The Misinterpretation of Libet and Our Man in Alaska

One of the primary combat vehicles in the attack on consciousness is based on a set of studies by Benjamin Libet. In this study, people were asked to randomly decide when to a press a button. They were also asked to report exactly when they made the decision to press the button by observing a fast-moving second hand on a nearby clockface. At the same time, their neural activity was recorded using an electroencephalograph. What the original Libet (1983) study showed is that prior to becoming consciously aware of the instantaneous decision to randomly press a button, unconscious activation in the brain was already signaling the upcoming decision up to 500ms before consciousness becomes aware of it. This unconscious activation, called the readiness potential, has been interpreted to suggest that consciousness is epiphenomenal, the last to the party, and certainly not available for free will---if there is such a thing. Consciousness is an illusion is the mantra we often hear.

These interpretations are deeply wrong for several reasons. Far from being an illusion, consciousness does drive actions and the Libet studies make this undeniable.

The first reason is that the Libet study doesn't make any sense unless we allow consciousness to influence behavior. The interpretation most often made is that consciousness does nothing but observe unconscious decision making; consciousness is a one way street with information only entering consciousness but never leaving it. However, this interpretation is impossible if we expect people to report when they became aware of the decision to press the button. If consciousness cannot influence behavior then people cannot report on when things become conscious. If you can tell me what you're consciously thinking about, then your consciousness can drive your actions too.

To make this clear, imagine there is a man in a room in Alaska who learns entirely about the world through mail he receives through a mail slot. He experiences the world only when the rest of the world decides to send him a letter, telling him what is going on outside, in the real world. He only receives mail; he never sends it.

Our man in Alaska is how the Libet study is usually interpreted. But there is a huge plot hole in this interpretation. Suppose you want to know when the man reads a letter and becomes aware of something outside his room? There is only one way to do this: get the man to send a message from inside the room telling us at what time he read the letter.

People in the Libet study reported when they became aware of the decision to press the button. They did so by observing the clock that was also synchronized with their brain recordings. They were able to send a letter from inside the room because they told us where the clock hand was when they become aware of the decision. Therefore, their consciousness was not a one-way street. If it were, they could not have reported on what consciousness contains. Our man in Alaska can send as well as receive mail.

The second reason why Libet has led us to discover that consciousness can control action is because we now know, from recent studies, that consciousness can veto the readiness potential's decision to press the button.

Using a brain-computer interface to signal veto actions at exactly the moment the readiness potential was detected, recent work by Schultz-Kraft (2016) found that people could inhibit the subsequent actions up to 200ms before the button is pressed. The readiness potential begins some 800ms before the person makes the decision, leaving time for consciousness to do its magic. By informing the person in the study about whether or not they should veto the decision to press the button, the Schultz-Kraft study showed that consciousness could veto the decision.

Our man in Alaska is sent a letter about an imminent decision that will be made, but at the same time he is also sent a letter that he should stop this decision. The only way he can do this is to send a letter from inside the room telling the outer world (the unconscious) to veto the decision before the decision is actually made. And it does. So our man gets letters warning him about future actions and he can veto them if he chooses.

Consciousness is alive and well in the Libet-style studies. They provide two clear pieces of evidence that consciousness can influence action. We couldn't report on consciousness if consciousness couldn't influence action. And consciousness can veto unconscious processing when it has the motivation and time to do so.

This allows us to use consciousness to deliberate over possible futures and then use that information to guide action. If you want to know more about the ability to simulate the future and yourself, and how that ability evolved, Stephen Butterfill and I (2015) wrote an article about it a few years ago.