Using acute stress to improve episodic memory: The critical role of contextual binding.

Previous research has shown that encountering a brief stressor shortly after learning can be beneficial for memory. Recent studies, however, have shown that post-encoding stress does not benefit all recently encoded memories, and an adequate theoretical account of these effects remains elusive. The current study tested a contextual binding account of post encoding stress by examining the effect of varying the context in which the stressor was experienced. Participants encoded a mixture of negative and neutral images, immediately followed by a stressor (i.e., socially evaluated cold pressor) or a non-stress control task. Half of the participants received the stress/control manipulation in the same context as the study materials and half were moved to another context (i.e., a different room with a different experimenter). Two days later all participants returned to the original study room and received a recognition memory test. The results indicated that stress increased recognition memory only when the stressor occurred in the same context as the study materials, whereas stress did not benefit memory if the stressor occurred in a different context. Moreover, stress related increases in salivary cortisol were related to increases in memory when the stressor occurred in the same context as the study materials but not when the context changed. Similar effects were observed for negative and neutral materials and for males and females. These results are consistent with a contextual binding account and suggest that stress acts on memory by enhancing the encoding of the ongoing context of the stressor which benefits memory for the immediately preceding events that share the same context.