Psy 2031 Lab Report

Abstract

Current literature has suggested that that the pre-frontal cortex may be sexually differentiated in humans due to the actions of sex hormones. This study aims to further investigate the gender differences in working memory performance. Participants consisted of 497 undergraduate psychology students from Monash University with a mean age of 23.4 years. Participants completed an online simulation, n-back test, along with measuring their own 2D:4D ratios. The results supported our hypotheses that females will have a larger 2D:4D ratios than males, and there are gender differences in working memory performance, with males completing the working memory task more accurately. The hypotheses that there is a relationship between 2D:4D ratio and performance in working memory tasks wasn’t supported by the results. Future applications of this study may lead to a development of therapies that may be used to increase the growth and development of brain regions key to working memory performance.

Introduction

In today’s society stereotypes between genders seems to be ubiquitous. Consequently, there is growing interest in the exploring the accuracies, or rather the inaccuracies, of stereotypes. A meta-analysis conducted by Swim (1994) looks into the accuracy of gender stereotypes suggesting that there are accuracies to such stereotypes and stereotypes are not necessarily overestimates. However, several studies such as this one rely on the use of surveys and questionnaires. This is problematic because such modes of data collection rely so heavily on the assumption that what people report about themselves actually reflects what their actions and thoughts in reality. However this may not always the case and there may be a disparity between the two ultimately making it difficult to draw rigid conclusions from such studies. This present study, however, isn’t concerned with investigating the validity of stereotypes but it does however indirectly test at a common stereotype associated with gender differences and cognitive function.

This study is interested in sex differences in working memory. Working memory is said to be an “executive function” of the brain important for reasoning, 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 (Baddeley, 2010). Several studies have looked at the sex differences in cognitive function. For example, 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 determine which regions of the brain are responsible for different types of cognitive function. Extensive research compiled by Duff and 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. It has been 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) and thus these differences in sex hormone activity in males and females could explain the differences detected 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). Hönekopp et al. (2007) found that there was a correlation between right hand 2D:4D ratio and sex hormones such as testosterone. A smaller ratio is typical in males and indicated higher levels of testosterone whereas females usually have larger ratios which indicate lower testosterone levels. These studies have allowed for sex hormone levels to be indirectly measured as a function of 2D:4D ratios (Malas et al., 2006)

This present study therefor sets out to further investigate whether there are gender differences in working memory, and if so, the nature of these differences. On the basis of previous research, which has found a 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 there 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. Participants were aged between 18 and 64 years (M = 23.366, S = 7.48). Participants took part in the study as part of their assessment for the course. 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 a dot was located on a 3x3 grid cell and following its location as the dot moved around the 3x3 grid, as indicated by sets of consecutive appearing arrows. After the arrows stop appearing, the participants indicated the new location of the dot by pressing the keypad number that corresponded to the correct cell in the grid. This task consisted of ten trials and reactions times and accuracy was given as an average over

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