Exploring Intentional Forgetting: Using novel Think/No-think paradigms to investigate memory suppression

Abstract

Individual differences in thought suppression are explored in three separate, but related, research efforts. A survey study generated novel insight into the relationship between personality traits and personal beliefs regarding thought suppression, and four separate novel Think/No-think paradigms were used to explore relationships between laboratory measures of memory suppression and personality traits. The survey study utilized a novel inventory, the Retrospective-Prospective Suppression Inventory, to determine individual beliefs regarding use of thought suppression in everyday life. Personality traits that have been implicated in the efficacy of laboratory thought suppression were measured and compared between participants who varied in selfreported thought suppression tendencies and efficacy. Individuals who reported engaging in successful suppression in everyday life were less neurotic, ruminative, and experienced fewer intrusive thoughts than individuals who reported unsuccessful suppressive attempts. The findings suggests that the high-ends of the neuroticism and intrusive thought spectra are occupied by individuals who unsuccessfully attempt everyday suppression, while successful suppressors differ minimally from individuals who report avoiding suppression in everyday life. In two experiments memory for contextual information associated with items that were rehearsed or suppressed was examined, using two novel paradigms. Experiment 1 found participants generally unable to suppress items situated within a matrix of 9 items, and that contextual information associated with the items was recalled with great difficulty regardless of suppression or rehearsal. The design of Experiment 1 was then simplified from using a matrix of 9 items, to using sets of 3 items (i.e., item triads) for Experiment 2. Experiment 2 found participants generally unable to suppress items situated within item-triads, and contextual information remained unaffected by suppression and rehearsal. In two experiments the imagined-event Think/No-think paradigm (iTNT) was used to test participant ability to suppress episodic information that was generated specifically for experimental purposes, and would thus be unlikely to have been previously rehearsed or suppressed. Individuals were able to suppress targets associated with emotionally negative imagined future events (Experiment 3), but were unable to suppress the gist recall of imagined past or future events (Experiment 4). A combined analysis revealed differences in suppressive capabilities between low, medium, and high neuroticism scores. Mid-neuroticism participants were readily able to suppress targets associated with emotionally negative imagined future events, but not imagined past events. High-neuroticism participants experienced a significant rebound effect for emotionally negative past events. Lowneuroticism participants were generally unable to suppress, but did not demonstrate significant rebound effects. Individual differences in suppressive capabilities are discussed in relation to related research using various thought suppression paradigms. The relationship between thought suppression efficacy and neuroticism provides support of the executive deficit hypothesis, as neuroticism is highly correlated with executive control. Convergent evidence from paradigms measuring other personality traits that correlate with executive control and thought suppression on the TNT paradigm is discussed.