Retrieval practice improves memory in survivors of severe traumatic brain injury

To investigate whether retrieval practice (RP) improves delayed recall after short and long delays in survivors of severe traumatic brain injury (TBI) relative to massed restudy (MR) and spaced restudy (SR).

3(learning condition: MR, SR, RP)×2(delayed recall: 30min, 1wk) within-subject experiment.

Nonprofit medical rehabilitation research center.

Memory-impaired (<5th percentile) survivors of severe TBI (N=10).

During RP, patients are quizzed on to-be-learned information shortly after it is presented, such that patients practice retrieval. MR consists of repeated restudy (ie, cramming). SR consists of restudy trials separated in time (ie, distributed learning).

Forty-eight verbal paired associates (VPAs) were equally divided across 3 learning conditions (16 per condition). Delayed recall for one half of the VPAs was assessed after 30 minutes (8 per condition) and for the other half after 1 week (8 per condition).

There was a large effect of learning condition after the short delay (P<.001, η(2)=.72), with much better recall of VPAs studied through RP (46.3%) relative to MR (12.5%) and SR (15.0%). This large effect of learning condition remained after the long delay (P=.001, η(2)=.56), as patients recalled 11.3% of the VPAs studied through RP, but nothing through MR (0.0%) and only 1.3% through SR. That is, RP was essentially the only learning condition to result in successful recall after 1 week, with most patients recalling at least 1 VPA.

The robust effect of RP among TBI survivors with severe memory impairment engenders confidence that this strategy would work outside the laboratory to improve memory in real-life settings. Future randomized controlled trials of RP training are needed.