The Relationship Between Gender Differences: The 2d:4d Digit Ratio

The relationship between gender differences, the 2D:4D digit ratio and working memory performance

Mattan Bejerano                                                                 24208930

Abstract:

This study aims to further investigate whether a gender difference exists between results in working memory performance (accuracy and reaction time) and 2D:4D ratio, and if so what the nature of this difference is, what relationship do the variables have. Our study used a sample of 112 male and 385 female students undergraduate psychology students and Monash University with a mean age of 23.37 (SD= 7.48). It was expected based on previous study that

Participants were instructed to complete an online n-back test which consisted of 10 trials as well as calculate their own 2D:4D ratio in millimeters.

In support of the hypothesis females averaged a larger 2D:4D ratio than men and females have a quicker and more accurate working performance than males. A positive relationship was as expected found between the variables of 2D:4D ratio and working memory reaction time between genders. From this we concluded that gender and sex hormones have a positive correlation with working memory performance and 2D:4D ratio.

Introduction:

The study of gender equality and gender differentiation has lead to the rise in

discussion about how sex hormones affect human behavior.

Many studies have been conducted to determine whether sex hormone levels and gender differences have been linked to differences in working memory performance, spacial awareness and the 2D:4D ratio.

This study aims to investigate the effect that gender differences have on working memory (WM) and 2D:4D ratio.

Many studies have conducted the relationship between sex hormones and digit ratio as well as digit ratio and working memory, but little investigation has been conducted to analyze the correlation between all 3 variables.

This study which is comparing the results the n-back online simulation and the 2D:4D digit ratio between gender is a further contribution to the analysis of the correlation between 3 separate variables is a further test and an opportunity to assess the accuracy of the hypotheses that WM is influenced by 2D4D and the results for this difference varies based on gender.

Duff and Hampson (2001) conducted a study to investigate the relationship between gender difference and spacial working memory (SPWM) and they established a strong relationship between performance in spacial working memory and activation in the prefrontal cortex. Supporting their findings Courtney (1998), Kalmady et al. (2013) Goldstein (2005) conducted studies using Functional MRI to positively associate the prefrontal cortical brain activity with spacial awareness and working memory performance. Where Goldstein’s study was different was it investigated the sex effects “in auditory and verbal        

working memory task in the prefrontal, parietal, cingulate and insula regions”,

not only the spacial working memory. Collaer and Hines (1995) reported gender  difference in verbal fluency visual spacial skills and motor function.

Researchers such as Sutcliffe et al (2006) and Gur (2000) have found that the influence of sex and hormone difference in spacial task performance could be explained by influence to regions of the brain such as the hippocampus which is said to have significant influence on the performance of working spacial memory. Sutcliffe et al (2006) found that females should be better than males at remembering the identity of object and that males were superior to females at remembering the identity and location of objects and males would overall excel at all SPWM tasks.

Based on several studies it is hypothesized that When assessing the influence of gender on WM performance (reaction time and accuracy) and the 2D:4D ratio it was hypothesized that females will have a larger 2D:4D ratio than males. As well that gender difference (not significant, but existent) results in differing working memory performance and that the 2D:4D ratio with each gender is linked to working memory performance.

Method:

Participants:

The convenience sample used, consisted of 497 undergraduate psychology students at Monash University. 385 female participants and 112 male participants volunteered for the study. Minimum age of 18 and maximum age of 64 (M=23.37 SD= 7.48) .

Materials

An online simulation testing spacial working memory called the N-back test was used to measure the participant’s reaction time and accuracy of their spacial working memory. The task involved remembering where a dot was presented on the screen and then moving it according to where the stimulation indicated, consisting of 10 trials.  The 2D:4D ratio was measured in millimeters using a ruler.

Procedure:

Participants were asked to complete the n-back test in the 10 trials. The online simulation tested the reaction time of participants in milliseconds

They were then instructed to measure the length of their index (2D) and ring (4D) fingers from the bottom creases to the top. The 2D:4D ratio was then calculated by dividing the 2D (length of index finger) by the 4D (length of ring finger) ie. 2D/4D. Participant’s results were then collected voluntarily through their submission of data, after it was approved by the Monash University committee of ethics.

Design:

The study implemented an independent measures, quasi-experimental design to determine whether there was a gender difference in the accuracy and reaction time of spacial working memory as well as the size of the 2D:4D  ratio. The participants were taken from a convenience sample and randomly allocated .

Results:

In order to calculate if gender influenced the 2D:4D ratio and working

memory
performance as well as if the variables of 2D:4D and working memory performance were correlated, the raw data obtained was analyzed and assessed using IBM SPSS version 20. Both independent measures t-test and Pearson’s correlation statistics. Both with an a- level of 0.05 considered to be statistically significant.

Descriptive statistics were obtained for both genders results are available in table 1. The independent samples t-test (table 2) was then used to measure the mean scores of reaction time, accuracy and 2D:4D ratio for both males (n=112)
and females (n=385).