The FIRSTS: brain active before conscious intent (1983)

Actor Jim Carry pretending to be attacked by its own hand in the movie Liar Liar. Dir. Tom Shadyac. Universal Pictures, 1997.
Actor Jim Carrey pretending to be attacked by its own hand in the movie Liar Liar. Dir. Tom Shadyac. Universal Pictures, 1997.

Free will. And with these two words I just opened a can of worms, didn’t I? Modern neuroscience poked its fingers at the eternal problem of whether humans have free will or not, usually with the help of the fMRI, and, more recently trying (and succeeding) to manipulate it with rTMS. But before these fancy techniques, there was the old-fashioned EEG.

In 1983, Libet et al. had 5 subjects sitting comfortably in a chair and watching a clock. Subjects were instructed to make a move of their right hand whenever they want AND to remember the position of the clock hand when they felt the urge to move. During the experiments, the subjects had electrodes on the scalp that measured their cortical activity and electrodes on their hand that measured muscle activity.

The brain activity began at least 1 second before the hand movement and Libet et al. called this activity the “readiness potential”. The muscle activity began 200 miliseconds before the person reported that s/he wanted to move their hand. In other words, brain tells the hand to move and very shortly after you are aware of the want to move your hand. “Brain activity therefore causes conscious intention rather than the other way around: there is no ‘ghost in the machine’.” (Haggard, 2008).

Reference: Libet B, Gleason CA, Wright EW, Pearl DK. (September 1983). Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain, 106 (Pt 3):623-42. DOI: Article

By Neuronicus, 10 October 2015

3 thoughts on “The FIRSTS: brain active before conscious intent (1983)

    1. This is the abstract in the link you provided: “I try to demonstrate a possible contribution of philosophy to the sciences by exposing conceptual confusions in Libet’s empirical work on free will. The elimination of these confusions shows that his research failed to establish what he claimed it does. Libet measured patterns of electric potential in subjects’ brain while asking them to report when they became conscious of an urge or decision to perform a certain action. Relying on the results he concluded that the urge or decision does not affect the action, and hence that we have no free will. However, his research relies on a false picture of what free action involves. Libet thought that a free action should be caused by a mental event – an urge or decision – his model being something like the way one wheel in a mechanism moves another. However, this mechanical picture of the mental is not entailed by our criteria for classifying an action as voluntary, free or intentional. An action is voluntary if the agent would have done something else in the same circumstances had he been given a good reason for that, if he knew what he was doing, if he didn’t act under duress, and so on. Accordingly, Libet’s experiment was irrelevant to the question, whether the subjects acted voluntarily.”


      1. With all due respect to the professor, whom I have never met, he put words in Linet’s mouth; i.e. Libet never claimed – nor any scientist, I believe, based only on Libet’s work – that the decision does not affects the action. On the contrary, in Libet’s own words “In those voluntary actions that are not ‘spontaneous’ and quickly performed, that is, in those in which conscious deliberation (of whether to act or of what alternative choice of action to take) precedes the act, the possibilities for conscious initiation and control would not be excluded by the present evidence” (p. 641 from the above citation). All that the study suggests is that the initiation of action takes place before we are aware of the decision to move. So it’s about awareness of decision. Can we still have free will if the decision was taken unconsciously? That’s a different question. Without trying to be sarcastic (or worse, pedantic), please tell your prof. to read the whole paper, not only the abstract. And the rest of them, if he is to give a talk about Libet’s experiments (I featured only the first).


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