Abstract
Aging is characterized by a decrease in visual working memory (vWM) capacity, which has recently prompted the development of various training interventions. The majority of the proposed interventions are long-term behavioral trainings, usually aiming at transferring gains to other untrained cognitive tasks/domains. Thus, whether short practice (i.e. simple task repetition over a brief period of time), could be as effective as the above mentioned trainings in boosting vWM has remained surprisingly little explored. Investigating short-practice effects is, indeed, a relatively simple and rapid way to evaluate whether a specific ability can be improved in the elderly. By combining behavioral and electrophysiological (EEG) indexes we investigated the effects of short-term vWM practice in young and older participants performing a vWM task over 4 consecutive days. Behavioral results indicated larger improvements in older participants, who increased in both sensitivity (d’) and vWM capacity (k), and ultimately reduced the gap in vWM limit with the young counterparts. The behavioral outcomes were supported by practice effects observed in EEG responses. In both groups, attentive individuation (reflected by the N2pc) was modulated by target numerosity only after practice (in line with d’ results). Moreover, in young participants, the Contralateral Delay Activity (CDA), a neural correlate of item maintenance in the WM buffer, indexed target numerosity across all sessions; in the elderly, the CDA was modulated by the different memory loads only after practice (in line with k values). The results indicate that practice acts through modifications at different levels of stimulus processing, and in turn suggest that the age-related WM decrease can be caused by different deficient mechanisms. Specifically, our data showed that practice can effectively improve vWM of older individuals by enhancing the selective individuation of the target elements, with a cascade effect on their memorization.