THE PEOPLE WHO KNOW WHAT YOU’RE GOING TO DO BEFORE YOU DO
Not only do your neurons know what you’re going to do before you do, but neuroscientists now think they might even be able to alter your decisions before you are aware of having made them. Adding fuel to the age-old debate about whether we truly have free will, Gabriel Kreiman of Harvard Medical School told attendees at the festival that he is finding out more about how our will, or ‘volition’, is controlled within the brain. Kreiman and his colleagues have previously shown that monitoring the brain activity of people asked to perform a simple physical task enables the scientists to predict when participants are going to move before they become aware of deciding to act. In these studies, they had access to epilepsy patients who had electrodes implanted to help
locate where their seizures started from. Using these sensors, Kreiman and colleagues were able to record the activity of over 1,000 brain cells in two areas known as the frontal and temporal lobes (at the front and side of the head). Putting the patients in front of a computer, they asked them to click the mouse and remember the reading on a clock whenever they decided to. Before moving their hand – and just before the patients were aware of deciding to click – groups of brain cells gradually increased their activity. These ‘getting ready’ signals were seen in brain regions believed to be responsible for preparing movements (the supplementary motor area), and one of the brain’s reward and attention areas (the anterior cingulate cortex). In another experiment they were able to predict which hand people chose to use. These rather mysterious results tally with a
similar experiment that used brain imaging and found decisions could be predicted as much as ten seconds before conscious awareness. The scientist behind that work also presented findings at the festival, which showed that we can now predict abstract decisions, such as whether to add or
subtract. Kreiman believes these results may mean that neurons’ activity builds up until a threshold is reached, when the decision enters awareness and an action is taken. He is now working out ways to watch this in real time to find out whether it is possible to change a decision before it is acted on and also whether there is a ‘point of no return’. He cautioned: “We’re not saying we can make predictions about what you’re going to have for lunch tomorrow or who you’re going to marry in five years – we’re making very specific small claims about a very simple decision.” But he then added: “Our actions and will are totally dictated by ensembles of neurons (brain cells) and the problem of free will can ultimately be understood as the firing of neurons.”
Gabriel Kreiman at the posttalk press conference.