Girls feel the need to play down on their intelligence to not intimidate boys, according to a new research.
The research, conducted by Dr Maria do Mar Pereira from the University of Warwick's Department of Sociology, found that boys aged 14 had acquired the belief that girls their age should be less intelligent.
"There are very strong pressures in society that dictate what is a proper man and a proper woman. Young people try to adapt their behaviour according to these pressures to fit into society," said Pereira.
"One of the pressures is that young men must be more dominant - cleverer, stronger, taller, funnier - than young women, and that being in a relationship with a woman who is more intelligent will undermine their masculinity," she said.
To conduct the research Pereira spent, with permission of the school and relevant authorities, three months as a student in a Year Eight class observing the everyday lives of school children.
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In order to gain as much insight as possible, she participated in all aspects of their day at school: she attended classes, did Physical education (PE) lessons, took exams, had lunch in the cafeteria, played in the playground and joined them in trips to shopping centres after school.
As a result, she was able to observe aspects of young people's interactions, feelings and behaviours that teachers and parents are often unable to access.
"Our ideas of what constitutes a real man or woman are not natural; they are restrictive norms that are harmful to children of both genders," Pereira said.
"The belief that men have to be dominant over women makes boys feel constantly anxious and under pressure to prove their power - namely by fighting, drinking, sexually harassing, refusing to ask for help, and repressing their emotions.
"Girls feel they must downplay their own abilities, pretending to be less intelligent than they actually are, not speaking out against harassment, and withdrawing from hobbies, sports and activities that might seem 'unfeminine'," she said.