2007-11-23 06:58:50
On receiving a paypacket, how good a man feels depends on how much his
colleague earns in comparison, scientists say.
Scans reveal that being paid more than a co-worker stimulates the "reward
centre" in the male brain.
Traditional economic theory assumes the only important factor is the absolute
size of the reward.
But researchers in the journal Science have shown the relative size of one's
earnings play a major role.
In the study, 38 pairs of male volunteers were asked to perform the same simple
task simultaneously, and promised payment for success.
Both "players" were asked to estimate the number of dots appearing on a screen.
Providing the right answer earned a real financial reward between 30 ( 22) and
120 ( 86) euros. Each of the participants was told how their partners had
performed and how much they were paid.
'Brain scan'
Using magnetic resonance tomographs, the researchers examined the volunteers'
blood circulation throughout the activities. High blood flow indicated that the
nerve cells in the respective part of the brain were particularly active.
Neuroscientist Dr Bernd Weber explains: "One area in particular, the ventral
striatum, is the region where part of what we call the 'reward system' is
located. In this area, we observed an activation when the player completed his
task correctly."
A wrong answer, and no payment, resulted in a reduction in blood flow to the
"reward region". But the area "lit up" when volunteers earned money, and
interestingly showed far more activity if a player received more than his
partner.
This indicated that stimulation of the reward centre was not merely linked to
individual success, but to the success of others.
While behavioural experiments have suggested relative rewards may play a role
in economic motivation, economist Professor Dr Armin Falk, co-author of the
paper, said: "It is the first time this hypothesis has been challenged using
such an experimental approach."
The professor emphasised to BBC News, that unlike behavioural experiments,
brain scans had "no cognitive filter; we were monitoring immediate brain
reaction".