Old/new differences in direct and indirect memory tests using pictures and words in within- and cross-form conditions: Event-related potential and behavioral measures

Indirect measures of repetition priming are more sensitive to changes in surface features than are direct measures of memory. This dissociation may reflect differences in the extent to which the two tasks rely on form-specific processes, or on the activation of different memory systems. To assess this, subjects at study made semantic discriminations to a mixed List of pictures and words. At test, half the concepts were repeated in the surface form presented at study while half were repeated in the other surface form. Subjects in the indirect test continued making the same discrimination, whereas those in the direct test performed a yes/no recognition task. For both tasks, significant old/new within-form differences were found for event-related potential (ERP) and reaction time (RT) measures. Cross-form old/new differences were reliable only for the word-picture condition in the direct task and only for the ERP indices. These data suggest that both direct and indirect memory tasks are influenced by form-specific as well as form-non-specific processing, and that neither the transfer-appropriate processing nor memory systems approaches can completely account for this pattern of results. (C) 1997 Elsevier Science B.V. All rights reserved.