by Tanya Lewis
Some people are just manipulative jerks.
They deceive people for their own benefit, they see others as weak and untrustworthy, and they ignore moral codes.Psychologists have dubbed these people Machiavellians, after the Italian political philosopher Niccolo Machiavelli, whose book "The Prince" includes many examples of this sort of unsavory character.
Now, a recent study published in the journal Brain and Cognition reveals what goes on in the brains of these social deviants when they're around others who are acting fairly.
Machiavellianism — which is part of the "dark triad" of personality traits, along with narcissism and psychopathy — falls on a spectrum, from low Machs (aka normal people) to high Machs (aka jerks).
Tamas Bereczkei and his
colleagues at the University of Pecs in Hungary gave 38 university
students (20 men and 18 women) a 20-item questionnaire consisting of
short statements about the rules and principles involved in
relationships with others. People who scored less than or equal to 88
were defined as low Machs, while those who scored greater than or equal
to 114 were defined as high Machs. (You can take a similar test yourself
here, but it's on a different scale.)
Twenty-two of the students scored as low Machs and 16 were high Machs.
The trust game
The students played a
two-round trust game while their brains were scanned by an MRI machine.
The machine measures the amount of blood flowing to different parts of
the brain, which corresponds to which parts are most active at one time.
In the first round, a student
was given a small sum of real money and allowed to "invest" some portion
of it in a trustee (which was actually a computer algorithm). The
trustee then returned some of that money to the investor.
In the second round, the
investor became the trustee, and vice versa. Now, the student received
an investment, and had the choice of how much to give back to the
investor.
An offer was considered "fair"
if the return was the same amount as the first player's offer, give or
take 10%. An unfair offer returned only 30% of the original offer, give
or take 10%.
When the high Machs received a
fair offer in the first round, they returned an unfair offer, whereas
the low Machs returned fair offers with fair offers of their own.
What a selfish brain looks like
High Machs exhibited higher
brain activity in certain areas when their partner made a fair return
offer, as opposed to an unfair offer.
Specifically, they had increased
activity in two parts of their brain: The anterior dorsolateral
prefrontal cortex, a region thought to be involved in suppressing
emotional responses, and the inferior frontal gyrus, an area responsible
for evaluating social behavior and cooperation, as shown below.
Those who scored high on
the Machiavellian scale also earned more money in the game than their
less manipulative colleagues, the researchers found.
The researchers think the reason
the high Machs has these spikes in brain activity was because they had
to use more mental energy to respond to their partner's cooperative
behavior (in order to take advantage of it).
These findings agree with previous studies that show Machiavellians act in their own self-interest and manipulate others for personal gain.
Future studies will be needed to
understand how Machiavellians control their emotions and what brain
structures are involved in their cold and calculating behavior, the
researchers reported.
