The relationship of current manual preference (phenotypic handedness) and family history of handedness (genotypic handedness) to memory for imageable stimuli was studied. The purpose of the study was to test the hypothesis that genotypic handedness was related to lessened cerebral lateralization of Paivio's (1969) dual memory systems. The structure of memory was not at issue, but the mediation of storage and retrieval in memory has been explained with reference to verbal or imaginal processes. Verbal mediation theories and supporting data were reviewed along with imaginal theories and supporting data for these latter theories. Paivio's (1969) dual coding and processing theory was considered a conceptual bridge between the competing positions.