The study said children’s beliefs could become a “self-fulfilling prophecy” and influence their achievement in the classroom.

Teachers were warned against employing stereotypical language or separating classes into “boys v girls” to avoid adding to children’s preconceived ideas about the gender divide.

The disclosure follows the publication of figures last week showing that boys are falling behind girls at the age of seven.

Data published by the Department for Education showed that 24 per cent of boys in England failed to reach the standard expected of their age group in writing compared with just 13 per cent of girls.

In recent years, the gap has widened throughout primary and secondary education, with girls far more likely to gain good GCSE and A-level results in their teens.

But a report by Kent University suggests that attainment may be linked to girls’ and boys’ own perceptions of their abilities at a very young age.

The study – being presented to the British Educational Research Association annual conference at Warwick University today – presented pupils aged four to 10 with a series of statements such as “this child is really clever” and “this child always finishes their work” and asked them to link the words to pictures of boys or girls.