The role of cognitive inhibition in emotion regulation: is weak cognitive inhibition related to ruminative style and failed attempts at thought suppression?
University of New Brunswick
Trait rumination is considered a vulnerability factor in major depression (NolenHoeksema, Wisco, & Lyubomirsky, 2008). It has been suggested that rumination is characterized by weak inhibitory processes, which contributes to the uncontrollable nature of negative thoughts thereby increasing risk for depression (Joormann, 2005). However, questions remain on whether the link between inhibition and rumination may be attributed to comorbid depressive symptoms. Therefore, the current study extended previous research by investigating whether ruminative style is associated with deficits in inhibition ability, while controlling for depression status. Furthermore the present dissertation took an initial step by investigating whether inefficient inhibition predict reduced ability to suppress upsetting thoughts during an induced sad mood state. It was hypothesized that high trait rumination would be associated with weak cognitive inhibition, independent of a major depressive disorder, and that weak inhibitory processes characteristic of depressed or high ruminator groups would predict increased intrusions and prolonged sadness following thought suppression attempts. Participants (N = 218) completed a list-version directed forgetting task as a measure of cognitive inhibition, and were assigned to suppression or monitor only conditions following a six minute sad movie induction. Thought suppression was measured by number of movie-related thoughts, whereas perceived suppression ability was measured by self-report difficulty ratings for the task. Mood rating scales were administered at four time periods to track reactivity and recovery from induced sad mood. A select group of high and low vulnerability individuals (n =148) with extreme scores on trait rumination were divided into experimental groups (i.e., depressed/high ruminator, high ruminator/nondepressed, low ruminator/nondepressed), labeled depressed, high ruminator and low ruminator groups, respectively. Overall there was mixed support for the hypotheses. Specifically, high ruminators, but not depressed individuals, demonstrated weak inhibition. There was no evidence to suggest deficits were specific to inhibition of negative information. Furthermore, high ruminators perceived more difficulty in suppressing movie-related thoughts compared to depressed and low ruminator groups. Contrary to hypotheses, weak inhibition did not predict difficulty with thought suppression and surprisingly, was associated with fewer overall movie-related thoughts. Results and implications were discussed in terms of potential vulnerability factors for depression.