Hemispheric differences in mnemonic processing: the effects of left hemisphere interpretation.

Several studies suggest that the abilities to make inferences and interpret events are stronger in the left hemisphere than the right hemisphere (Gazzaniga, M. S., The Social Brain. Basic Books, New York, 1985). Given that inference and interpretation are important aspects of normal memory functioning (Bartlett, F. C., Remembering: A Study in Experimental and Social Psychology, Cambridge University Press, 1932), one would expect this hemispheric difference to extend to mnemonic processing. Two split brain subjects were shown a series of pictures representing a common scene. Their memory for these pictures was later tested with a lateralized Yes-No recognition test where the distractor pictures were either consistent or inconsistent with the scene. The left hemisphere performed below chance on consistent distractor pictures whereas the right hemisphere was above chance on these pictures and performed at the same level of accuracy as the pictures originally presented. These results suggest that recognition performance in the left hemisphere was more strongly influenced by the expectations for actions common to a scene than the right hemisphere and provide evidence that the left hemisphere superiority in interpretation and inference effect memory performance.