The control of working memory resources in intentional forgetting: Evidence from incidental probe word recognition ☆ Jonathan M. Fawcett ⁎, Tracy L. Taylor Dalhousie University, Department of Psychology, Halifax, NS, Canada, B3H 4J1 abstract article info Article history: Received 16 June 2011 Received in revised form 30 September 2011 Accepted 1 October 2011 Available online 26 October 2011 PsycINFO codes: 2100 (General Psychology) 2340 (Cognitive Processes) 2343 (Learning & Memory) Keywords: Intentional forgetting Incidental memory Working memory Cognition We combined an item-method directed forgetting paradigm with a secondary task requiring a response to discriminate the color of probe words presented 1400 ms, 1800 ms or 2600 ms following each study phase memory instruction. The speed to make the color discrimination was used to assess the cognitive demands associated with instantiating Remember (R) and Forget (F) instructions; incidental memory for probe words was used to assess whether instantiating an F instruction also affects items presented in close tempo- ral proximity. Discrimination responses were slower following F than R instructions at the two longest inter- vals. Critically, at the 1800 ms interval, incidental probe word recognition was worse following F than R instructions, particularly when the study word was successfully forgotten (as opposed to unintentionally re- membered). We suggest that intentional forgetting is an active cognitive process associated with establishing control over the contents of working memory. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Forgetting has a poor reputation in the eyes of the public — as exem- plified by the financial success of services promising to eradicate it alto- gether. While this may sound laudable, academics (e.g., James, 1950) have long realized that the inability to suppress an undesired thought or memory may be as troublesome, if not more so, than the inability to maintain a desired thought or memory indefinitely. In the laboratory, intentional forgetting can be studied using an item-method directed for- getting task. Participants are presented with a list of words, one after the other, each followed by an instruction to Remember (R) or Forget (F). During a subsequent memory task in which participants are tested ex- plicitly for all study words, participants typically recall or recognize more R words than F words. This difference is known as a directed for- getting effect (see MacLeod, 1998) and cannot be explained by demand characteristics (MacLeod, 1999). The directed forgetting effect obtained in an item-method paradigm is often explained by selective rehearsal at encoding (e.g., Basden, Basden, & Gargano, 1993). According to this account, maintenance rehearsal refreshes each study word in working memory until the instruction is presented. Following an R instruction, elaborative encoding is engaged to encourage retention; following an F instruction, the word is dropped from the rehearsal set and permitted to decay passively. Because the typical interpretation of the selective rehearsal account fails to describe how F words are eliminated from the rehearsal set, one is led to believe that maintenance rehearsal ceases without any further cognitive pro- cesses acting upon the to-be-forgotten information. This interpretation essentially purports that successful intentional forgetting occurs due to the passive decay of an unrehearsed memory trace. Recent evidence has challenged a passive decay interpretation of forgetting by demonstrating that instantiating an F instruction at encoding is even more cognitively demanding than instantiating an R instruction (Fawcett & Taylor, 2008). Indeed, following an F instruction participants are slower to detect, localize, or discriminate a secondary visual (e.g., Fawcett & Taylor, 2008) or auditory (Fawcett & Taylor, 2009, December) probe; less likely to make false alarms on probe- absent catch trials (Fawcett & Taylor, 2008); and, because of this slowing on F versus R trials, more likely to successfully prevent an unwanted motor response (Fawcett & Taylor, 2010). Moreover, inhibition of return (IOR) – an effect normally revealed following the removal of visuo- spatial attention from a peripheral location – is larger following F than R instructions (e.g., Fawcett & Taylor, 2010; Taylor, 2005; Taylor & Fawcett, 2011). These findings are incompatible with the notion that for- getting occurs due to the passive decay of an unrehearsed memory trace and instead suggest that instantiating an F instruction initiates an active Acta Psychologica 139 (2012) 84–90 ☆ We would like to thank Dr. Aaron Newman, Dr. Ray Klein, Dr. John Christie and Carl Helmick for their contributions. This research was funded by a Discovery Grant to TLT from the Natural Sciences Engineering and Research Council of Canada (NSERC); JMF was supported by an NSERC Canadian Graduate Scholarship and a Killam Predoctoral Scholarship. ⁎ Corresponding author. Tel.: + 1 902 494 3001. E-mail address: jmfawcet@dal.ca (J.M. Fawcett). 0001-6918/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.actpsy.2011.10.001 Contents lists available at SciVerse ScienceDirect Acta Psychologica journal homepage: www.elsevier.com/ locate/actpsy