On the Cost and Benefit of Taking it out of Context: Modeling the Inhibition Associated with Directed Forgetting

On the Cost and Benefit of Taking it out of Context: Modeling the Inhibition Associated with Directed Forgetting Kenneth J. Malmberg (malmberg@cas.usf.edu) University of South Florida Department of Psychology, 4202 East Fowler Ave., PCD 4118G Tampa, FL 33620 USA Melissa Lehman (mlehman@mail.usf.edu) University of South Florida Department of Psychology, 4202 East Fowler Ave., PCD 4118G Tampa, FL 33620 USA Lili Sahakyan (l_sahaky@uncg.edu) University of North Carolina Department of Psychology 296 Eberhart Building. PO Box 26170 Greensboro, NC 27402 USA that the to-be-remembered items are better recalled than the to-be-forgotten items. Here we utilize the list method of directed forgetting, although we will discuss the item method in the General Discussion. Traditionally, subjects study two lists of items (L 1 and L 2 ). After studying L 1 , subjects are sometimes told that their memory for L 1 will not be tested. Much to the chagrin of those in the forget condition, subjects are then told at test to recall items from both lists. There are two effects of the “forget” instruction when memory for both lists is subsequently tested via free recall: L 1 items are remembered worse and L 2 items are remembered better in the forget L 1 condition. That is, P(L 1 recall – forget) P(L 2 recall – remember). These effects are referred to as the cost and the benefit of directed forgetting, respectively (Sahakyan & Kelley, 2002). Abstract Forgetting can occur as the result of unconscious or automatic memory processes or as the result of conscious control. The later form of forgetting is often referred to as suppression, repression, or inhibition, and it is investigated in the laboratory using the directed forgetting procedure. The authors describe and empirically test the first formal model of directed forgetting, implemented within the framework of the Search of Association Memory Theory (SAM). The critical assumption is that episodic memory can be suppressed by a conscious attempt to alter the mental context in which new memories are encoded. The present model accounts for both veridical and erroneous free recall performance. Keywords. Memory; Cognitive Models Directed Forgetting Any spouse, partner, graduate student, or even Sigmund Freud would tell you that the notion that people intentionally forget prior events is not new. While Freud posited that the forgetting of negative experiences is a mechanism for alleviating stress or anxiety, some memory theorists have posited that forgetting some experiences is necessary in order to remember other experiences (e.g., Bjork, LeBerge, & Legrand, 1968). How, not why, one intentionally forgets is the subject of this paper. Intentional forgetting is investigated in the laboratory using two directed forgetting methods: the item and the list methods. In the item method, subjects study a list of items, and for each item they are informed if their memory for that item will be later tested. Importantly, memory is tested for all items, regardless of whether they were told during study that the items were to be remembered or not. For instance, memory might be tested using a free recall procedure, whereby subjects are asked to generate as many items from the list as they can in any order. The common finding is Modeling Directed Forgetting There are several traditional explanations of directed forgetting (MacLeod, 1998 for a review). L 1 items might be rehearsed less often following forget instructions. Alternatively, some suggest that the cost and benefit of directed forgetting is due to output interference; L 2 items tend to be recalled before L 1 items, and this creates additional interference when subjects try to recall L 1 items (Geiselman, Bjork, & Fishman, 1983). Presumably, this tendency increases as a result of forget instructions. While differential rehearsal of to-be-remembered and to- be-forgotten items might occur for the item method, it is unlikely to provide a complete explanation of directed forgetting for the list method for reasons that will be made clear momentarily. In addition, it is unclear why L 2 items would tend to be output first to a greater degree after forget instructions than after remember instructions.