Reducing the Consequences of Acute Stress on Memory Retrieval

The Forward Testing Effect Is Resistant to Acute Psychosocial Retrieval Stress

The forward testing effect refers to the finding that testing of previously studied information improves memory for subsequently studied newer information. Recent research showed that the effect is immune to acute psychosocial encoding/retrieval stress, i.e., stress that is induced before initial encoding. The present study investigated whether the forward testing effect is also robust to acute psychosocial retrieval stress, i.e., stress that is induced after encoding but before retrieval of the critical item list. Participants (N = 128) studied three lists of words in anticipation of a final cumulative recall test. Participants were tested immediately on Lists 1 and 2 (testing condition) or restudied the two lists after initial study (restudy condition). After study of the critical List 3, psychosocial stress was induced in half of the participants (stress group), whereas no stress was induced in the other half (control group). The Trier Social Stress Test for Groups (TSST-G) was used for stress induction. Salivary cortisol, alpha amylase, and subjective stress were repeatedly measured. The results of the criterion test showed a generally detrimental effect of psychosocial retrieval stress on List 3 recall. Importantly, the forward testing effect was unaffected by retrieval stress. The findings are discussed with respect to current theories of the forward testing effect.

Stress and long-term memory retrieval: a systematic review

Introduction

The experience of stressful events can alter brain structures involved in memory encoding, storage and retrieval. Here we review experimental research assessing the impact of the stress-related hormone cortisol on long-term memory retrieval.

Method

A comprehensive literature search was conducted on PubMed, Web of Science and PsycNet databases with the following terms: “stress,” “long-term memory,” and “retrieval.” Studies were included in the review if they tested samples of healthy human participants, with at least one control group, and with the onset of the stress intervention occurring after the encoding phase and shortly (up to one hour) before the final memory test.

Results

Thirteen studies were included in the qualitative synthesis (N = 962) and were classified according to the time elapsed between stress induction and memory retrieval (stress-retrieval delay), the stress-inducing protocol (stressor), the time of day in which stress induction took place, sex, and age of participants. Most studies induced stress with the Trier Social Stress Test (TSST) between 15 and 25 minutes before the final memory (mostly recall) test and showed significant increases in cortisol levels and memory impairment.

Discussion

The reviewed studies indicate that stress does impair retrieval, particularly when induced with the TSST, in the afternoon, up to 45 minutes before the onset of the final memory test, in healthy young men. These results may inform future research on the impact of stress-induced cortisol surges on memory retrieval.

The Forward Testing Effect is Immune to Acute Psychosocial Encoding/Retrieval Stress

The forward testing effect (FTE) refers to the finding that testing of previously studied information enhances memory for subsequently studied other information. Previous research demonstrated that the FTE is a robust phenomenon that generalizes across different materials and populations. The present study examined whether the FTE is robust under acute psychosocial encoding/retrieval stress. In each of two experimental conditions, participants studied three item lists in anticipation of final cumulative recall testing. In the testing condition, participants were tested immediately on lists 1 and 2, whereas in the restudy condition, they restudied lists 1 and 2. In both conditions, participants were tested immediately on list 3. Acute psychosocial stress was induced in participants prior to the encoding of item lists using the Trier social stress test for groups protocol. No stress was induced in a control group. Salivary cortisol, alpha amylase, and subjective stress were measured repeatedly to capture the biopsychological stress response. The results showed a significant FTE on list 3 recall, that is, testing of lists 1 and 2 enhanced the recall of list 3. No significant effect of stress on the FTE was observed, suggesting that the FTE is robust under acute psychosocial encoding/retrieval stress. The discussion provides suggestions for future research directions.

An oral presentation causes stress and memory impairments

Laboratory experiments revealed the stress hormone cortisol to decrease memory retrieval of emotional material, but a translation to real-life settings is missing so far. In this study, 51 students encoded a list of neutral, positive, and negative words as well as two neutral, biographical notes one day before attendance at a seminar at the university. In the stress condition, students gave a graded oral presentation, whereas they just attended the same seminar in the control condition immediately before retrieval took place. Measures of state anxiety, salivary cortisol and alpha-amylase confirmed the oral presentation to constitute a potent stressor. Importantly, stress significantly impaired retrieval of negative words, but not retrieval of the biographical notes. These results indicate that a real-life stressor decreases memory retrieval for negative items. In contrast, delayed memory retrieval of neutral information and interrelated details of biographical notes seems to be less prone to stress effects. These results have critical implications for educational settings.