Effects of sex hormones on cognitive style in rats and men.

Abstract

This paper presents both a review of empirical studies regarding the interacting effects of sex hormones and socialization on cognitive style in rats and men and a new experimental study of the effects of sex hormones on the white rat. In a study of West African males feminized by a kwashiorkor-induced endocrine dysfunction, it was found that males presenting the gynecomastia symptom had a significantly more feminine cognitive style than control males—the former subjects having lower spatial ability, being more field dependent, with higher verbal and lower numerical ability, and having significantly more feminine scores on two measures of sexual bias than the controls. Evidence is also presented to show that in cases of testicular feminization, Turner's syndrome, and Klinefelter's syndrome—even where the sex of rearing is opposite to the genetic sex—the subjects develop cognitive abilities in line with sex of rearing and socialization. The hypothesis is formed as a result of these studies that, while masculine behavior is probably differentiated in the brain by male hormones neonatally, this process is susceptible to both estrogen feminization and dominant female socialization influences. As there is also considerable evidence to show that normal male rats have higher spatial ability than female rats (who have higher activity levels), it was decided to test this hypothesis by establishing an initial sex difference in spatial learning in white rats and then to attempt to reverse it by administering estrogen and testosterone to male and female rats. A significant sex difference in spatial learning was initially established on the Tolman maze. No significant changes were found in the estrogen-treated males after the first estrogen implant, but a significant change toward the female mean was obtained after the second. There were no significant changes for the testosterone-treated females. It is suggested that future studies should make use of male and female rats feminized and masculinized at birth to ensure adequate programming of the brain of opposite sex behavior. It is also pointed out that maze- and geometric-type measures of intelligence for rats and men are not truly representative of the major sex-based abilities, as they require a certain level of spatial ability for solution and hence favor males. It is further observed that spatial ability in males has been biologically adaptive in evolution—which would help to explain the physiological basis of sex hormone differences with respect to masculine and feminine cognitive styles.