Directed Forgetting in Incidental Learning and Recognition Testing: Support for a Two-Factor Account.

Abstract

Abstract:Instructing people to forget a list of items often leads to better recall of subsequently studied lists (known as the benefits of directed forgetting). The authors have proposed that changes in study strategy are a central cause of the benefits (L. Sahakyan & P. F. Delaney, 2003). The authors address 2 results from the literature that are inconsistent with their strategy-based explanation: (a) the presence of benefits under incidental learning conditions and (b) the absence of benefits in recognition testing. Experiment 1 showed that incidental learning attenuated the benefits compared with intentional learning, as expected if a change of study strategy causes the benefits. Experiment 2 demonstrated benefits using recognition testing, albeit only when longer lists were used. Memory for source in directed forgetting was also explored using multinomial modeling. Results are discussed in terms of a 2-factor account of directed forgetting. Key words: directed forgetting, intentional forgetting, study strategies, multinomial modeling, inhibition Article:When people find out that they are talking to a memory specialist, they often ask about how to improve their memories and how to remember more effectively. The irony of this is that people should perhaps be interested in how to forget things better in order to improve memory, as it appears that forgetting often leads to better memory (R. A. Bjork, 1989).One way to study the linkage between forgetting and learning is to ask people to forget something they have just studied-a procedure known as directed forgetting. A forget instruction can be delivered either after each item (known as the item method) or after a block of items (known as the list method). These two methodologies were shown to have different underlying mechanisms, with the item method reflecting encoding phenomena (better encoding of forget vs. remember items), and the list method most likely reflecting retrieval phenomena (e.g., Basden, Basden, & Gargano, 1993;R. A. Bjork, 1989). The current article focuses on the list method of directed forgetting because the mechanism underlying this phenomenon has created a variety of theoretical viewpoints as opposed to the mechanism supporting the item method. (For a more complete review of directed forgetting and related procedures such as specific intentional forgetting, see H. Johnson, 1994, or MacLeod, 1998 A typical list method directed forgetting study presents participants with two word lists to study. Between administration of the two lists, the experimenter instructs half of the participants to forget the first list and the  We are grateful to Xiangen Hu and William Batchelder for their help with the GPT.EXE software and multinomial models in general. Thanks also go to Kathryn Hughes, Kristin Kukharenko, Ryan Lobo, and Isabel Manzano for their help in data collection and scoring.

Short article: The selective directed forgetting effect: Can people forget only part of a text?

“…Robust costs occur following incidental learning (Geiselman et al, 1983;Sahakyan & Delaney, 2005;Sahakyan, Delaney, & Waldum, 2008), which is difficult to explain from a selective rehearsal perspective as participants are not supposed to rehearse in incidental learning. Additionally, re-presenting a portion of the to-be-forgotten items as a recognition test just before a recall test eliminates the costs for explicitly but not implicitly encoded items (e.g., E. L. Bjork & Bjork, 1996).…”

“…We expected no directed forgetting benefits because benefits usually only emerge when a strategy change leads to differential strategy usage on List 2 across conditions (Sahakyan & Delaney, 2003, 2005. For sentence recall, the majority of our participants informally reported a "deep" encoding strategy of trying to form a story about the characters on both List 1 and List 2.…”

List-method directed forgetting: The forget cue improves both encoding and retrieval of postcue information

“…Recently, however, a number of dissociations between the two effects have been reported. For instance, whereas list 1 forgetting has been found to be present irrespective of encoding style, list 2 enhancement has arisen for intentionally encoded material but not for incidentally encoded items (e.g., Sahakyan & Delaney, 2003;Sahakyan, Delaney & Waldum, 2008b); whereas list 1 forgetting has been reported to be present in recall but to be absent in recognition, list 2 enhancement has arisen in both recall and recognition (e.g., Benjamin, 2006;Sahakyan & Delaney, 2005); regarding electrophysiological brain activities, list 1 forgetting and list 2 enhancement have been found to be related to separate effects in oscillatory brain function (Bäuml, Hanslmayr, Pastötter & Klimesch, 2008).…”

Forgetting is effortful: Evidence from reaction time probes in an item-method directed forgetting task

“…This observation is inconsistent with a common mechanism and has resulted in research that compares item-method tasks with list-method tasks in an effort to discern the mechanism(s) through which R and F instructions operate to influence later memory performance (e.g., Basden, Basden, Coe, Decker, & Crutcher, 1994;Conway f & Fthenaki, 2003;MacLeod, 1999). The culmination of this research suggests that item-method directed forgetting is mediated by selective rehearsal favoring R items (Basden et al, 1993; see also Basden & Basden, 1998), whereas list-method directed forgetting is mediated by the inhibition of F items at the time of retrieval (e.g., Geiselman et n al., 1983) or by a change of mental context between n study and test (e.g., Sahakyan & Delaney, 2005;Sahakyan & Kelley, 2002; for another alternative, see also Sheard & MacLeod, 2005). pression of F words, followed by the focused processing of R words.…”