The impact of acute psychological stress on declarative and working memory functioning

Includes bibliographical references (leaves 94-102).Previous research has shown that stress affects processing in many different memory systems. This study aimed to investigate the effects of acute psychosocial stress on declarative memory (DM) and working memory (WM) performance, and to explore whether sex differences exist under stress in these two memory systems. DM was assessed using cued recall and recognition of a verbal paired-associates list. WM was assessed using an n-back test with various difficulty levels. One hundred (42 males) undergraduate psychology students from the University of Cape Town were recruited. Phase of menstrual cycle and oral contraceptive use were controlled for in female participants. Participants took part in two sessions, 24 hours apart, each beginning after 16h00. Day 1 involved learning and immediate cued recall of the word pairs, and completing a practice n-back protocol. During Day 2, 45 participants were exposed to a psychosocial stressor and 41 were exposed to a relaxation period. Physiological and self-report measures of stress were taken at three intervals pre- and post-experimental manipulation. Participants then completed delayed cued recall and recognition tests for the previously-learned word pairs, and the full version of the n-back test. Data were analysed only for participants characterised as 'cortisol responders' following the experimental manipulation. The final sample included 57 participants (30 males). With regard to DM, stress did not affect either delayed cued recall or recognition performance in either men or women. With regard to WM, stress negatively affected accuracy among men, but not women. These results are largely consistent with previous literature, but also elucidate a sex difference in working memory performance under stress (viz., while men's performance is negatively affected by stress, women show improved performance). The study provides important evidence for sex differences in WM performance under stress, and highlights several methodological issues that should be addressed in future studies