In one of three studies, Pia Rosander carried out personality tests on 200 pupils in southern Sweden when they entered upper secondary school at 16. Three years later, when they received their final grades, she was able to observe a strong link between personality and grades.

In personality psychology one talks of "the big five" - the five most common personality traits: openness, conscientiousness, extraversion, agreeableness and neuroticism. These qualities influence how a person behaves and are relatively stable qualities, which means that they do not change greatly over time or in different situations.

One of the traits is clearly associated with high grades: Neuroticism, where pupils are driven by fear and worry, also led to high grades. Contrary to Pia Rosander's hypothesis, openness, or intellectual curiosity, did not lead to high grades.

"We have a school system in Sweden that favours conscientious and fear-driven pupils", says Pia Rosander. "It is not good for psychological well-being in the long term if fear is a driving force. It also prevents in-depth learning, which happens best among the open personality types who are driven by curiosity."

Today's school system therefore favours girls who are eager to please. Boys are more likely to have the personality types that area driven by interest and curiosity and do not benefit from the Swedish system of grades. For the girls, there was a link between high IQ and conscientiousness. Surprisingly, for boys, the opposite was the case - the conscientious boys often had a lower IQ than those who were less conscientious.

"Greater conscientiousness, i.e. getting things done, arriving on time, etc. may be a way for boys to compensate for a lower IQ", says Pia Rosander, who thinks her results should make teachers reflect on the grounds used to set grades.

Other surprising results from the study are that introverted personality types get higher grades than extroverted types. Pia Rosander assumes this is because extroverted personality types have so many other things to focus on that they have difficulty making time for school work.

"My studies clearly show that the school system needs to be more individualised", says Pia Rosander. "How else can we support talented pupils with the 'wrong' personality type, those we call under-performers, who are capable but lack the ability to plan their school work, for example?"

In Pia Rosander's view, school teachers must realise that personality is something that neither pupils nor teachers and parents can influence. She believes that telling careless pupils off and instructing them to get their act together doesn't help. Instead, such pupils must be given help with structure and study techniques.