The Libet Experiment & Question of Free Will

In 1980, Benjamin Libet wanted to find out whether our mind prepared for a movement before we were aware of it. He set up an experiment monitoring brain activity, and found that our brain becomes active 500 milliseconds before we become aware of the decision to make a movement. What does that say about free will?

the full story

In the 1980s, the neuroscientist Benjamin Libet conducted a study that shook the very foundations of what we understand about free will.

the libet experiment

Libet wanted to find out whether our mind prepares for a movement before we are consciously aware of it — and so he and his team set up an experiment.

predecision brain activity

Participants in the study were asked to flex their wrists whenever they felt the urge to do so. While doing so, Libet monitored their brain activity [EEG] through electrodes placed on their heads and found activity before the people decided to move their hands. In other words, the brain started the process, way before the person decided to do it.

free will implications

When we plot a graph measuring time and brain activity, known as readiness potential, the movement started at time 0, participants reported being aware of their decision 150 milliseconds earlier, but the brain actually began to act 500ms before the move.

replication attempts

It didn’t take long before psychologists and philosophers from all over the world discussed Libet’s research and wondered: If our brain initiates a decision before we’re consciously aware of it, then how “free” are our decisions, really?  And ever since, teams of scientists have tried to replicate Libet’s findings, with mixed conclusions.

Libet’s interpretation

Libet himself did not interpret his experiment as evidence that our decisions are predetermined. He said: “The tendency to press a button may be building up for 500 milliseconds, but the conscious mind retains the right to veto any action at the last moment.”

What do you think?

What are your thoughts? And if our brain has already started the process of making a decision before we’re consciously aware of it, to what extent are we truly in control? And if we are not, how would this influence our understanding of personal responsibility for our actions?


Dig deeper!

Classroom activity

In the following activity students will learn about Libet’s Experiment and Free Will 

  • Tell the students to close their eyes and imagine an animal. When it is done, they shall write it down on a piece of paper. 
  • Ask them what animal it was and see if there are some similarities among students. 
  • Ask them why they thought about that animal in particular. Why that one and not another? 
  • Show the class Sprouts’ video on Libet’s Experiment.
  • Ask them now if they think their choice of animal was conscious and the product of free will, or if they think their brains and how they function somehow influenced their choice before they even knew it. 
  • Ask them now what they think of free will.


  • Script: Ludovico Saint Amour di Chanaz and Jonas Koblin
  • Artist: Pascal Gaggelli
  • Voice: Matt Abbott
  • Coloring: Sasalux
  • Editing: Peera Lertsukittipongsa
  • Production: Selina Bador
  • Sound Design: Miguel Ojeda

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