Unconscious brain ”makes the best decisions”

December 25th, 2008 - 1:18 pm ICT by ANI  

Washington, Dec 25 (ANI): People are likely to make optimal decisions when their unconscious brain makes the choice, according to a new study from University of Rochester.
The researchers have found that human brain is actually hard-wired to make the best decisions possible with the information we are given.
“A lot of the early work in this field was on conscious decision making, but most of the decisions you make aren”t based on conscious reasoning,” said Pouget.
“You don”t consciously decide to stop at a red light or steer around an obstacle in the road. Once we started looking at the decisions our brains make without our knowledge, we found that they almost always reach the right decision, given the information they had to work with,” he added. Pouget has been demonstrating for years that certain aspects of human cognition are carried out with surprising accuracy.
For the study, he employed a very simple unconscious-decision test. A series of dots appears on a computer screen, most of which are moving in random directions.
A controlled number of these dots are purposely moving uniformly in the same direction, and the test subject simply has to say whether he believes those dots are moving to the left or right.
The longer the subject watches the dots, the more evidence he accumulates and the more sure he becomes of the dots” motion.
The subjects performed exactly as if their brains were subconsciously gathering information before reaching a confidence threshold, which was then reported to the conscious mind as a definite, sure answer.
The subjects, however, were never aware of the complex computations going on, instead they simply “realized” suddenly that the dots were moving in one direction or another.
Pouget also analysed the data from a test performed in the laboratory of Michael Shadlen, a professor of physiology and biophysics at the University of Washington.
Shadlen’’s team watched the activity of a pair of neurons that normally respond to the sight of things moving to the left or right. For instance, when the test consisted of a few dots moving to the right within the jumble of other random dots, the neuron coding for “rightward movement” would occasionally fire.
As the test continued, the neuron would fire more and more frequently until it reached a certain threshold, triggering a flurry of activity in the brain and a response from the subject of “rightward.”
Pouget said a probabilistic decision-making system like this has several advantages. The most important is that it allows us to reach a reasonable decision reasonable amount of time. If we had to wait until we”re 99 percent sure before we make a decision, Pouget says, then we would waste time accumulating data unnecessarily.
If we only required a 51 percent certainty, then we might reach a decision before enough data has been collected.
The study appears in journal Neuron. (ANI)

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