Searching for Mood Dependent Memory

Though it has sometimes been shown that events encoded in a certain state of affect or mood are most retrievable in that state, neither the circumstances under which mood dependent memory (MDM) occurs nor the mechanisms that enable its emergence are as yet well understood. The purpose of the research reviewed here is to clarify these circumstances and mechanisms. To this end, the research focuses on four factors that appear to play pivotal roles in the occurrence of MDM. These factors are (a) the nature of the target events or the manner in which they are encoded (i.e., are events generated through internal mental processes such as reasoning, imagination, or thought more apt to be forgotten following a shift in mood state than are events that emanate mainly from external sources?), (b) the nature of the retrieval task (is it possible to demonstrate mood dependence using implicit rather than explicit measures of memory?), (c) efficacy of mood modification (do strong, stable, and authentic affective states promote the appearance of MDM?), and (d) whether alterations in affect are one-dimensional or two-dimensional (does a shift along both the pleasure and the arousal dimensions of mood impair memory more than does a shift along the pleasure dimension alone?). Exploring these four factors in detail may make it possible to resolve much of the controversy that now surrounds MDM, and to acquire fresh insights into its cognitive and affective foundations.