Prediction Errors in Depression: A Quasi-Experimental Analysis.

The overprediction and underprediction of fear, pain, and other constructs have been linked with etiology and maintenance of anxiety disorders. We aimed to extend this research to depression by investigating the overprediction of effort and the underprediction of reward and enjoyment associated with a simple task. Participants with depression (n = 20) and a control group (n = 40) predicted how much effort and reward/enjoyment would be experienced during a short walk around the university. Post-walk, participants reported the actual effort required and the actual experienced reward and enjoyment. Compared to the control group, who demonstrated accurate predictions, depressed individuals significantly overpredicted the required effort associated with the walk even though there were no between-group differences in actual effort required. There was no evidence to suggest that the depressed group underestimated or were inaccurate in their predictions of walk-related reward and enjoyment relative to the control group. Implications for cognitive and behavioral approaches to depression are discussed.

Repeated checking really does cause memory distrust.

Memory phenomena associated with obsessive-compulsive disorder (OCD) have received increased attention in the recent literature. Some debate remains about whether OCD is characterized by deficits in memory per se, or by poor memory confidence. Following from a recent study that demonstrated memory distrust results from repeated checking of a virtual computerized stove, we asked 50 undergraduate students to repeatedly turn on, turn off and check either a real kitchen stove (relevant checking) or a real kitchen faucet (irrelevant checking) in a standardized, ritualized manner. All participants completed a final check of the stove following these 19 checking trials. Results indicated that following repeated relevant checking, participants reported significantly reduced memory confidence, vividness and detail. Repeated irrelevant checking did not produce these decreases. Results are discussed in terms of cognitive-behavioural formulations of OCD and in terms of the effects of repetition on memory and metamemory.