Abstract
Two experiments were conducted investigating retroactive inhibition in free recall as a function of rated imagery level (high or low). In Exp. I there was significant retroactive inhibition in all experimental conditions relative to single-list controls and more interference when two lists of the same imagery level were learned than when the lists were different in imagery. In Exp. II all subjects learned a mixed List 1 containing nouns, half of high and half of low imagery. List 2 were nouns of high, mixed, or low imagery. The effect of type of List 2 was not significant, but the interaction of List 1 imagery and type of List 2 did reach significance. The amount of retroactive inhibition-at each level of imagery was related to the number of List 2 words at the same level. Thus, the similarity effect is not dependent on the similarity of Lists 1 and 2 as wholes, as the response-set interpretation of retroactive inhibition suggests, but seems to be due to more specific interference among items similar in imagery.