Many people passing off expensive items as cheaper ones at self-serve checkouts do not consider the behaviour to be stealing, and try to justify their behaviour, an ANU researcher says.

ANU criminologist Emmeline Taylor reviewed surveys from around the world on the subject, and said some anonymous surveys indicated up to a third of shoppers knowingly manipulated self-serve checkouts.

She said many shoppers tried to rationalise their behaviour.

"Some people do try and justify it to themselves, that y'know these major retailers, they must have such a huge profit margin, what will they notice if I have a five-finger discount?" she said.

"Other people see this as more ideological, they think 'well they're not employing people anymore, I have to transact myself so I should be compensated."

Dr Taylor calls the shoplifters "swipers", or seemingly well-intentioned patrons engaging in routine shoplifting, and said the impersonal nature of mechanical checkouts meant some shoppers found it easier to steal.

"The people who engage in this don't think it's theft, they see it as cheating, because essentially they pay something, so they get a discount," she said.

"Initially it's accidental ... but for some people realising how easy that was - it becomes almost addictive.

"It's a very different behaviour to going into a store and filling your handbag or stuffing goods down your pants and stealing them in that way - that's very deliberate.

"But when you're interacting with a machine and you can convince yourself that you actually didn't mean to steal something, then it's a very different type of behaviour."

Dr Taylor said the problem's prevalence was highlighted by an incident in which a supermarket discovered it was selling more carrots than it had in stock.

"This wasn't that suddenly customers were trying to get more vitamin C, they realised that they were using these heavy root vegetables and passing them off as more expensive items such as cherries and avocados," she said.

Dr Taylor suggested improved customer service, and better technology could help curb the behaviour.