BOYS' eagerness to appear hard and macho prevents them achieving, say secondary-school pupils - including the boys themselves.
Three-quarters of pupils of both sexes think boys are their own worst enemy when it comes to learning, University of Greenwich researchers found.
One hundred pupils from three London schools were asked if they agreed with comments made by former education minister Stephen Byers that laddish behaviour impeded boys' learning.
It was last year that Mr Byers declared war on the "laddish anti-learning culture" which held boys back in the classroom. Local authorities were ordered to address boys' underachievement in their development plans.
Almost 70 per cent of pupils agreed with Mr Byers' comments. Many of the quarter who disagreed said "laddism" could be true of some, if not all, boys.
Older boys were more likely than younger boys to agree. There were also significant racial differences - white boys and African-Caribbean girls were most likely to concur.
Boys cited many reasons for their negative attitudes to learning, such as wanting to impres girls, not liking to be seen as soft or not being mature enough to "capitalise on the opportunity" offered by school.
"If your all mates are in the class you can't help messing about. If your mates are not in the class, it's a different matter," said one 16-year-old boy.
However, the girls who were interviewed largely blamed boys' immaturity. "They don't grow up as quick, they should still be in Year 8 because hardly any of them get on with their work," said one 15-year-old girl.
Dr Becky Francis, who conducted the study, said: "Boys seem to be saying that they are their own worst enemy and that an immense pressure on them to be macho is interfering with their learning. What we should be doing is not changing learning materials or teaching styles, but rather the culture of masculinity that belittles learning."