Variability Hypothesis

1914

Leta Stetter Hollingworth (1886–1939)

A commonly held belief originating early in the nineteeenth century, the variability hypothesis states that men exhibit greater variability than women across both mental and physical traits. For example, it was commonly believed throughout the nineteenth and early twentieth centuries that men varied more than women in their intellectual ability, thus occupying more of both the upper and lower ends of the intelligence spectrum. Since women were less variable, they were also doomed to mediocrity; only men could attain genius. Charles Darwin’s theory of evolution by natural selection buttressed this conviction in male superiority. Since evolutionary progress was dependent on a healthy pool of genetic variability, the greater variability of the males of the species was seen as desirable. Although empirically unsupported, this belief was used by many social scientists to justify educational and occupational restrictions for women. The variability hypothesis was not seriously challenged until the work of psychologist Leta Stetter Hollingworth, who in 1914 published an extensive review of the literature that debunked the notion of greater variability in males.

Hollingworth carried out a large-scale study of one thousand male and one thousand female infants at the New York Infirmary for Women and Children. She found that while males were slightly larger physically than females, anatomical variability actually favored the females. She also conducted a systematic review of the literature and found no evidence to support the hypothesis for female intellectual inferiority. Finally, she reasoned that even if the scores of males were more variable than those of females on tests of mental traits, this alone would not prove that greater variability was innate, since men and women experienced entirely different environments and social expectations. Although Hollingworth’s research led to a rejection of the variability hypothesis, the idea occasionally receives attention from research psychologists to this day.

SEE ALSO On the Origin of Species (1859), Sex Roles (1944)

“Where there’s smoke there’s fire,” a 1920s illustration by American artist Russell Patterson (1893–1977) of a fashionably dressed flapper—a “new breed” of woman who flouted social and sexual norms during the Roaring Twenties.