Testosterone and nonverbal intelligence in right-handed men and women.

The relationship between serum testosterone level and nonverbal intelligence was studied in right-handed young adults. Hand preference was assessed by the Edinburgh Handedness Inventory. Serum testosterone level was determined using tritium-marked-radioimmunoassay. Only in men, nonverbal intelligence (Cattell's Culture Fair Intelligence Test) was found to be significantly and directly related to serum testosterone levels. It was concluded that the serum testosterone in young adults is associated with nonverbal intelligence exhibiting fundamental differences between men and women.