Free will: the mind’s best trick

Free will, which is considered by many central to human nature, has been studied as far back as ancient Greece by philosophers and scientists alike. It is most commonly defined as the capacity to choose between different courses of action in an unimpeded way—that is to say the ability to make choices in which the action and resulting outcome have not been determined by past events.

Decision making—the cognitive process resulting in the selection of a course of action amongst several possibilities—has been extensively studied within the field of neuroscience research. As such, it is in a unique position to attempt to answer the question of free will within humans at a scientific level.

Do we have free will, or are all of our decisions the result of complex neurobiological processes inside the brain? Are we guided by our conscious thoughts and emotions, or by these unconscious neurobiological processes? What’s the neuroscience of free will?

Spoiler alert: I don’t have an answer to these very big questions. But I thought it would be interesting to review some of the neuroscience research on the topic of free will. This article is an adaptation of an essay I wrote for school, so it may get a little bit more technical than usual, but I have removed lots of jargon.

How our behaviour is shaped by unconscious brain activity

An important area of investigation when it comes to free will is the Readiness Potential (RP), a build-up of electrical potential in the brain which manifests itself before a physical movement. In the 1980s, neurologist Benjamin Libet performed a landmark experiment to explore the relationship between brain activity, conscious intention, and action.

Libet asked each participant to flick their wrist occasionally at a time of their own choosing. The three elements Libet measured during the experiment were time of conscious intention, RP, and onset of time of movement. Using a special clock with a rotating dot, the participants were asked to note the position of the dot when they felt the conscious intention to move.

Libet also used EMG surface electrodes to measure muscle activity and determine the precise onset of time of wrist flexion, as well as EGG to record RP in the participants’ brains.

So, what results did he get? Libet found that the RP leading up to a subject’s movement—which can be considered unconscious brain activity—began approximately half a second before the participant was aware of their own conscious intention to move.

These results were surprising, because you would expect for the conscious intention to move to happen before the brain preparing for the movement, not the other way around. Libet’s interpretation was that the brain unconsciously plans our behaviour before we become conscious of our choice, which would call into question the very existence of free will and its validity as a construct.

There are many issues with the Libet experiment—the fact that it uses self-reporting, which can be unreliable, but also the fact that it assumes that RP is related to the decision to move, when it could be anything, such as paying attention to the wrist—and the idea that our behaviour is largely shaped by unconscious activity in the brain is controversial. Other researchers have a more nuanced hypothesis.

Can free will exist without access to the mental processes inside our brain?

Some researchers argue that introspection only gives people access to mental contents such as intentions and feelings, but that mental processes such as neural activity remain inaccessible—resulting in a conflation of mental processes and mental contents, which makes research on the topic of free will difficult.

To better understand this, close your eyes. Look inside your mind. Focus on what you’re feeling and thinking. How much of what’s going on inside your brain can you access this way?

Well, you have access to the result of the neuroprocesses inside your brain—your thoughts and emotions—but you don’t know or feel when neurons are firing or when there’s an increase of a specific neurotransmitter. You’d need to get a brain scan to get access to that information. All you know is that you’re feeling excited, upset, focused, or that you made up you mind to carry on a specific action.

Free will and conscious access to mental content and processes

As a result, even though people may perceive their conscious intentions as the main driver of their behaviour, the reality may be that the experience of free will is instead a post-event rationalisation leading to an artificial causal relation between intentions and actions.

In short, free will may be illusory. Dr Daniel Wegner, an American social psychologist and professor of psychology at Harvard University, called it “the mind’s best trick.”

He defined free will as a function of three elements:

  • Priority. The thought must come before the action.
  • Consistency. The thought must be consistent with the action.
  • Exclusivity. The thought cannot be accompanied with other causes.

He conducted a series of experiments in which people experienced an illusion of control, feeling that their will was shaping events which were actually determined by someone else. His view was that decisions are first made by the brain, and there is a delay before we become conscious of them—at which point we attribute our own free will to the action.

Another way to gain insights into free will is to look at brain-related conditions impairing the ability to control one’s actions. For instance, Tourette’s Syndrome is a neurodevelopmental disorder characterised by verbal and motor tics where patients cannot suppress these involuntary movements. The underlying causes of Tourette’s Syndrome are currently unknown, but it is thought to be linked with motor areas of the brain.

In another example of brain-related condition, damage to the part of the brain connecting the cerebral hemispheres—called the corpus callosum—may result in a phenomenon known as the alien hand syndrome, where patients experience their limbs acting seemingly on their own, without conscious control over their actions.

The fact that damage to the brain or chemical imbalances result in a loss of our ability to exercise our free will may suggest that our experience of free will itself is the result of unconscious neurobiological mechanisms which we can’t control.

If neural activity starts before we formulate a conscious decision, it would explain why neurodevelopmental disorders as well as damage to certain areas of the brain can impair our normal ability to consciously control our actions.

As Wegner explains, this hypothesis does not mean that conscious thought does not cause action; rather that the lack of access to underlying mental processes means our experience of free will is based on invalid inferences. As such,  free will may well be considered “the mind’s best trick.”


Anne-Laure Le Cunff

I’m an ex-Googler, entrepreneur, and part-time neuroscience student at King’s College. If you found this article useful, subscribe to my weekly newsletter about mindful productivity.

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