January 5, 2016

Berlin researchers test mechanisms involved in decision-making

Duel against the computer: a participant during the Experiment,
Copyright: Charité, Carsten Bogler

(January 5, 2015)  Our choices seem to be freer than previously thought. Using computer-based brain experiments, researchers from Charité – Universitätsmedizin Berlin studied the decision-making processes involved in voluntary movements. The question was: Is it possible for people to cancel a movement once the brain has started preparing it? The conclusion the researchers reached was: Yes, up to a certain point – the 'point of no return'. The results of this study have been published in the journal PNAS.

The background to this new set of experiments lies in the debate regarding conscious will and determinism in human decision-making, which has attracted researchers, psychologists, philosophers and the general public, and which has been ongoing since at least the 1980s. Back then, the American researcher Benjamin Libet studied the nature of cerebral processes of study participants during conscious decision-making. He demonstrated that conscious decisions were initiated by unconscious brain processes, and that a wave of brain activity referred to as a 'readiness potential' could be recorded even before the subject had made a conscious decision.

How can the unconscious brain processes possibly know in advance what decision a person is going to make at a time when they are not yet sure themselves? Until now, the existence of such preparatory brain processes has been regarded as evidence of 'determinism', according to which free will is nothing but an illusion, meaning our decisions are initiated by unconscious brain processes, and not by our 'conscious self'. In conjunction with Prof. Dr. Benjamin Blankertz and Matthias Schultze-Kraft from Technische Universität Berlin, a team of researchers from Charité's Bernstein Center for Computational Neuroscience, led by Prof. Dr. John-Dylan Haynes, has now taken a fresh look at this issue. Using state-of-the-art measurement techniques, the researchers tested whether people are able to stop planned movements once the readiness potential for a movement has been triggered.

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