The Fascinating Reason Why
Liars Keep On Lying
Oct. 24, 2016
Scientists can now explain why lying begets more lying
— it has to do with how the brain reacts to fibs
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Once a liar,
always a liar, the old saying goes. Turns out there’s some scientific truth to
that: researchers have tracked down how the brain makes lying easier as the
untruths build up, providing some biological evidence for why small lies often
balloon into ever larger ones.
In a study
published in Nature Neuroscience, Tali Sharot from the department of
experimental psychology at University College London and her colleagues devised
a clever study to test people’s dishonest tendencies while scanning their
brains in an fMRI machine. The 80 people in the study were shown pennies in a
glass jar and given different incentives to guide whether they lied or told the
truth to a fellow partner about how much money was contained in the jar. In
some conditions, both the participant and the partner benefited if the
participant lied; in others, just the participant benefited from his fib, or
just the partner benefited (with no cost to either). In another set of
scenarios, either the participant or partner benefited, but at the expense of
the other if the participant lied. In each case, Sharot documented the changes
in the people’s brains as they made their decisions.
They found that
when people were dishonest, activity in a part of the brain called the
amygdala—the hub of emotional processing and arousal—changed. With each
scenario, the more dishonestly the participant advised his partner, the less
activated the amygdala was on the fMRI. That may be because lying triggers emotional
arousal and activates the amygdala, but with each additional lie, the arousal
and conflict of telling an untruth diminishes, making it easier to lie.
Sharot also
found that the amygdala became less active mostly when people lied to benefit
themselves. In other words, self-interest seems to fuel dishonesty.
“Part of the
emotional arousal we see when people lie is because of the conflict between how
people see themselves and their actions,” Sharot said during a briefing
discussing the results. “So I lie for self-benefit, but at the same time it
doesn’t fit the way I want to view myself, which is as an honest person. It’s
possible that we learn from the arousal signal…with less emotional arousal,
perhaps I’m less likely to see the act as incongruent with my own self
perception.”
The researchers
were even able to map out how each lie led to less amygdala activation and
found that the decrease could predict how much the person’s dishonesty would
escalate in the next trial. Biology seems to back up the warnings parents give
to their kids: that one lie just leads to another.
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