Only three in five drivers who use a handheld phone behind the wheel say that causing an accident would make them stop for good, according to research for the RAC's Be Phone Smart campaign.
The RAC said it was surprised the figure was not significantly higher given that the consequences can be so severe in terms of the impact on human life.
Motorists were asked what would make them permanently stop using a handheld phone while driving.
Being responsible for causing an accident came top (60%), followed by being caught or the threat of being caught by a police officer (55% and 54% respectively), knowing the victim of an accident where handheld phone use was a factor (54%), and causing a near-miss (53%).
The findings suggest that a sizeable minority of drivers don't understand how distracting using a handheld phone at the wheel can be, and believe they are not likely to cause an accident or be stopped by the police.
Pete Williams, spokesman for the RAC's Be Phone Smart campaign, said: "It seems reasonable to expect that causing an accident while using a handheld phone would be enough to force every driver to change their ways. But our data suggests otherwise -- while six in 10 motorists told us they thought that would motivate them to kick the illegal habit, that indicates a remarkable four in 10 didn't think it would."
This week, police across the UK launched a crackdown on motorists using their mobile phones while driving.
The week-long campaign will remind drivers of the dangers of using a phone behind the wheel and the penalties for doing so. There will be an increase in traffic operations during the week.
Following a change in the law in March, motorists caught using a mobile while driving receive six points on their licence and a £200 fine.