So far in this series we have heard from scientists on both sides of the debate over free will. Now, we'll go after a different question: Does free will matter?

Experimental psychologists have been studying what happens when our beliefs about free will are altered. Their results suggest that our opinions about free will may be even more important than free will itself, for if we come to believe that free will is truly an illusion, society might become a less friendly place.

In 2008, Kathleen Vohs, a psychologist and marketing professor at the University of Minnesota, ran an experiment to probe how subjects' beliefs about free will influence their behavior. In each trial, one group of subjects read statements asserting that that our actions are completely predetermined by environmental and genetic factors--that there is no free will. A second group read neutral statements. Then, the participants were given a test of character. In one case, they were asked to complete a computerized math test that was "flawed"--it sometimes "accidentally" showed the correct answer. Subjects were instructed to quickly click away the answer and ignore it, but they had the opportunity to cheat of course.

In a similar experiment, subjects completed another test and were instructed to take a certain amount of money from an unattended source for each correct answer that they scored. Though subjects believed no one was watching--and thus they could take as much money as they wanted--Vohs and her colleagues were actually monitoring the pot.

This is the third part in a four part blog series on the science of free will.

So far in this series, we've focused on scientists who are trying to disprove the existence of free will. But Jeff Miller of the University of Otago in New Zealand thinks these investigators have got it backwards. "We know it's almost impossible to prove that something does not exist (e.g. Loch Ness Monster)," says Miller. "Even after we have looked and looked, it is still possible that it's out there."

So are there any researchers who believe their work provides support for free will? Yes. Björn Brembs, a neurobiologist at the Free University of Berlin, has found evidence of free will in an unlikely place: the mind of a fly. Even when put under strictly controlled stimuli, flies will act in unpredictable ways. Unlike a machine, which will always give one predictable output for one input, even a simple fly brain will react differently to the same input in multiple trials.

Drosophila melanogaster, free thinker. By Mr.checker (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

This kind of variability might be even be an evolutionary adaptation to help animals escape predators. The more unpredictably an animal maneuvers when it is being chased, the more easily it can escape danger. Another use is in exploration. If animals never wandered around without a goal, they would not find new habitats and food sources. Variability is also important in learning. Brembs gives the example of a toddler learning to speak: At first the child is very variable in her language, saying "momoo, mumoo, momma" until she reaches the right word, "mommy."

This is part two of a four-part blog series on the science of free will.

In the previous entry in this series, I described a classic free will experiment performed by Benjamin Libet in the 1980s. Brain scanning technology has come a long way since then. Can modern scanning shed more light on free will?

In 2007, the neuroscientist John Dylan Haynes of the Bernstein Center for Computational Neuroscience in Berlin, Germany, ran a new experiment. In each trial a subject was given a window of time to make a decision and act on it. The decision was to either press a button in the left hand or a button in the right hand. At the same time, the subject was watching a screen which flashed a series of letters in rapid succession. Subjects were asked to note which letter was being displayed on the screen at the moment that they made the decision to press one button or another.

While Libet used EEG technology, Haynes used more advanced fMRI. Both technologies record brain function in action, but an fMRI reading provides more spatial resolution--it more precisely identifies the specific parts of the brain as they activate. Haynes claimed that, by analyzing the the fMRI data from one specific part of the brain, frontopolar cortex, he could predict which button the subject would choose--left or right--with 60% accuracy seven whole seconds before the participant was consciously aware of his or her decision.

Few scientists are convinced that this is the death knell for free will, though. Marcel Brass, of the University of Ghent, Belgium, points out that the 60% figure is not that much better than chance, but adds, "It shows our decisions are influenced by stuff that happens in our brain before we decide. But it is not showing our decisions are completely pre-determined." Jeff Miller, of the University of Otago in New Zealand, agrees: "Finding that brain activity predicts a decision does not undermine free will." He explained the brain activity used to make the prediction could just be a leaning towards one choice or another, and that the final decision could still have been made consciously.

Haynes himself accepts this possibility. "Maybe this early signal isn't a full decision, it's just like a nudge that you get, it's just biasing you one way, but its not really finally making up your mind." So what is "making up your mind?"

Not free will, says Haynes. "Decisions are caused by unconscious brain processes, then consciousness kicks in later." In Haynes' view, our conscious decisions are predetermined by brain activity even if we cannot yet completely decode that activity. "It is subjective experience that you think that you have free will. It's something that is implausible, its incompatible with the scientific deterministic universe anyway."

