Evaluating Memory in Stress Induced Situations: Differences in Stress Levels and Gender

Evaluating Memory in Stress Induced Situations: Differences in Stress Levels and Gender

Todd Reesor

0848899

University of Guelph

PSYC*3370

Harvey H.C. Marmurek

Abstract

Stress has been shown to have an effect on working memory. The current study examined the differential effects of stress on working-memory in males and females. A 2x2 mixed factorial design was used to assess the relationship between the within-subjects condition (neutral and stressed) and the between subjects condition which was gender (male and female), on the total number of correct items on a working memory test. An additional 2x2 mixed factorial design was used to examine the differences in stress before and after the experimental manipulation in males and females. The stress levels of participants were recorded prior to and after the stress condition using a Likert Scale. For the stress condition, stress was induced in participants using a variation of an existing test called the Trier Social Stress Test. A sample of seventy-one University of Guelph students ranging in age from 18-24 were recruited to participate in study. It was hypothesized that firstly, stress would have an effect on working memory, secondly, that stress would have a stronger effect on men than on women, and thirdly, that stress improves working memory performance in men and reduces it in women. The results of the first 2x2 mixed factorial design proved to be statistically insignificant indicating stress did not affect working memory in males or females. However there was a statistically significant main effect in the second 2x2 mixed factorial design indicating that participants had higher stress levels after the stress condition. Explanation for the insignificant results could be due to an unreliable method of inducing stress as well as a small sample size.

        Keywords: working-memory, trier social stress test, likert scale

Evaluating Memory in Stress Induced Situations: Differences in Stress Levels and Gender

        Stress is something that affects all people at some point in their lives. Not being able to balance all the demands from work, a social life, school and family can be profoundly overwhelming. There are techniques and strategies that we learn though experience that aid us in managing our stress levels, but these methods can take years to master. University students are a demographic that may not yet have fully developed stress coping mechanisms leading them to be more stressed than the rest of the population. They have a copious amount of strict deadlines to meet with essays, exams and assignments. Not only do the academic demands induce stress but also the fact that students are supposed to be developing their individual identities for the rest of their lives. In 2011, a study conducted by Rehehr and co-authors found that over 50% of 1600 students at the University of Alberta reported feelings of helplessness and overwhelming anxiety over the duration of 12 months (Rehehr et al., 2011). One can only wonder what kind of impact these feelings of anxiety and stress have on student’s overall performance in their academic studies.

        The current study examined the effects of stress on working memory in both males and females in an attempt to gain insight on how the pressure a University student faces, influences their academic performance. 71 undergraduate students (37 female and 34 male) from the University of Guelph volunteered to participate in this study. A 2x2 mixed factorial design was used to examine the effects of stress and gender on performance on a working memory task. A within-subjects variable was used as the same participants were used in both conditions; a working memory task with no manipulation (neutral condition), and then a parallel version of the working memory task after completing a stress-inducing test (stress condition). A second 2x2 mixed factorial design was used to measure the differences in overall stress levels before and after the experiment in males and females. Stress levels were measured using a self-report Likert scale.

A variation of an existing test called the Trier Social Stress Test was used to induce stress in participants. The Trier Social Stress Test is a well-established laboratory stressor that reliability induces stress in human participants (Schoofs et al., 2013). It was created in 1938 at the University of Trier in Germany. The test combines multiple procedures that were known to induce stress but do not do so reliably when used individually (Schoofs et al., 2013).  It requires participants to prepare and present a verbal presentation on a topic chosen by the researcher on the spot, followed by an arithmetic component. In the original test participants would also be fitted with an IV for blood collection and a heart rate monitor. Most changes from the original test to our variation of the test were made for practical reasons such as removal of the IV and heart rate monitor. We also shortened the length of the presentation and the arithmetic component, giving us more time to include more participants in our study. Schoofs and co-authors used the Trier Social Stress Test to induce stress into participants in order to measure changes in cortisol levels. Cortisol is a stress hormone released in humans that peaks usually around twenty minutes after stress onset (Schoofs et al., 2013). The original Trier Stress Test would give participants a period a time before the presentation to prepare cue cards for when they present. Upon the start of the presentation the researchers would take away the cue cards without warning to induce more stress. This step was removed from the current experiment because it was deceptive.

Qin and co-authors found that psychological stress impairs higher-order cognitive functions such as working-memory (Qin et al., 2009). Specifically the study found that acute stress induced in healthy volunteers significantly reduced working-memory related activity in the dorsolateral prefrontal cortex, and was accompanied by relocation of neural resources away from the executive function networks (Qin et al., 2009). This study supports the first hypothesis that stress does have an effect on working memory.

        Cornelisse and co-authors also used the Trier Social Stress Test in order to measure the implications of psychosocial stress on memory formation in both men and women (Cornelisse et al., 2011). They found that stress enhances recognition memory for emotional versus neutral pictures in male subjects and not females, and also found that stress enhanced working-memory particularly in males (Cornelisse et al., 2011). The researchers hypothesized that the lack of enhancement of performance on working-memory in women may be due to the use of oral contraceptives (Cornelisse et al., 2011). The researchers also state that men have a higher cortisol response to stress than women, which could be due to the women’s menstrual cycle and the use of oral contraceptive (Cornelisse et al., 2011). The findings of this study support the second and third hypothesis that stress would have a stronger effect on men than on women, and that stress improves working memory performance in men and reduces it in women.