psychotherapy:

Evidence suggests that mind wandering is a frequent accompaniment to an unhappy mood. Building on such work, two laboratory experiments used mood induction to assess whether the greater frequency of mind wandering in a low mood is also accompanied by a shift towards a focus on events from the past. Experiment 1 induced moods via video and induction of an unhappy mood was associated with a greater tendency for past-related mind wandering as measured by a post-task questionnaire. In Experiment 2, negative and positive moods were induced in a group of participants using the Velten mood-induction procedure and the temporal focus of mind wandering was measured using experience sampling probes. Analyses indicated that induction of an unhappy mood led to an increase in past-related mind wandering and the magnitude of this change increased with scores on a measure of depressive symptoms. Together these experiments suggest that when the mind wanders in an unhappy mood it is drawn to events from its past.