The interactive effects of divided attention and semantic elaboration on associative recognition memory: an fMRI study.

The present study explored the opposing effects on memory of semantic elaboration and division of attention on learning and recognition of verbal paired associates. Previous work had found that levels of recollection were reduced under divided attention conditions, even after equating expressed elaboration levels between full and divided attention. The present experiments not only confirmed this finding but also found that participants based their expressed levels of elaboration largely on normative values rather than on subjectively achieved levels of elaboration. In terms of related brain processes, experiment 2 used functional magnetic resonance to show that division of attention was associated with reduced levels of both prefrontal and hippocampal activity and with a reduction in connectivity between the anterior hippocampus and medial-orbital regions of the prefrontal cortex. Increased levels of elaboration were associated with increased activity in prefrontal regions immediately after stimulus presentation. Additionally, connectivity between the hippocampus and medial-prefrontal cortex was enhanced by increases in elaboration under full attention but reduced by increases in elaboration under conditions of divided attention. Our results therefore show that two factors influencing memory-elaboration and attention-are mediated largely by processes in the prefrontal cortex, the hippocampus, and the functional connectivity between these two structures.