Graduate Program

Clinical Psychology

Degree Name

Master of Arts (MA)

Semester of Degree Completion


Thesis Director

Jeffrey R. Stowell


Digit ratio is the difference in length between the pointer finger and the ring finger on either hand. Commonly referred to as the 2D:4D ratio, this ratio is determined prior to birth, and serves as an indicator of prenatal hormone exposure. Digit ratio has been found to correlate with fundamental personality and behavior characteristics in adulthood. Digit ratio is also thought to be a determinate of sexual orientation in both men and women, but has been debated in the literature. This study examined multiple 2D:4D relationships. Men who were found to have a more masculinized (ie. lower) digit ratio had significantly higher rates of overall sensation seeking, boredom susceptibility, disinhibition, experience seeking, and lifetime drug behaviors. We found no significant relationships between 2D:4D ratio and behaviors in females. Similarly, we found no relationship between digit ratio and sensation seeking, impulsive, or risky personality traits either. Digit ratio bad no relationship with sexual orientation, nor on number of older brothers. Overall, our findings suggest that there is a significant relationship between a masculinized digit ratio and certain sensation seeking and risk taking behaviors in men.