The Relationship between 2nd Digit/4th Digit Ratio and Empathy, Aggression, and Sex Role in College Students / 신경정신의학

OBJECTIVES: The study investigated the role of prenatal testosterone on the development of sexually dimorphic psychological phenotype. Finger length ratio (2nd digit/ 4th digit, 2D/4D), especially on the right hand, is thought to be influenced by prenatal exposure to testosterone. We evaluated the relationship between 2D/4D and psychological characteristics in college students. METHODS: Participants were 137 college students who completed 3 self-report measures : the Emotional Empathy Scale, Aggression Scale, and Bem Sex Role Inventory (BSRI). After copying right ventral surface of the participant's hand, we measured the lengths of the 2nd and 4th fingers, from basal crease to tip, using vernier calipers. We performed statistical analyses using correlation tests and t-tests to examine the relationship between 2D/4D and psychological characteristics (empathy, aggression, and sex role) RESULTS: We observed significant correlations between sex differences and average 2D/4D ratio. Men had a lower 2D/4D ratio than women, confirming the typical sex difference in digit proportions. In women, there was a significant correlation between 2D/4D ratio and empathy. Women with higher, more feminine, finger length ratios had higher empathy scores. We found no correlation between 2D/4D and aggression or sex role. CONCLUSION: There was a positive correlation between 2D/4D and empathy, but in women only. Low prenatal testosterone might play important role in the development of an essential, typically feminine, psychological phenotype (empathy), in women.

The Correlation between 2nd to 4th Digit Length Ratio and Characteristics of Temperament and Character in University Students

OBJECTIVES: The 2nd to 4th digit length(2D:4D) ratio reflects the amount of exposure and sensitivity to the prenatal sex hormone and it is considered to be the most convenient and useful way to understand the influence of sex hormone in the determination of human behavioral traits. This study was carried out to find the correlation between the 2D:4D ratio and characteristics of temperament and character in Korean university students. We assumed that 2D:4D ratio would show a strong correlation with temperament which is defined to be an inclination of an automatical emotional response to a stimulus. METHODS: Participants were 104 university students who completed 2 self-report measures:Temperament and Character Inventory(TCI), Temperament Test. We examined the 2D:4D ratio of each subject by measuring the lengths of the 2nd and 4th fingers using a photocopy measurement. We performed statistical analyses using correlation test and t-test to examine the relationship between 2D:4D ratio and psychological characteristics. RESULTS: We found out the typical sex difference in 2D:4D ratio. Women had significantly higher 2D:4D ratio than men. TCI-Character factor(TCI-C) didn't show any significant correlation with the 2D:4D ratio. TCI-Tempterament factor(TCI-T) and the item of Temperament Test showed a significant correlation with the 2D:4D ratio. In correlation analysis of the total group including all women and men, the 2D:4D ratio showed a significant positive correlation in a subscale(shyness with stranger) of harm avoidance scales in TCI-T. In correlation analysis of women's group, the 2D:4D ratio showed a significant positive correlation in two subscales( fear of uncertainty) and[shyness to stranger] of harm avoidance scales in TCI-T. In correlation analysis of men's group, the 2D:4D ratio showed a significant negative correlation with a sanguine temperament item of the Temperament Test. CONCLUSION: The results suggest that the amount of exposure to sex hormone in the prenatal period seems to have an impact on the determination of temperament and characteristics.