The impact of acute psychological stress on spatial cognition

Master Thesis


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University of Cape Town

Based on the premise that the hippocampus is both affected by cortisol and intimately involved in episodic memory and spatial cognition, the general aim of this study was to investigate the effects of psychosocial stress (and consequent cortisol increase) on spatial cognition and verbal memory in men and women. One group of 33 participants (16 males and 17 females) were exposed to the Trier Social Stress Test (TSST; Kirschbaum, Pirke, & Hellhammer, 1993), a procedure designed to induce mild psychosocial stress. I used 3 different means to check the effectiveness of this stress induction: salivary cortisol, self-report via the Spielberger State-Trait Anxiety Inventory, and heart-rate measurements. The measures all converged to suggest that the stress induction procedure was successful. A control group of29 participants (15 males and 14 females) was exposed to a relaxation period rather than the TSST. Following this part of the experimental protocol, all participants completed a virtual environment spatial navigation task and a word-list learning and recall task. Results showed that, on the spatial navigation task, females and males who were not exposed to the stressor located and relocated a hidden target equally well (Le., cognitive map-guided navigation was intact in unstressed participants). In addition, on the spatial navigation task the interaction effect of the gender and experimental condition approached statistical significance (p = 0.085), suggesting that females exposed to the stressor required more time to locate and relocate a hidden target than did the other participants (Le., they were disrupted in their cognitive map-guided navigation). On the verbal memory task, participants who showed larger cortisol increases following exposure to the TSST tended to recall fewer words than did those with smaller cortisol increases, with a slightly stronger negative correlation in males than in females. The data therefore confirm that stress impacts different memory systems in different ways, and, perhaps more importantly, that sex differences play a role in moderating those effects. This is the first demonstration, within a single study, of a possible double dissociation of sex differences in cognitive performance following induction of mild psychosocial stress.

Includes bibliographical references (leaves 54-64).