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The Brain that Changes Itself …..6 seconds before you do!

July 22, 2010

Predicting which button you intend to press

I watched an astonishing BBC documentary on the Australian TV Channel SBS a couple of nights ago.

SIX SECONDS before you make a decision to press a button (in the fMRI research condition) your brain registers its intent.

The choices were left button or right button. Sophisticated computer programs were trained to recognize typical brain activity patterns preceding the two choices. A researcher can predict which button you are going to press six seconds (or more) before you actually do it. Count six seconds….that’s a long time ahead! The decision could not be predicted perfectly, but prediction was clearly above chance.

The researchers from the group of Professor John-Dylan Haynes from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, used a brain scanner to investigate what happens in the human brain just before a decision is made.

“Many processes in the brain occur automatically and without involvement of our consciousness. This prevents our mind from being overloaded by simple routine tasks. But when it comes to decisions we tend to assume they are made by our conscious mind. This is questioned by our current findings.” (Nature Neuroscience, April 13th 2008)

Just decide to press the left button or right button

Participants could freely decide if they wanted to press a button with their left or right hand. They were free to make this decision whenever they wanted, but had to remember at which time they felt they had made up their mind.

What happens in the brain? Your choice can be predicted!

The aim of the experiment was to find out what happens in the brain in the period just before the person felt the decision was made. The researchers found that it was possible to predict from brain signals which option participants would take before they consciously made their decision. The fact that decisions can be predicted so long before they are made is an astonishing finding.

Micropatterns of activity in the frontal cortex were predictive of the choices even before participants knew which option they were going to choose. This suggests that the decision is unconsciously prepared ahead of time but, the researchers suggest that the final decision might still be reversible.

“Free will”: our decisions are prepared unconsciously?

Many scientists argued that if our decisions are prepared unconsciously by the brain, then our feeling of “free will” must be an illusion. In this view, it is the brain that makes the decision, not a person’s conscious mind. But they also warn that the study does not finally rule out free will:

“Our study shows that decisions are unconsciously prepared much longer ahead than previously thought. But we do not know yet where the final decision is made. We need to investigate whether a decision prepared by these brain areas can still be reversed.”

Chun Siong Soon, Marcel Brass, Hans-Jochen Heinze & John-Dylan Haynes
Unconscious determinants of free decisions in the human brain.
Nature Neuroscience April 13th, 2008.

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