For the individual, gender difference falls along the feminine-masculine continuum with strong neurodevelopmental influences at various points throughout the lifespan. Neurodevelopmental influences are conceptualized in a vector model of sex difference. Vector attributes, direction and magnitude, are influenced initially by differences in levels of sex hormones at developmentally sensitive points in the lifespan. Hormonally induced variation is secondarily reinforced by sex role influences of society and culture. A hormonally induced and culturally reinforced vector model of sex differences is adequate to account for the large range of variation in cognitive and learning patterns of individuals within female and male populations, as well as the mean difference between the gender groups. (Author)