Journal of Cognitive Neuroscience
Event-related potentials (ERPs) were employed to investigate whether recognition test items are processed differently according to whether they are used to probe memory for previously studied words or pictures. In each of two study-test blocks, subjects encoded a mixed list of words and pictures, and then performed a recognition memory task with words as the test items. In one block, the requirement was to respond positively to test items corresponding to studied words, and to reject both new items and items corresponding to the studied pictures. In the other block, positive responses were made to test items corresponding to pictures, and items corresponding to words were classified along with the new items. ERPs elicited during the test phase by correctly classified new items differed according to whether words or pictures were the sought-for modality. This finding was interpreted as a neural correlate of the different retrieval orientations adopted when searching memory for words versus pictures. Relative to new items, correctly classified items studied in both target modalities elicited robust, positive-going “old/new” effects. When pictures were targets, test items corresponding to studied words also elicited large effects. By contrast, when words were targets, old/ new effects were absent for the items corresponding to studied pictures. These findings were interpreted as evidence that, in some circumstances, adoption of an appropriate retrieval orientation permits retrieval cues to be employed with a high degree of specificity.