Criterial learning is not enough: Retrieval practice is necessary for improving post-stress memory accessibility.

In a recent study, having participants make three retrieval attempts (i.e., retrieval practice) when learning information strengthened memory against the detrimental effects of psychological stress. We aimed to determine whether learning to criterion, in which only one successful retrieval attempt is made, would similarly buffer memory against stress, or whether multiple retrieval attempts are necessary to achieve that effect. In Experiment 1, participants learned to criterion and then engaged in additional restudying (CLS) or retrieval practice (CLR). Twenty-four hours later, stress was induced and stress-related increases in cortisol were observed. However, no differences in recall performance were observed between any of the groups. Experiment 2 was similar but introduced a 1-week delay between encoding and retrieval. Recall performance was impaired for both groups under stress, but recall for those in the CLR group was still better than either pre- or post-stress performance for those in the CLS group. Thus, criterial learning may protect memory against stress in the short-term, but additional retrieval practice is more beneficial for achieving this effect in the long-term. (PsycINFO Database Record