So why weren't Haynes' predictions perfect? Haynes lays the blame on technology. FMRI probes regions of the brain but cannot access the activity of single neurons. The next step, Haynes anticipates, may be the experiments currently going on that do monitor single neurons.

At this point, you might wonder whether John Dylan Haynes went into this research with an anti-free will agenda in mind. He would tell you that the answer is no: "People talk to me about determinism and free will a lot, but I actually thought the experiment was about conscious and unconscious processing." And why does he focus on this area? Simply, "I am interested in interesting questions."

To Mark Hallett, chief neurologist at the Human Motor Control Section of the National Institute of Neurological Disorders and Stroke at the National Institutes for Health, the question is of more than philosophical interest. He believes that it could help patients who suffer from a relatively common condition called a psychogenic movement disorder. "The movements look like they are voluntary, but the patients say they are involuntary. It's hard to understand that unless we can understand where the notion of the voluntariness comes from," says Hallett. From studying these patients and performing his own experiments, which explore the human perception of volition, he has concluded, "Free will is not a driving force for movement."

Today we are learning more about how the brain prepares our body to perform actions. At the very least we know as Marcel Brass said, some "stuff" happens in our heads before we are aware of it happening. Some take this as evidence against free will as the cause of our actions, and some do not feel O.K to go that far yet. As technology improves we can predict with more accuracy what that "stuff" might be telling us, but as Haynes noted there is a difference between finding brain patterns that are predictive of our actions and ones that determine our actions. It will be a long time before we have a definite answer as to how exactly real-life decisions, which have greater importance than deciding to press a button, work.

Do humans have free will? Philosophers have discussed and debated free will for thousands of years. The question used to be, "Do we get to decide our actions or does God dictate them?" Later it became, "Is our soul a separate entity from our body that tells our body what to do?" Today, science isn't in the business of testing for God or the soul, and we believe that the mind is a product and part of body. Thoughts are patterns of neurons firing in your brain.

Now, scientists are beginning to probe the connection between thought and action. In a series of blog posts over the coming week, I'll discover how far that research has come--and how far it has yet to go.

Part 1: Free Will in the Lab

Part 2: Is Free Will an Illusion?

Part 3: In Defense of Free Will

Part 4: Does Free Will Matter?

As individuals, we believe that our thoughts bring about our actions. First we ask a question to ourselves: "What shall I do now?" Next we make the decision: "I will bake a cake now." Finally, we perform the action; we bake the cake. We believe we baked the cake because of that inner dialogue. But what if the brain "decided" to bake the cake long before the inner dialogue gave voice and awareness to the decision? The brain may have been sending signals to the body to go get the flour before we even thought, "I will bake a cake"! If this is true, you were going to bake that cake all along, and your thoughts arose in order to explain your actions to yourself--the thoughts are, to torture a metaphor, just the icing on a cake that your brain baked before you ever knew it.

With modern science we have the ability to watch brains as they function, something the ancient philosophers could barely have imagined. Does this mean we can now finally figure out how free will works? Can scientists witness our decisions in action? Or will it turn out that free will is just an illusion? The results of experiments in the field and what they mean for free will is hotly debated. In this series, I hope to untangle the science from the semantics and the data from the dogma--without getting stuck in the mire of metaphysics.

This is the first part in a four part series on the science of free will.

First, some history. Though philosophers have debated free will for over 2000 years, scientists only began to take it on experimentally in the 1980s, when Benjamin Libet (1916-2007), a physiologist at the University of California San Francisco, performed a now-classic experiment. Libet instructed participants to flex their wrists whenever they felt the urge to do so, within a window of a few seconds. Subjects watched a rapidly moving clock and were instructed to note to themselves, and later report to the researchers, the time on the clock when they had come to a decision to move. At the same time, their brain activity was monitored by EEG. Libet was looking for a distinct change in brain activity that he called the "readiness potential," which he believed was an indicator of the brain preparing for movement.

