Small lies are a slippery slope, study finds

Tell a small lie too many times and soon enough you'll find yourself telling bigger lies, a new study suggests. Not only that, but you'll find it easier to tell the bigger lies as your brain adapts to being dishonest. Allowed to continue unhampered, these scenarios are likely to eventually lead to the kind of big lies that can ruin careers and destroy marriages.

The study cites "self-serving" lies specifically, meaning a lie that ultimately benefits yourself by means of dishonesty — telling a small lie about work experience to land a job, perhaps, lying about income to fit into a particular social group, and other things. As many people know, small lies like these have a way of snowballing, not just in the sense that other lies may need to be told to cover them up, but also the ease by which other new, and usually larger, lies are told.

This slow, steady growing of dishonesty has a biological underpinning, according to the study — one's brain adapts to the lies over time, becoming desensitized to small lies so that slightly bigger ones are less difficult. This desensitization process continues with the larger lies, paving the way for even larger ones. Humans have reduced amygdala sensitivity to thank for that.

The researchers go on to say that "the extent of reduced amygdala sensitivity to dishonesty on a present decision relative to the previous one predicts the magnitude of escalation of self-serving dishonest on the next decision."

Interestingly enough, though, this escalation of dishonesty is not observed when lies are told for the benefit of a 'partner.' If, for example, your best friend asks if you think their baby is cute and you don't think it is, you'll probably say yes regardless for your friend's benefit.

Such scenarios aren't just the plot lines of various Seinfeld episodes, and indeed in some cases are considered a social expectation, as the lie is perceived a lesser transgression than, for example, hurting someone's feelings. In this case, where the benefit is solely for the partner, desensitization and the resulting escalation weren't readily observed.