Final answer:
The study found that 2-year-olds with high levels of gender knowledge didn't display a preference for gender-neutral toys.
Step-by-step explanation:
The subject of this question is Psychology and it pertains to the study of gender roles and the influence of gender knowledge on toy preferences in 2-year-olds.
According to the information provided, the study by Campbell et al found that 2-year-olds who possessed high levels of gender knowledge didn't display a preference for gender-neutral toys. This means that these children did not choose toys that were typically associated with the opposite gender. Instead, they were more likely to choose toys that were considered gender appropriate for their own gender, such as gender-stereotyped toys like trucks for boys or dolls for girls. However, the study did not find a preference for gender-stereotyped toys, their own gender's clothing, or playing with children of the opposite gender.