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

Kim, Hye Jin; Lee, Woo Kyeong; Kim, Suno; Lee, Sang Baek; Park, Jae Woo; Lee, Yu Sang

Abstract

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.