Theta oscillations show impaired interference detection in the elderly during selective memory retrieval

Seemingly effortless tasks, such as recognizing faces and retrieving names, become significantly harder as people get older. These age-related difficulties may be partially due to the concurrent activation of related competitors. However, it remains unclear whether older adults struggle with detecting an early interference signal or with suppressing irrelevant competitors once competition is detected. To investigate this question, we used the retrieval practice paradigm, shown to elicit interference, while recording electrophysiological activity in young and older adults. In two experiments, young participants showed the typical Retrieval Induced Forgetting (RIF) effect whereas the elderly did not. Neurally, young adults were more capable to detect interference than the older, as evidenced by an increase in midfrontal theta power (~4-8Hz). This efficient interference detection allowed young adults to recruit inhibitory mechanisms that overcome competition, as traced by a theta power reduction across retrieval cycles. No such reduction was found for the elderly, indicating that the lack of an early interference detection signal renders older adults unable to recruit memory selection mechanisms, eliminating RIF.