Do we have free will? What neuroscience can tell us about our decision-making abilities

Do we have free will? That question was once the preserve of philosophers and theologians, but is now a subject of inquiry for neuroscientists. With the aid of advanced functional magnetic resonance imaging, or fMRI – scans that can measure brain activity in detail – neuroscientists are confident that they can answer the question. What exactly is free will? Whenever we make any kind of decision – whether it’s a trivial one, like what jacket to wear, or a more important one, like what university to attend – we assume that our mind weighs the options, decides a course of action and instructs our brain to carry it out. Neuroscientists, however, say the physical brain is not the workhorse of the mind, but in fact the controlling force behind every decision we make. According to Dr Hannah Critchlow, a neuroscientist at Cambridge University in Britain and author of the book The Science of Fate, all our decisions are made by the brain without us consciously knowing why. The brain makes the decisions based on information of which we are not consciously aware, Critchlow says, by referring to a range of deeply submerged criteria. These include hereditary genetic preferences, past experiences and environmental factors that our senses have informed our brain about. The part of us that is conscious of the final decision is just the result of a complex series of calculations. We have trillions of connections in our brain, and these give us each a unique view of reality, and is why we can make different decisions to others Dr Hannah Critchlow “If you are standing at a crossroads trying to decide whether to go left or right, there are going to be certain cues that will lead you to have a bias towards turning either left or right,” Critchlow says. “Such cues are behind simple decisions, and more complex decisions like choosing the friends you want to surround yourself with. They are also behind higher level conceptual behaviour, such as the things you believe in.” Our genes play a big part in providing these cues, Critchlow says. We are not born with a blank slate – our genes are hard at work while we are in the womb, constructing the neural connections that will form the basis for our mental and physical attributes later in life. She refers to a consortium of scientists from across Europe, based at King’s College Hospital in London, who have developed a new fMRI scanning method to examine how genes determine a fetus brain’s neural circuitry while in the womb. Critchlow says that the scientists discovered that the way the inherited genes are expressed in the embryo dictates how the 86 billion nerve cells that make up our brains start connecting with each other. “The process is driven by the genes you have inherited from your mum and dad, which make a kind of instruction manual for putting together your brain – it’s a bit like an instruction manual for Ikea furniture,” Critchlow says. These cells form a “circuit board” of 100 trillion connections, and this circuit board determines how our brains will develop. The King’s College Hospital team is focusing on medical conditions, and what they are finding is there are biomarkers within the foundations of the brain that seem to align with whether a baby is likely to emerge with depression, for instance. These biomarkers are related to symptoms that may not emerge until decades later in that baby’s life.” Although this neural circuitry is established when we are young, there is certainly room for change as we grow, because our experiences also affect the decisions we make. “The neural connections change throughout life. We develop a unique view of the world that results from our own experiences, along with our genetic make-up. Scientists are finding out more and more about how our experiences can affect the circuitry in the brain,” she says. “The brain is sculpted to form a particular circuit, by referring to our genetics and our experiences. That affects how we see the world, what our sense of reality is like, and what kind of decisions we make. We have trillions of connections in our brain, and these give us each a unique view of reality, and is why we can make different decisions to others.” In our teens, our neurons forge many new connections based on our experiences. But after adolescence, a lot of these connections are pruned. The brain decides which connections are useful and cuts the rest. To a certain extent, our personalities and behaviour become fixed after adolescence. Once our brains have established a world view, it can be difficult to change, Critchlow says. Brains prefer to stick with what they know rather than do something new. “The brain is very busy buzzing around processing information as it comes in. So it uses the assumptions that are embedded within it to make short cuts while it is processing that information. If it didn’t do that, it would become almost paralysed by all the information that’s coming in,” she says. As we age, our brains are more likely to fit information into a pre-existing pattern rather than take on new beliefs. This is a matter of energy efficiency, Critchlow says. “Any conflicting information taken from the outside world [is ignored]. It will cost quite a lot of energy for the brain to shift its connections to change our beliefs. So the brain just takes bits of information that it agrees with, and we go deeper down the path of that narrow trajectory.” Where does all this leave the mind? Impossible as it may seem, the mind actually may not exist at all. At best, the mind is a kind of higher-level filter constructed by the brain to make sure we operate efficiently, and at worst it is an illusion – a by-product of the chemical processes that are taking place in the brain. Critchlow says that such discoveries do not mean that we are all machines, and neuroscience is not something to be feared. “It’s quite human to try and understand a little bit about how we lead our lives, how our life stories emerge and what sets us apart as individuals,” she says. “Neuroscience is helping us to understand this a little bit better.”