Updating positive and negative stimuli in working memory in depression.

Difficulties in the ability to update stimuli in working memory (WM) may underlie the problems with regulating emotions that lead to the development and perpetuation of mood disorders such as depression. To examine the ability to update affective material in WM, the authors had diagnosed depressed and never-disordered control participants perform an emotion 2-back task in which participants were presented with a series of happy, sad, and neutral faces and were asked to indicate whether the current face had the same (match-set) or different (break-set or no-set) emotional expression as that presented 2 faces earlier. Participants also performed a 0-back task with the same emotional stimuli to serve as a control for perceptual processing. After transforming reaction times to control for baseline group differences, depressed and nondepressed participants exhibited biases in updating emotional content that reflects the tendency to keep negative information and positive information, respectively, active in WM. Compared with controls, depressed participants were both slower to disengage from sad stimuli and faster to disengage from happy facial expressions. In contrast, nondepressed controls took longer to disengage from happy stimuli than from neutral or sad stimuli. These group differences in reaction times may reflect both protective and maladaptive biases in WM that underlie the ability to effectively regulate negative affect.