Task-unrelated thoughts and forgetting in working memory

The present article reports four experiments that investigated the effects of task-unrelated thoughts (TUTs) on forgetting in non-verbal working memory. Participants had to remember three non-verbal stimuli over unfilled retention intervals (RIs) and then judge whether or not a subsequently presented probe stimulus matched one of the to-be-remembered stimuli. Participants additionally responded to randomly appearing probes that measured different aspects of their TUT engagement during the RI of the preceding trial. Forgetting over unfilled RIs was observed in three of four experiments and reliably associated with the proportion of time spent on TUTs. In contrast, the visual and auditory nature of the TUTs and the number of different TUTs did not reliably predict forgetting. The results support the view that TUTs block attention-based processes that are needed for restoring decaying memory representations rather than an alternative account in terms of interference caused by the content of the TUTs.