Commenting in the journal Nature Neuroscience, the UCL researchers said the results correspond with common situations involving deception, with everyone from tax-evaders, adulterers and sports cheats often recalling how "small acts of dishonesty snowballed over time".

The same principle "may also apply to escalations in other actions such as risk-taking or violent behaviour," lead author Dr Neil Garrett adds.

Previous studies have suggested that in the brains of psychopaths, the amygdala shows reduced activity in response to graphic images of murder scenes.

Small fibs could turn you into a full-blown liar, study finds