Directed-Forgetting in Working Memory

How does the intent to remember or forget information affect working memory (WM)? To explore this question, in four experiments, we gauged the availability of the to-be-forgotten information directly. Participants remembered six words presented sequentially in separate frames. After each word offset, the frame turned either blue or orange, indicating a to-be-remembered or to-be-forgotten word, respectively. In all experiments, consistently poor recognition performance for to-be-forgotten words and facilitation of to-be-remembered words demonstrated that intent has a strong impact on WM. These directed-forgetting effects are remarkably robust: They can be observed when testing the to-be-forgotten words up to four times (Experiment 1, n=341), for both item and binding memory (Experiment 3, n=124), and even when information has to be maintained in WM up to 5s until the memory cue is presented (Experiment 2+4, n=302+321). Our study establishes a new method to jointly study the effects of intent on WM content for both relevant and irrelevant information and provides evidence for directed-forgetting in WM. Our research suggests that a combination of two processes cause directed-forgetting in WM: One process reduces memory strength of earlier memory representations as a function of subsequently encoded events. Another process rapidly encodes or boosts memory strength only when the person intends to remember that information.

List-method directed forgetting: Do critical findings generalize from short to long retention intervals?

People can purposefully forget information that has become irrelevant, as is demonstrated in list-method directed forgetting (LMDF). In this task, participants are cued to intentionally forget an already studied list (list 1) before encoding a second list (list 2); this induces forgetting of the first-list items. Most research on LMDF has been conducted with short retention intervals, but very recent studies indicate that such directed forgetting can be lasting. We examined in two experiments whether core findings in the LMDF literature generalize from short to long retention intervals. The focus of Experiment 1 was on the previous finding that, with short retention interval, list-2 encoding is necessary for list-1 forgetting to arise. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to a longer delay of 20 min. The focus of Experiment 1 was on the absence of list-1 forgetting in item recognition, previously observed after short retention interval. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to longer delays of 20 min and 24 h. Implications of the results for theoretical explanations of LMDF are discussed.