one advocate of greater male variability during this time was the american psychologist edward thorndike, one of the leading exponents of mental testing who played an instrumental role in the development of today's armed services vocational aptitude battery asvab. in his 1906 publication "sex in education", thorndike argued that while mean level sex differences in intellectual ability appeared to be negligible, sex differences in variability were clear . other influential proponents of the hypothesis at this time were psychologists g. stanley hall and james mckeen cattell.. thorndike believed that variability in intelligence could have a biological basis and suggested that this could have important implications for achievement and pedagogy. for example, he postulated that greater male variation could mean "eminence and leadership of the world's affairs of whatever sort will inevitably belong oftener to men" (hollingsworth, 1914, p. 511). in addition, since the number of women that fall within the extreme top-end of the intelligence distribution would be inherently smaller, he suggested that educational resources should be invested in preparing women for roles and occupations that require only a mediocre level of cognitive ability .