participants in the Production Only groups were trained on the latter response only. A three-factor mixed design with one repeated measure plus a multiple baseline across coin responses was employed. Results indicated that both mentally retarded and nonretarded subjects attained a high level of acquisition and maintained their performance on 1- and 4-week follow-up tests. No difference occurred between mentally retarded and nonretarded participants in magnitude of acquisition, but the mentally retarded groups took approximately three times as many trials to complete training. Data also suggested, contrary to past research, that generalization from comprehension to production was bidirectional, with no difference in magnitude between mentally retarded and nonretarded subjects. Transfer from comprehension to production occurred in both nonretarded and retarded subjects; comprehension training facilitated a savings of trials in production training. These results show that language differences between retarded and nonretarded persons are quantitative rather than qualitative as some past research may have suggested.
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