Impaired selection of relevant positive information in depression.

BACKGROUND: A hallmark characteristic of depression is the inability to regulate the effect of emotional material on cognition. Previous research has demonstrated that depressed individuals are less able than are nondepressed persons to expel irrelevant negative information from working memory (WM), thereby exacerbating the effects of negative content on cognition. The primary goal of this study was to examine whether depressed individuals are also impaired at selecting relevant positive content in the context of representations competing for resources in WM; such an impairment would limit depressed persons' ability to use positive material to ameliorate the cognitive effects of negative information.
METHODS: We administered a Recency-probes task with neutral, positive, and negative words to 20 currently depressed and 22 never-depressed participants. This task assesses the selection of relevant content in WM by inducing interference between current and prior representations of a stimulus in WM. Reaction times to interference and noninterference trials were compared across valence and group to assess how effectively depressed individuals select task-relevant emotional content to resolve interference.
RESULTS: Compared to never-depressed controls, depressed individuals were impaired in selecting task-relevant positive stimuli; the performance of the two groups was comparable for selecting task-relevant neutral and negative stimuli.
CONCLUSIONS: Findings indicate that a valence-specific deficit in WM may contribute to the inability of depressed individuals to regulate emotion, and provide empirical support for formulations that implicate positive insensitivity in the maintenance of depression.