Men who physically abuse their partners overestimate how often such violence occurs, which helps them justify their own actions, according to a new study.

University of Washington researchers looked at 124 men enrolled in a larger study of treatment intervention for domestic violence. The men, who had committed violence against a partner in the previous 90 days, were asked to estimate the percentage of men who had ever engaged in seven forms of abuse: throwing something at a partner that could cause injury; pushing, grabbing or shoving a partner; slapping or hitting; choking; beating up a partner; threatening a partner with a gun; or forcing a partner to have sex against their will.

The men overestimated by two to three times the actual rates of the seven forms of abuse. For example, the participants on average believed that about 28 per cent of men had thrown something with the intent of hurting a partner, but the actual rate in the United States is around 12 per cent. The men also believed that close to 24 per cent of men had forced a partner to have sex, compared to the actual rate of near 8 per cent.

The study is published in the April issue of the journal Violence Against Women.

'We don't know why men make these overestimations, but there are a couple of likely reasons,' lead author Clayton Neighbours said in a news release. 'Men who engage in violent behaviour justify it in their mind by thinking it is more common and saying, 'Most guys slap their women around so it is OK to engage in it.' Or it could be that misperceptions about violence cause the behaviour,'

'Another way of looking at this would be wearing a red shirt. If you think everyone is wearing a red shirt then it is okay for you to wear one too. Or if you wear a red shirt you might overestimate the number of other people who are wearing red shirts,' said Neighbours, a UW affiliate professor of psychiatry and behavioral sciences and a professor of psychology at the University of Houston.

'The more we can correct misconceptions about the prevalence of intimate partner violence, we have a chance to change men's behaviour. If you give them factual information, it is harder for them to justify their behaviour,' he added.