Scientific American Mind-June/July 2007

(perspectives)
Betting on Consciousness
Gambling may offer a way to test conscious awareness without disturbing it
BY CHRISTOF KOCH AND KERSTIN PREUSCHOFF
MUCH OF WHAT we do goes on outside
the pale of consciousness: whether
we adjust our body posture or decide
to marry someone, we often have
no idea why or how we do the things
we do. The Freudian notion that most
of our mental life is unconscious is diffi
cult to establish rigorously. Although
it seems easy to answer the question
“Did you (consciously) see the light
turn on?” more than 100 years of research
have shown otherwise. The key
problem is defining consciousness
such that one can measure it independently
of the internal state of an individual’s
brain while still capturing its
subjective character.
One common experimental assessment
of consciousness—or awareness
of sensation, perception or thought—
is based on “confi dence.” For instance,
a subject has to judge whether a cloud
of dots on a computer screen moves to
the left or to the right. He then reports
how confident he is by assigning a
number—for example, 1 to indicate
pure guessing, 2 for some hesitation
and 3 for complete certainty. This procedure
assumes that when the subject
has little awareness of the dots’ direction
of motion his confi dence is low,
whereas if he clearly “saw” the motion
his confi dence is high.
The Money Question
Now a report by Navindra Persaud
of the University of Toronto and Peter
McLeod and Alan Cowey of the University
of Oxford introduces a more
objective measure of consciousness: it
exploits people’s desire to make money.
This method was adapted from
economics, where it is used to probe a
subject’s belief about an event’s likely
outcome. People who know that they
have information are willing to bet on
it. That is, they are willing to put their
money where their mouth is. Think of
investing in mutual funds. The more
certain you are that high technology
will do well over the next year, the
more money you will allocate to a
technology-sector fund.
Persaud and his colleagues use this
kind of wagering to reveal consciousness
or lack thereof. In their experiments,
subjects do not state their confidence
in their awareness directly.
Instead they fi rst make a decision re-
( The Freudian notion that most of our mental life is unconscious )
is diffi cult to establish rigorously.
16 SCIENTIFIC AMERICAN MIND June/July 2007
COPYRIGHT 2007 SCIENTIFIC AMERICAN, INC.
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