
The Libet experiment (1982): the time at which an EEG signal indicating brain activation for movement occurs is set as zero time, the reported time of awareness of intention to push the button is about 350 milliseconds (0.35 seconds) later, and the actual EKG, the voltage in the finger muscle doing the push, happens about 200 milliseconds later than that.

The Libet experiment (1982): the time at which an EEG signal indicating brain activation for movement occurs is set as zero time, the reported time of awareness of intention to push the button is about 350 milliseconds (0.35 seconds) later, and the actual EKG, the voltage in the finger muscle doing the push, happens about 200 milliseconds later than that.

In experiments, the Libet experiment was a 1982 study conducted by American neuroscientist Benjamin Libet in which the time of onset of “electrical activity” in the cerebrum, the instance of the so-called or readiness potential, of six college students, was measured against the “reported time” of the appearance of the subjective experience of “wanting” or intending to act, with regard to the specific action of choosing to press a button at a specific instance in time. A three step summary of Libet's 1983 study are shown below, which finds a three step time demarcated (delayed) mechanism involved in the so-called conscious action of "choice" to perform an "action", both of which being preceded by an unconscious readiness potential change in the matter of the brain; the time of the readiness potential, in turn, preceded by electromagnetic sensory perception input (not part of the experiment):

The experiment was conducted by a group led by Libet at the physiology department of the University of California, San Francisco, and published in a 1983 issue of Brain as “Time of Conscious Intention to Act in Relation to Onset of Cerebral Activity (readiness-potential): the Unconscious initiation of freely voluntary act”. Libet concluded, from his experimental findings, that: [1]

“Cerebral initiation of a spontaneous, freely voluntary act can begin unconsciously, that is, before there is any (at least recallable) subjective awareness that a ‘decision’ to act has already been initiated cerebrally.”

The Libet experiment soon thereafter became a classic citation of scientific proof that that free will does not exist.

Veto action
Although Libet originally concluded his findings show that people don't have free will, he later recanted on his views to the affect that he argued that people don't have free will with respect to initiation behavior, but might have free will respect to the veto of an action before it becomes effective. [2] American neuroscience research Sam Harris, objects to this recant: [3]

“I think Libet’s reasoning was clearly flawed, as there is every reason to think that a conscious veto must also arise on the basis of unconscious neural events.”

The general issue here is that: yes (a) readiness potential precedes conscious awareness of the "choice" to act by a measurable amount of time, but (b) the "force" of sensory input, which is predominately the electromagnetic force, precedes readiness potential by another measurable amount of time. This logic was first stated in 1847 by Irish physicist James Maxwell as follows: [4]

“The only thing which can be directly perceived by the senses is force, to which may be reduced to light, heat, electricity, sound and all the other things which can be perceived by the senses.”

In sum, points (a) and (b) show that conscious choice to act is preceded and governed by external electromagnetic forces that impede onto the senses of the body of the human molecule. The subject of "veto action" arises in the relative strengths of competing external forces. This was first stated clearly in German physicist Rudolf Clausius' 1875 mathematical introduction, wherein stated: [5]

“Every force tends to give motion to the body on which it acts; but it may be prevented from doing so by other opposing forces, so that equilibrium results, and the body remains at rest. In this case the force performs no work. But as soon as the body moves under the influence of the force, work is performed.”

This is logic is based in French physicist Gustave Coriolis’ 1829 principle of the transmission of work which mathematically quantifies every movement as a type of work derived by a force.


University College London neuroscience researcher Patrick Haggard discussing Libet’s experiment.

University College London neuroscience researcher Patrick Haggard discussing Libet’s experiment.

The example of "movement" in the Libet experiment being the movement of the subject's finger to press a button, which is one of the very simplest types of "models of work" in the study of human movement. In the case of veto action, one external force overrides a previous external force, such that indecision to act or rather a veto of previous intention to act results.

See also
● Trigger action
● Induced movement

References
1. Libet, Benjamin, Gleason, Curtis A., Wright, Elwood W., Pearl, Dennis K. (1983). “Time of Conscious Intention to Act in Relation to Onset of Cerebral Activity (readiness-potential): the Unconscious initiation of freely voluntary act” (Google books), Brain, 106 (pg. 3): 623-42.
2. (a) Libet, Benjamin. (1999). “Do We Have Free Will?”, Journal of Consciousness Studies, 6(8-9): 47-57.
(b) Libet, Benjamin. (2003). “Can Consciousness Experience Affect Brain Activity?”, Journal of Consciousness Studies, 10(12): 24-28.
3. Harris, Sam. (2010). The Moral Landscape (pgs. 103, 215). Free Press.
4. (a) Maxwell, James. (1847). “Exercise for Hamilton on the properties of matter”, class of philosopher William Hamilton (1788-1856), Edinburg University.
(b) Mahon, Basil. (2003). The Man who Changed Everything: the Life and Times of James Maxwell (pg. 25). Wiley.
5. Clausius, Rudolf. (1875). The Mechanical Theory of Heat (section: Mathematical Introduction: on Mechanical Work, on Energy, and on the Treatment of Non-Integrable Differential Equations, pgs. 1-20). London: Macmillan & Co.