The testing effect refers to the phenomenon that repeated retrieval of memories promotes
better long-term retention than repeated study. To investigate the neural correlates
of the testing effect, we used event-related functional magnetic resonance imaging
methods while participants performed a cued recall task. Prior to the neuroimaging
experiment, participants learned Swahili-German word pairs, then half of the word
pairs were repeatedly studied, whereas the other half were repeatedly tested. For
half of the participants, the neuroimaging experiment was performed immediately after
the learning phase; a 1-week retention interval was inserted for the other half of
the participants. We found that a large network of areas identified in a separate
2-back functional localizer scan were active during the final recall of the word pair
associations. Importantly, the learning strategy (retest or restudy) of the word pairs
determined the manner in which the retention interval affected the activations within
this network. Recall of previously restudied memories was accompanied by reduced activation
within this network at long retention intervals, but no reduction was observed for
previously retested memories. We suggest that retrieval promotes learning via stabilizing
cue-related activation patterns in a network of areas usually associated with cognitive
and attentional control functions.
