Are We Puppets of Our Brain?

A neurologist explains the Libet Debate, the experiement that questioned free will.

Posted November 23, 2025 | Reviewed by Gary Drevitch

The name of my lab during my fellowship at NIH 20 years ago was the Human Motor Control Section, and it used various electrical tools to study the physiology behind human movements. I was never a gadget person, so the tangle of monitors, colored cords, amplifiers, and alligator clips felt, at times overwhelming. But one test was simple enough: eliciting the Bereitschaftspotential or the “Readiness Potential (RP)” through electroencephalogram (EEG).

The standard view of voluntary action is intuitive: A person forms a conscious intention to move, then the brain issues the command to execute it.

That naturally led to a simple question: Is there a brain signal preceding the movement in the motor cortex (and other brain areas responsible for movement)? Wouldn’t that signal represent the brain’s intention and command to move?

We connected ourselves to EEG electrodes and voluntarily contracted the same muscle; for example, by pinching our fingers. EEG usually detects dramatic cortical events like seizures, so an individual finger pinch didn’t visibly alter the trace. But if we added recordings from multiple attempts, say 100 times, a slow, negative signal appeared over the motor cortex and supplementary motor area, beginning one to two seconds before the movement. While it is difficult to know what this signal truly represented, activity was happening in the motor area of the brain before the movement, and this signal was named the RP.

In 1983, Benjamin Libet did a series of experiments to further understand the relationship between our intention to move and RP. He had subjects flick their finger spontaneously without any cue, while watching a special clock that circled every 2.6 seconds. They were then asked to report the moment they first became aware of their intention to move. Libet called this time W time , for “willing.”

As expected, the RP appeared before the movement. But more provocatively, the RP began before the W, the reported moment of conscious intention, by several hundred milliseconds. Libet interpreted this to mean that the brain initiates voluntary actions before we consciously decide, and so an obscure scientific experiment sparked a large and heated debate involving philosophers and popular media about the existence of free will . Libet’s experiment was cited as evidence that free will might be an illusion.

Examining the Claims More Carefully

Libet’s argument rests entirely on temporality : RP precedes W. Although the basic temporal relationship has been replicated, both measurements (RP and W) are more complicated than they appear. Let’s think of counterarguments together.

Is W really the moment of intention? The moment we become aware of an intention is not necessarily the same as the moment we form that intention. And reporting W requires subjective interpretation, memory , and attention , processes far removed from the instantaneous neural events they supposedly reflect. So it is unclear what W truly represents.
Are the decisions in Libet-style tasks representative of real decisions? Libet’s tasks rely on arbitrary choices—flick your finger spontaneously—rather than deliberate choices made for reasons. Later research showed that arbitrary and deliberate decisions may rely on different neural mechanisms. The RP appears reliably for arbitrary actions but not for more deliberate decisions, such as clicking the mouse to choose which charity to donate to.
What does the RP actually represent? The presence of an RP before movement does not prove it causes the movement. Because the RP is extracted by back-averaging many trials only after a movement occurred, it suffers from selection bias : We see the build-up only in the trials that led to an action. We cannot back-average neural activity when no movement occurred.

In fact, newer evidence suggests the RP may not be a distinct, purposeful signal at all. Instead, it may reflect random fluctuations in neural activity that occasionally accumulate enough to trigger a movement.

Schurger et al. formalized this with a stochastic accumulator model: Spontaneous movements occur when background noise in motor areas crosses a threshold. The RP is simply the statistical “average” shape of these fluctuations. Further studies have shown that even after early motor-preparatory activity begins, subjects can consciously veto an intended movement.

As a kid, I used to play this mental game. I would pretend to choose option A—say, pasta from a menu—and then at the last second, I’d change my order to B, a sandwich, as a proof of my free will. Is this a proof of free will? Probably not. But it’s fascinating that researchers are trying to study these questions in scientific settings.

So the current theory is this: Movement emerges from probabilistic accumulation of neuronal activity, rather than a single deterministic “decision signal.” Conscious intention interacts dynamically with these processes, modulating and shaping action.

A Broader Reflection on Free Will

Another misconception is that, in order to say we have free will, we must be acutely conscious of every intention. Yet many everyday actions—opening doors, brushing teeth, driving, even mindlessly eating chips—occur semi-automatically. We are conscious in general but are unclear whether we consciously articulate, in our minds, every micro-decision. Still, if asked, retrospectively, we would report that these actions occurred as a result of our decision and free will.

In other words, what we think of as consciously intending (the kind of intention that underwrites free will and action) is different from being conscious of having an articulated intention right before the action. Furthermore, simply being conscious of an intention is not the same as having an intention that expresses our agency and values. Neuroscience can measure the former only imperfectly and barely approaches the latter.

What also fascinates me is how often intention and action diverge: the missed free throws, missed 20-yard field goal, double faults. In everyday life, we clumsily drop food, spill water, and misspeak. At other times, movements occur without any conscious intention at all. This variability makes the idea of stochastic neural fluctuations intuitively appealing.

In the end, Libet’s experiments don’t settle the free will debate, but they have deepened it. They show that the machinery behind our actions is more dynamic, more probabilistic, and more surprising than we once imagined. But they also reveal that conscious intention is not a single moment on a clock; it is a broader, richer capacity shaped by experience, values, memory, and reflection. Rather than proving we are puppets of unconscious impulses, the science reminds us that human agency lives in the ongoing interaction between automatic processes and the choices we make over time. And that space—messy, noisy, and beautifully human—is where free will still resides.

Libet B, Gleason CA, Wright EW, Pearl DK. Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain. 1983 Sep;106 (Pt 3):623-42. doi: 10.1093/brain/106.3.623. PMID: 6640273.

Triggiani AI, Kreiman G, Lewis C, Maoz U, Mele A, Mudrik L, Roskies AL, Schurger A, Hallett M. What is the intention to move and when does it occur? Neurosci Biobehav Rev. 2023 Aug;151:105199. doi: 10.1016/j.neubiorev.2023.105199. Epub 2023 Apr 27. Erratum in: Neurosci Biobehav Rev. 2023 Sep;152:105318. doi: 10.1016/j.neubiorev.2023.105318. PMID: 37119992; PMCID: PMC10330627.CopyDownload .nbib

Schurger A, Sitt JD, Dehaene S. An accumulator model for spontaneous neural activity prior to self-initiated movement. Proc Natl Acad Sci U S A. 2012 Oct 16;109(42):E2904-13. doi: 10.1073/pnas.1210467109. Epub 2012 Aug 6. PMID: 22869750; PMCID: PMC3479453.

Maoz U, Yaffe G, Koch C, Mudrik L. Neural precursors of decisions that matter-an ERP study of deliberate and arbitrary choice. Elife. 2019 Oct 23;8:e39787. doi: 10.7554/eLife.39787. PMID: 31642807; PMCID: PMC6809608.

Schultze-Kraft M., Birman D., Rusconi M., et al. The point of no return in vetoing self-initiated movements. Proc Natl Acad Sci USA. 2016;113(4):1080-1085. DOI 10.1073/pnas.1513569112.

Travers E, Friedemann M, Haggard P. The Readiness Potential reflects planning-based expectation, not uncertainty, in the timing of action. Cogn Neurosci. 2021 Jan;12(1):14-27. doi: 10.1080/17588928.2020.1824176. Epub 2020 Nov 6. PMID: 33153362.

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Michiko Kimura Bruno, M.D., is a Movement Disorder Neurologist, practicing in Honolulu.

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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.