Recollection after inhibition: The effects of intentional forgetting on the neural correlates of retrieval

Intentional forgetting is posited to utilize both encoding and inhibition to control what information enters long-term memory. Within the context of the directed forgetting paradigm, evidence for the role of inhibition to support forgetting has been examined primarily during encoding. Specifically, past studies have shown that when encoding processes are intentionally inhibited, information is less likely to be remembered. Despite the recruitment of such inhibitory processes, not all items are successfully forgotten. The current study examined whether items that should have been forgotten (F items), but were ultimately recollected, showed neural evidence at retrieval of having previously undergone attempted inhibition, particularly when compared to items that received “remember” instructions (R items). Results indicate that recollection of F items engaged additional activity in the prefrontal cortex, including the right inferior frontal gyrus and right superior frontal gyrus, suggesting that retrieval of these items required greater effort, most likely due to inhibitory processes that were engaged at encoding. These results suggest that inhibitory processing during attempted but unsuccessful forgetting can result in a more difficult retrieval period.