Word frequency and the intentional-incidental verbal-discrimination learning of nonretarded and mentally retarded individuals.

MA-matched nonretarded and mentally retarded persons were given a verbal-discrimination learning task and an associative matching task. In the verbal-discrimination learning task, word frequency was manipulated by having one-half of the participants in each IQ group pronounce for 20 trials the words that were later used in the verbal-discrimination learning task (i.e., the high-frequency condition). The remaining participants pronounced words that were not a part of the task (i.e., the low-frequency condition). Based on an implication derived from frequency theory, I predicted that retarded persons would be more adversely affected by the high-frequency condition than would nonretarded persons; however, results indicated that both groups were adversely affected. The associative matching task was used to test the incidental learning hypothesis. Results revealed a significant Intelligence X Frequency interaction, which indicated that the retarded group exhibited an incidental learning deficit but only under the high-frequency condition. A possible explanation for this finding was discussed within the context of depth of processing.