Rumination burdens the updating of working memory

Working memory is a vital, but capacity-limited, cognitive instrument that requires frequent updating as our goals and environment change. Individuals diagnosed with depression have a reduced capacity compared with the general population, as they have a propensity to fixate on negative information, even when it is not relevant for the task at hand. Here we investigated how characteristics of psychiatric illnesses, such as rumination, affect a person's ability to efficiently update emotional information in mind. We used both neutral and negative pictures of scenes in a working memory updating task that required participants to occasionally replace items held in mind during a brief delay period. Participants were presented with a probe item at the end of each trial and asked to report whether that item was in their current memory set. Responses were slowest and least accurate for images that had been replaced (i.e., "lures"), indicating there was some difficulty in successfully updating working memory in this paradigm. Participants who have both a high propensity to ruminate and a low working memory capacity were significantly more likely to false alarm to these lures. While emotional valence did not impact accuracy for these participants, their false alarms were faster for negative stimuli compared with neutral stimuli, indicating that task-irrelevant emotional information was more difficult to remove from working memory. These results demonstrate how rumination impairs goal-directed behavior by obscuring the boundary between relevant and irrelevant information in working memory.