Betting
on the toss is something most of us have done at one time or another, even it
is as harmless as deciding who should start first in some game or other. Our
logic tells us that heads or tails is a 50:50 chance. Of course, logic
sometimes goes out the window.
If
we repeatedly toss a coin and we get a run of heads or tails, our logic weakens
and we misquote the law of averages and bet against the run, even though in
calmer moments we know that the chance of that last coin toss is still 50:50
for heads or tails.
This
poor judgment is known as the gambler’s fallacy and is very difficult to resist
if the run is a long one. In order to see where in our brains we work so hard
to make silly decisions, Xue et al
has used fMRI scans with a card choice game and have published their data in
the Proceedings of the National Academy of Science (1).
The
choice was to guess the color of a black or white card so, like coin tossing,
each choice had a 50:50 chance. However, the gambler’s fallacy is alive and
well and the subjects made bad decisions when there was a run of one color so
over the long run, they did rather worse than the 50% correct that would always
be approached with enough turns.
The
interesting new bit of information is that there was a rush of oxygenated blood
to the heads of the subjects about 10 seconds before letting their instinct
over-ride their better judgment. To be precise, the blood oxygen levels in the
left lateral prefrontal cortex were elevated.
Now
remember that the prefrontal cortex is where our emotional responses are
buzzing around and that the dopamine and serotonin receptors are making us feel
good so its not surprising that our logic can slip a little. If the region was
externally stimulated electrically, the bad decisions on card choice were
exacerbated.
Would
holding our breath before making decisions help, I wonder or would that be
counter productive by subsequently increasing our heart rate? Perhaps it’s
better to avoid such excitement altogether.
- G. Xue, C-H. Juan, C-F. Chang Z-L. Lu and Q. Dong, Proc. Nat. Academy. Sci., (2012). doi:10.1073/pnas.1111927109
