ON THE LOGIC OF TESTING THE INDEPENDENCE ASSUMPTION IN THE PROCESS-DISSOCIATION PROCEDURE

The process-dissociation procedure is designed to provide quantitative estimates of the influence of explicit and implicit memory in a varie ty of tasks. The procedure relies on the assumption that these two for ms of memory produce independent influences on performance. Prior inve stigators have attempted to test this assumption by determining whethe r the parameter representing the influence of implicit memory (denoted A) is constant across experimental conditions. I argue that the const ancy of A cannot provide an appropriate test of the independence assum ption, because (1) the prediction of constancy can be generated withou t the assumption of independence, obviating the need to posit independ ence; and (2) the constancy of A does not necessarily imply independen ce, even if one assumes that a dependency hypothesis, supplemented by ancillary assumptions (Curran & Hintzman, 1995), pre diets differences in A. I close by emphasizing that we can test the independence assump tion by using standard procedures that compare the fit of a model that assumes independence with the fit of a model that assumes dependence.