Investigating Gender Differences in Spatial Working Memory Performance: The Role of Sex Hormone Levels.

Investigating Gender Differences in Spatial Working Memory Performance: The Role of Sex Hormone Levels.

My Bui

Submitted as PSY2031 Laboratory Report

Due date: 21st April

Tutor: Lauren Den Ouden

Class: Thursday, 8:00-10:00

Abstract

This study investigated whether there are gender differences in spatial working memory, taking into consideration hormone levels by using the 2D:4D ratio as an indicator of testosterone levels in the utero. Also, to explore relationships between the 2D:4D ratio and working memory. Participants consisted of 385 female and 112 male undergraduate psychology students from Monash University, mean age 23.4 years (SD = 7.48). The participants were asked to perform an n-back test accessed online, and calculate their 2D:4D ratios. It was hypothesised that there will be a difference in working memory performance amongst the genders, furthermore, that there is relationship between spatial working memory performance and the 2D:4D ratio. It is concluded that males (with the lower 2D:4D ratios) performed better on the n-back test than females, providing support for the notion of gender differences in working memory.

Introduction

There has been plenty of interest into finding psychological differences between males and females. Sex hormone levels and brain lateralization has been linked to strengthened cognitive performance, and in turn is an area that is given substantial research efforts when looking for gender differences in working memory (e.g., Hill, Laird & Robinson, 2014, Kalmady et al., 2013). This laboratory report aims to investigate testosterone (measured by the 2D:4D ratio) and its role in determining possible gender differences in working memory and its relationship with working memory.

Working memory’s link to learning and intelligence has been widely acknowledged; as it has been confirmed to play a role in manipulating information entering the cognitive system, temporarily storing information and regulating attention; functions crucial to learning (Hill et al. 2014). On a performance perspective, males have demonstrated stronger performances in mathematical, spatial and object working memory, whereas females dominate over males in verbal and writing skills (Burton, Henninger and Hafetz, 2010). The differences in cognitive performances have prompted research into discovering why there are differences and to what extent do these differences affect task performance (Lohman & Lakin, 2009)

Research undertaken by Burton, Henninger and Hafetz (2010) aimed to establish relations between finger length ratios and cognitive skills, and discover cognitive differences in genders. A mental rotation and written verbal fluency test was employed to examine the differences. Duff & Hampson (2001) also employed a mental rotation test, likewise to Burton et al results revealed superior performance from males. Lynn & Irwing’s results also showed younger males and adult males performed better in cognitive skills involving mental rotation and younger females and adult females performed better in verbal fluency.

The 2D:4D ratio lends itself as a marker for testosterone levels in the utero, the ratio tends to be smaller in men than women, indicative of higher levels of testosterone; which in turn has been linked to better cognitive performance (Kalmady et al. 2010). Below-average 2D:4D ratios or low levels of testosterone has been linked to neurological disorder, impaired cognitive functioning and left-handedness (suggestive of stronger right hemisphere lateralization) (Kalmady et al. 2010).

Kalmady et al. (2010) found that men who had lower 2D:4D ratios performed better than women who had larger 2D:4D ratios. Furthermore, women who had a lower ratio on their right hand (signs of strengthened left “analytical” hemisphere) performed better on the 2-Back task (increased difficulty of the n-back test) than women who had a greater ratio on their right hand, indicating that lower 2D:4D ratios have a positive correlation with higher scores on the 2-Back test. This provides motive for both of the present study’s hypotheses, the first being that there is a gender difference in working memory, and that there is a relationship between the 2D:4D ratio and working memory.

According to Hill et al. (2013) differences in cognitive function may be a result of differences in cognitive processing. To determine the differences in cognitive processing Hill et al employed a simple working memory test; remembering coordinates, whilst the participants were remembering the coordinates; using the BrainMap Database they mapped out the different cortical areas activated while participants tried to remember the coordinates. Results showed that the working memory task triggered different cortical activations depending on the gender of the participant; in females, the limbic system and the prefrontal network was activated (including the bilateral middle frontal gyri) whereas for males the task triggered activation in the cerebellum, portions of the superior parietal lobe, the left insula and the bilateral thalamus. Despite the differences in cortical activation, results on the test revealed no statistically significant difference on the working memory performance likewise to Goldstein et al. (2005). These studies addressed the first hypothesis on a neurological perspective; evidence showed differences in working memory were due to differences in brain activations when performing tasks.

Previous studies have reported mixed findings on cognitive performance differences in genders. The present study aims to investigate whether there are gender differences on a specific cognitive ability, spatial working memory. Some correlative studies revealed that males based on their tendency to have lower 2D:4D ratios, had a positive correlation with better cognitive performance. This has provided reasoning for the first hypothesis whereby it was hypothesised that males will perform with better accuracy and reaction time on the n-back test than females who tended to have higher 2D:4D ratios. Differing from other previous research, this study has added “reaction time” as a component of working memory performance. The second hypothesis anticipates a positive correlation with lower 2D:4D ratios and working

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