Boys and girls ages 8-11 use different portions of their brains to recognize faces and expressions. Boys use more of their right hemisphere while girls use more of their left. (Pease, Barbara and Allan. Why Men Don’t Have a clue and Women Always Need More Shoes. NY: Broadway Books, 2004, pp 261-262)

By four months of age, most baby girls can distinguish photographs of people they know from photographs of strangers. Boys usually cannot. (Moir, Anne, and David Jessel. Brain Sex, the Real Difference Between Men & Women. NY: Carol Publishing Group, 1989, 1991, p 56)