Gender Differences in Working Memory Performance as a Function of Sex Hormone Levels

PSY2031 Lab Report

Gender Differences in Working Memory Performance as a Function of Sex Hormone Levels

Introduction

In today’s society stereotypes between genders seems to be ubiquitous. As a result, there is growing interest in the exploring the accuracies, or rather the inaccuracies, of such stereotypes. A meta-analysis conducted by Swim (1994) looks into the accuracy of gender stereotypes suggesting that there are accuracies to such stereotypes and not necessarily overestimates. However, several studies such as this one rely on one major assumption: what people actually do and what they say or believe they do are the same. Such assumptions may be problematic as there is a large disparity between the two. Ultimately, this disparity means that surveys and questionnaires aren’t very reliable tools for testing the validity of stereotypes. Although the focus of this paper isn’t a study on stereotypes and their validity, it does indirectly investigate a common stereotypes associated with gender and cognitive function.

This present study is interested in sex differences in working memory. Working memory is said to be an “executive function” of the brain in that it is very important for reasoning and guiding decision making and behaviour (Diamond, 2013). Often used synonymously with short-term memory, working memory is actually the ability to hold information in the short-term while simultaneously processing it (Diamond, 2013). We rely on the use of our working memory for everyday activities as well as the navigation of complex tasks such as comprehension, learning and reasoning (Baddeley, 2010).

Men are often said to be more competent in spatial working memory tasks such as wayfinding or learning a route or a sequence of places whilst women are often said to more competent at verbal memory tasks and remembering and recalling specific details [insert reference-1]. There have been several studies that have looked at the sex differences in cognitive function. Chipman & Kimura’s (1998) studies on incidental memory showed that females were better at verbal learning compared to men whereas men performed better than females in mental rotations and spatial tasks.

In order to further explore the sex differences observed in cognitive function, researchers have conducted studies on the brain to try and indicate which regions of the brain may be responsible for different types of cognitive function. Extensive research compiled by (Duff & Hampson, 2001) found that there was activation of the prefrontal cortex during spatial working memory tasks. Furthermore, Goldstein et al. (2005) was able to determine that the performance of spatial working memory tasks activated the prefrontal, parietal, cingulate and insula regions of the brain.  Some researchers have suggested that the prefrontal cortex may be sexually differentiated in humans due to differing levels of sex hormone activity on the pre-frontal cortex (Duff & Hampson, 2001).These differences in sex hormone activity in males and females could explain the differences observed in working memories.

Past research has suggested that sex hormone levels are associated with the 2D:4D ratio. The 2D:4D ratio is the ratio of the second digit to fourth digit length on the hand (Kalmady et al., 2013). Specifically, (Hönekopp et al., 2007) found that there was a correlation between right hand 2D:4D ratio and sex hormones such as testosterone, follicle stimulating hormone (FSH) and Luteinising hormone (LH).

A smaller ratio is typical in males and indicates higher levels of testosterone whereas females usually have smaller ratios which indicate lower testosterone levels. Consequently, sex hormone levels can be measured as a function of 2D:4D ratios (Malas et al., 2006)

This present study therefor sets out to further investigate where there are gender differences in working memory, and if do, the nature of that difference. On the basis of previous research, which has found a significant relationship between lower 2D:4D ratios and better working memory performance, it is predicted that females will have a larger 2D:4D ratio than men. It was also hypothesized that working memory would significantly differ between genders and finally, it was predicted that is a relationship between 2D:4D ratio for each gender and their performance on working memory tasks.

Methods

Participants

There were 497 participants (385 females, and 112 males), undergraduate psychology students enrolled at Monash University during semester one 2016. Participants were aged between 18 and 64 years (M = 23.366, S = 7.48). Participants took part in the study wittingly, meaning they were completely aware about the aims of the study. Participation was voluntary.

Design

This study used a quasi-experimental design. The independent variable was gender (male or female). There were two depended variables: 2D:4D ratio and spatial working memory.

Materials

Reaction time and accuracy associated with spatial working memory was measured using an online simulation program, the n-back test. (http://cognitivefun.net/test/23). A see-through ruler with millimetre units was used to measure the 2D:4D ratio.

Procedure

The participants completed an on-line stimulation task via “CognitiveFun”. This task involved remembering where dots were located on a 3x3 grid cell and following their location as the dot moves around the cell as indicated by sets of appearing arrows. After the arrows stop appearing the location of the dot is indicated by pressing the keypad number that corresponded to the correct cell. This task consisted of ten trials and reactions times and accuracy was given as an average of the ten trials.

Participants were also asked to calculate their 2D:4D ratio by measuring the length of their index finger (2D) and their ring finger (4D) from the bottom crease of the finger to the end of the finger in millimetres. Once the distances had been measured the ratio was calculated by dividing the length of the index finger by the length of the index finger (i.e. 2D / 4D).

Once the online task and the 2D:4D ratio had been measured, participants were asked to enter their data into an online questionnaire. The questionnaire required participants to enter their age, gender, task accuracy, task reaction time and 2D:4D ratios.

Results

In order to determine whether or not there was a gender difference in the 2D:4D ratio and the performance on working memory tasks, and also if there was a relationship between the variables, independent-samples t-tests and a Pearson’s correlation was used. SPSS Statistics 20 was used to process the data.

On average, males (M= 81.85, S=16.40) had a higher working memory accuracy than females (M= 77.45, S = 18.12), with a mean difference of 4.40%. Males also had a great working memory reaction time (M = 968.6, S= 443.5) in comparison to females (M=967.3, S = 414.3), with an average mean difference of 1.3ms. Females also had a larger 2D:4D ratio 0.981 than males 0.964, with a mean difference of 0.02.