POLITICSmugs for money. The mug owners were told to set a price they would
accept, and the mug buyers were told to set a price they would pay. The
mug owners asked for an average of $5.78, and the mug buyers offered
an average of $2.21. The sellers were reluctant to part with their mugs.
The buyers were reluctant to part with their money. Both buyers and
sellers were reluctant to give up what they had.
The essential role of the amygdala in loss aversion was confirmed
by something called an experiment of nature. Experiments of nature
are illnesses and injuries that reveal important pieces of scientific
knowledge. They are fascinating because they usually represent “exper-
iments” that would be grossly unethical for a scientist to carry out. No
one’s going to ask a surgeon to open up a person’s head and cut out
their amygdala. But once in a while it happens on its own. In this case,
scientists studied two patients who had Urbach–Wiethe disease, a rare
condition that destroys the amygdala on both sides of the brain. When
these individuals were presented with wagers, they attached equal
weight to gain and loss. Without the amygdala, loss aversion vanished.
In a way, loss aversion is simple arithmetic. Gain is about a better
future, so only dopamine is involved. The possibility of gain gets a +1
from dopamine. It gets zero from H&N, because H&N is only con-
cerned with the present. Loss is also about the future, so it concerns
dopamine, and gets a –1. Loss concerns H&N, too, because it affects
things in our possession right now. So H&N gives it a –1. Put them
together, and gain = +1, loss = –2, exactly what we see with the brain
scans and the wagering experiments.
Fear, like desire, is primarily a future concept—dopamine’s realm.
But the H&N system gives a boost to the pain of loss in the form of
amygdala activation, tipping our judgment when we have to make deci-
sions about the best way to manage risk.
TO PROVIDE OR PROTECT?Although loss aversion is a universal phenomenon, there are differences
among groups. Overall, dopaminergic liberals are more likely to respond