Using educable mental retardates (middle school pupils), it was examined whether coding from visual modality to auditory modality or in the reversed direction between stimulus acceptance and response has a facilitating effect on recognition and learning. 1. In the experiment 1, recognition performances (correct responses) were compared between the like modality group (task A. visual memorization-visual recognition; task B. auditory memorization-auditory recognition) and the cross modality group (task C. visual memorization-auditory recognition; task D. auditory memorization-visual recognition). As a result, the cross modality group (the coding condition) was superior to the like modality group. 2. And then, the recognition performances were compared between the two tasks of each group. There was no difference between the tasks (A and B) of the like modality group in recognizing learning words. However, the performances of the visual memorization task (C) in the cross modality group are higher than the auditory (D). This primacy of the visual memorization over the auditory one was observed in paired-associate learning (experiment II) as well. 3. In experiment II, learning performances (correct responses) in paired-associate learning were compared among the visual learning group (the like modality condition), auditory learning group (the like modality condition) and visual-auditory learning group (the cross modality condition). The visual-auditory learning group and visual learning group were at an equal level, and the auditory learning group was at the lowest in the performances. 4. From the outcomes of the experiments mentioned above, the facilitating effect of coding on recognition was confirmed. This effect was considered to be not only due to the verbalization of stimuli by the subjects themselves, but also due to the interruption of intruding of extraneous stimuli into learning stimuli. Further, the primacy of the visual memorization over the auditory one was explained as an effect of the developmental exchange for a way of memorization, and as an effect of utilizing visual cues of stimuli.