Little fibs to outright lies.
LITTLE white lies are the thin edge of a wedge leading to whoppers as the brain gets used to fibbing, research shows.
A moral "policeman" in the brain called the amygdala becomes increasingly likely to look the other way the more we lie as its warning goes unheeded by, the study suggests.
Scientists believe the same principle might also explain how violence can escalate, leading to horrific crimes or a willingness to inflict torture.
Experimental psychologist Dr Tali Sharot, a member of the University College London (UCL) team, said: "When we lie for personal gain, our amygdala produces a negative feeling that limits the extent to which we are prepared to lie. However, this response fades as we continue to lie, and the more it falls the bigger our lies become. This may lead to a 'slippery slope' where small acts of dishonesty escalate."
Lead author Dr Neil Garrett, also from UCL, said it was likely the findings reflected a blunted emotional response to lying. He added: "This is in line with suggestions that our amygdala signals aversion to acts that we consider wrong or immoral."