Libet found that the readiness potential appeared, on average, 350 milliseconds before subjects reported that they had made a decision. This meant that the order of the events was: 1) A subject's brain prepared to move the wrist, 2) The subject said to himself, "I have decided to move my wrist," 3) The subject's wrist moved. To Libet, this suggested that the subject's decision was not truly the cause of the movement, since the brain was preparing the movement a fraction of a second before the subject made a conscious decision. Libet came to the conclusion that our conscious control over our actions is limited--or may not exist at all. Wow, sounds like free will just took a pretty hard blow. But did it really?

Jeff Miller of the University of Otago, New Zealand, was set on finding out whether the readiness potential signal was in fact a definite indicator of movement preparation. So, he recreated Libet's experiment, with a twist: This time, subjects did not move on every trial. His team found no evidence of stronger signal before a decision to move than before a decision not to move. They observed the readiness potential both before movements and when no movement happened, meaning it was not a consistent indicator of movement preparation. Since the readiness potential does not cause movement, something else could be the true cause of the movement, "maybe even the person's free will," said Miller.

What exactly does the readiness potential indicate, then? As Miller explained via email, he believes "it reflects some kind of general engagement with this task. I realize that's a very vague answer, but we need to pin down precisely what experimental conditions are necessary to produce this pattern of EEG activity before we can really say what it reflects."

Libet did leave some space in his conclusion for free will to exist, but in a more limited role. He thought there might be conditions in which the conscious mind takes over and "vetoes" spontaneous behavior. He noted that, "subjects have reported some recallable conscious urges were 'aborted.'" In these instances the subject's subconscious presented the urge, or option of how to act, and his conscious mind chose whether or not to act on it.

Critics like neuroscientist John Dylan Haynes, however, argue that the "veto" isn't necessarily a product of free will, either. "Every conscious process, even a veto, will have its brain correlate, its unconscious precursor," says Dylan Haynes. To Dylan Haynes, the very idea of a veto--or, as Mele refers to it, "free-won't"--is an artifact of the discredited philosophy known as "dualism," the notion that mind or consciousness and body or brain/subconscious activity are two separate entities.

Libet's critics also take issue with the design of his experiment, specifically with how subjective the self-reported timing method was. Marcel Brass of the University of Ghent, Belgium has worked on an experiment that proves that a subject's perception of the time of their intention can be manipulated by playing a tone at different intervals after they perform an action. Mark Hallett at the National Institute of Health worked on an experiment that aimed to provide a more objective measure of the time of intention using the subject's real-time decision of whether or not there was a thought to move when a tone occurred.

What did we get out of Libet's studies then? "The work was an excellent stimulus for useful discussions about the challenge of relating neuroscience to philosophical questions about consciousness and free will," says Miller. "Of course these are tough questions and they will not be settled any time soon."

To learn about the more recent work inspired by Libet's experiment, come back to read the next installments in this series.

In his theory of special relativity, Einstein showed that the very idea of simultaneity--of two events occurring at the same time in different places--is flawed. Simultaneity is all relative, Einstein argued; it depends on your perspective or, technically, your reference frame. Yet we at NOVA note the passing of Norman Ramsey, the physicist whose work led to the most accurate timekeeping devices in history, with special poignancy due to a personal sense of simultaneity; we are just about to begin our exploration of time in tonight's episode of The Fabric of the Cosmos.

Norman Ramsey shared the 1989 Nobel Prize in physics for his contributions to the invention of the hydrogen maser and the cesium atomic clock. Ramsey began working on atomic spectroscopy, a way of discovering the structure of atoms by analyzing the wavelengths of light that they release and absorb, at Columbia University in the late 1940's. He then moved to Harvard and in 1949 invented a new way to measure the frequency of photons released by atoms and molecules with even greater accuracy. In 1960, Ramsey contributed to the invention of the hydrogen maser, which was also put to use as a timekeeping device. Ramsey literally helped redefine time, not as something to be measured by the motion of Earth and Sun, but to be "ticked off" by the vibrations of an atom.

Today's best atomic clocks are so accurate that they won't gain or lose a second for the next 138 million years. Atomic clocks are critical to GPS and modern communications; they help radio astronomers see the universe with pinpoint precision; and ironically, they have even been used to confirm Einstein's ideas about the plasticity of time. Ramsey did not at first realize that his work would have these far-reaching applications. In fact, as recounted by The New York Times, he once said, "I didn't even know there was a problem about clocks initially. My wristwatch was pretty good."

For more about Ramsey's work, we recommend coverage from: