Clever children are saving themselves from being branded swots at school by dumbing down and deliberately falling behind, a study has shown.

Schoolchildren regarded as boffins may be attacked and shunned by their peers, according to Becky Francis, professor of education at Roehampton University, who carried out a study of academically gifted 12- and 13-year-olds in nine state secondary schools.

The study, to be published in the Sociological Review next year, shows how difficult it is for children, particularly boys, to be clever and popular. Boys risk being assaulted in some schools for being high-achievers. To conform and escape alienation, clever boys told researchers they may "try to fall behind" or "dumb down".

One boy told researchers: "It is harder to be popular and intelligent. If the subject comes naturally ... then I think it makes it easier. But if the subject doesn't come naturally, they work hard and other people see that and then you get the name-calling." This may in part explain boys' perceived underachievement, Francis said.

Clever girls, meanwhile, can be seen as less attractive and less popular in some schools than girls who manage average grades.

One girl told the researchers: "My friends are all really nice people and have [a] really good sense of humour, and they're all really pretty and stuff, but because they do well in school they're not popular." But clever girls were, on the whole, under less pressure to fall behind deliberately.

What counts as a swot varies from school to school, but the threshold for what is constituted "boffin behaviour" tended to be lower at poorer-performing schools.

• This article was amended on Monday 30 March 2009. The study we refer to has not been published yet; it is due for publication next year. This has been corrected.