it has been noted by researchers that, "children as young as 18 months display sex-stereotyped toy choices". when eye movement is tracked in young infants, infant girls show a visual preference for a doll over a toy truck (d > 1.0). boys showed no preference for the truck over the doll. however, they did fixate on the truck more than the girls (d = .78). this small study suggests that even before any self-awareness of gender identity has emerged, children already prefer sex-typical toys. these differences in toy choice are well established within the child by the age of three.