In the study, directed by the Complutense University of Madrid, they interviewed 149 children between 4 and 9 years of age and asked about professions or female and male characteristics, among other issues. They clearly saw that traditional roles were well learned by the younger ones and that their prejudices towards others were conditioned by these roles. By the age of 4, gender stereotypes have already been internalized, but the research did not lead younger children to question them.

According to the study, these gender roles affect the child's psychological development and vocations. Boys and girls use the categories of woman and man to judge others, to choose their playmates, to build their own identity, or to decide what they like.