Do we have free will in action

The Libet experiment

Free will in experiment

So far, brain research has found little evidence that there is free will. Some experiments even show the opposite. The "Libet experiment" became particularly famous.

The American neurophysiologist Benjamin Libet carried out the experiment in the 1980s. He wanted to measure how much time elapsed between a conscious decision to act and the corresponding body reaction.

In order to determine the point in time of the decision to act, Libet used a kind of clock: A point of light moved on a circular scale, and the test person was asked to note the position of the point of light on the scale at the time of his decision. With this arrangement, Libet was able to determine the point in time when the subject was consciously perceived to an accuracy of around 50 milliseconds.

At the same time, the researcher measured the subject's brain waves and muscle movements so that he could not only determine the exact point in time of a body movement, but also what is known as the readiness potential. This increases as the brain prepares for movement in the motor cortex (an area of ​​the outer layer of the cerebrum).

The experiment stipulated that the test subjects should simply raise their hand: either spontaneously or according to a certain, self-selected schedule. A simple, free decision. The result of the experiment amazed the scientist.

Under all conditions, it was found that the brain was already preparing the movement of the hand at a point in time at which the test subject had not even had the intention of actually executing the movement. Up to one second before the actual decision was made, the activity of the motor cortex signaled the intention to act later.

Free or not free?

The sequence of an action that was thought to be free was thus turned upside down: It seemed that the decision to raise one's hand was made by other areas of the brain, regardless of the subject's consciousness.

The Libet experiment caused a sensation because it seemed experimentally proven that it is not conscious volition but subconscious processes that are responsible for our actions. The results suggested that the will is a brain-generated sensation rather than an independent entity.

However, numerous critics of the experiment raised objections to such an interpretation: On the one hand, the exact timing of a conscious decision to act cannot be precisely determined by the experimental set-up. On the other hand, raising a hand under the test conditions is not a real decision of the will.

But even if Libet's experiment could not provide unequivocal proof against the possibility of free will decisions, brain research is much further removed from proof of free decision-making ability. The results of the research suggest that the will is a brain-generated sensation rather than an independent entity.

Do we have free will or not? Does the brain dictate our supposedly own decisions? Even today, neuroscientists cannot conclusively answer this question. However, recent studies have been able to partially refute the results of the Libet experiment.

In 2015, a study by the "Bernstein Center for Computer-Aided Neurosciences" at the Charité in Berlin showed that test subjects can still veto - even after the willingness potential has begun, which according to neurophysiologist Libet already expires before we consciously decide on an action.

According to the Berlin researchers, we can consciously cancel a movement up to a certain point in time (the so-called "point of no return"). And: Even after this point, we can still change the action.

The results of a Swiss study from 2020 also call the Libet experiment into question. The scientists were able to show that the readiness potential is related to breathing. This is an indication that the brain does not anticipate our decisions, but rather turns out the readiness potential through natural body processes - such as the breathing rhythm.

These studies suggest that our will is at least freer than long assumed.