Taking Aim at Free Will - Kreiman Lab

FEATURENEWSTAKING AIM ATFREE WILLScientists think theycan prove thatfree will is an illusion.Philosophers areurging them tothink again.FLATLINER/GETTYBY KERRI SMITHTHE EXPERIMENT HELPED TO CHANGE JOHN-DYLAN HAYNES’S OUTLOOK ON LIFE.In 2007, Haynes, a neuroscientist at the Bernstein Center for Computational Neurosciencein Berlin, put people into a brain scanner in which a display screen flashed a succession ofrandom letters 1 . He told them to press a button with either their right or left index fingerswhenever they felt the urge, and to remember the letter that was showing on the screen whenthey made the decision. The experiment used functional magnetic resonance imaging (fMRI)to reveal brain activity in real time as the volunteers chose to use their right or left hands. Theresults were quite a surprise.1 SEPTEMBER 2011 | VOL 477 | NATURE | 23© 2011 Macmillan Publishers Limited. All rights reserved

FEATURENEWSwill like that, says Mele. Many are materialists— believing that everything has a physicalbasis, and decisions and actions come frombrain activity. So scientists are weighing in ona notion that philo sophers consider irrelevant.Nowadays, says Mele, the majority ofphilosophers are comfortable with the ideathat people can make rational decisions in adeterministic universe. They debate the interplaybetween freedom and determinism — thetheory that everything is predestined, either byfate or by physical laws — but Roskies says thatresults from neuroscience can’t yet settle thatdebate. They may speak to the predictabilityof actions, but not to the issue of determinism.Neuroscientists also sometimes have misconceptionsabout their own field, says MichaelGazzaniga, a neuroscientist at the University ofCalifornia, Santa Barbara. In particular, scientiststend to see preparatory brain activity asproceeding stepwise, one bit at a time, to a finaldecision. He suggests that researchers shouldinstead think of processes working in parallel,in a complex network with inter actions happeningcontinually. The time at which onebecomes aware of a decision is thus not asimportant as some have thought.BATTLE OF WILLSThere are conceptual issues — and then thereis semantics. “What would really help is ifscientists and philosophers could come to anagreement on what free will means,” says Glannon.Even within philosophy, definitions offree will don’t always match up. Some philosophersdefine it as the ability to make rationaldecisions in the absence of coercion. Somedefinitions place it in cosmic context: at themoment of decision, given everything that’shappened in the past, it is possible to reach adifferent decision. Others stick to the idea thata non-physical ‘soul’ is directing decisions.Neuroscience could contribute directly totidying up definitions, or adding an empiricaldimension to them. It might lead to a deeper,better understanding of what freely willingsomething involves, or refine views of whatconscious intention is, says Roskies.Mele is directing the Templeton Foundationproject that is beginning to bring philosophersand neuroscientists together. “I think if we doa new generation of studies with better design,we’ll get better evidence about what goes onin the brain when people make decisions,” hesays. Some informal meetings have alreadybegun. Roskies, who is funded through theprogramme, plans to spend time this year inthe lab of Michael Shadlen, a neuro physiologistat the University of Washington in Seattle whoworks on decision-making in the primatebrain. “We’re going to hammer on each otheruntil we really understand the other person’spoint of view, and convince one or other of usthat we’re wrong,” she says.THAT THERE ARE SOME PHYSICALFACTORS THAT INFLUENCE DECISION-MAKING SHOULDN’T BE A SURPRISE.Haggard has Templeton funding for aproject in which he aims to provide a way toobjectively determine the timing of consciousdecisions and actions, rather than rely onsubjective reports. His team plans to devisean experimental set-up in which people playa competitive game against a computer whiletheir brain activity is decoded.Another project, run by Christof Koch,a bioengineer at the California Institute ofTechnology in Pasadena, will use techniquessimilar to Fried’s to examine the responses ofindividual neurons when people use reason tomake decisions. His team hopes to measurehow much weight people give to different bitsof information when they decide.Philosophers are willing to admit thatneuro science could one day trouble the conceptof free will. Imagine a situation (philosopherslike to do this) in which researcherscould always predict what someone woulddecide from their brain activity, before thesubject became aware of their decision. “If thatturned out to be true, that would be a threat tofree will,” says Mele. Still, even those who haveperhaps prematurely proclaimed the death offree will agree that such results would have tobe replicated on many different levels of decision-making.Pressing a button or playing agame is far removed from making a cup of tea,running for president or committing a crime.The practical effects of demolishing freewill are hard to predict. Biological determinismdoesn’t hold up as a defence in law. Legalscholars aren’t ready to ditch the principle ofpersonal responsibility. “The law has to bebased on the idea that people are responsiblefor their actions, except in exceptional circumstances,”says Nicholas Mackintosh, director ofa project on neuroscience and the law run bythe Royal Society in London.Owen Jones, a law professor at VanderbiltUniversity in Nashville, Tennessee, who directsa similar project funded by the Mac ArthurFoundation in Chicago, Illinois, suggests thatthe research could help to identify an individual’slevel of responsibility. “What we are interestedin is how neuroscience can give us a moregranulated view of how people vary in theirability to control their behaviour,” says Jones.That could affect the severity of a sentence, forexample.The answers could also end up influencingpeople’s behaviour. In 2008, Kathleen Vohs, asocial psychologist at the University of Minnesotain Minneapolis, and her colleagueJonathan Schooler, a psychologist now at theUniversity of California, Santa Barbara, publisheda study 5 on how people behave whenthey are prompted to think that determinismis true. They asked their subjects to read oneof two passages: one suggesting that behaviourboils down to environmental or genetic factorsnot under personal control; the other neutralabout what influences behaviour. The participantsthen did a few maths problems on acomputer. But just before the test started, theywere informed that because of a glitch in thecomputer it occasionally displayed the answerby accident; if this happened, they were to clickit away without looking. Those who had readthe deterministic message were more likely tocheat on the test. “Perhaps, denying free willsimply provides the ultimate excuse to behaveas one likes,” Vohs and Schooler suggested.Haynes’s research and its possible implicationshave certainly had an effect on how hethinks. He remembers being on a plane on hisway to a conference and having an epiphany.“Suddenly I had this big vision about the wholedeterministic universe, myself, my place in itand all these different points where we believewe’re making decisions just reflecting somecausal flow.” But he couldn’t maintain thisimage of a world without free will for long.“As soon as you start interpreting people’sbehaviours in your day-to-day life, it’s virtuallyimpossible to keep hold of,” he says.Fried, too, finds it impossible to keep determinismat the top of his mind. “I don’t thinkabout it every day. I certainly don’t think aboutit when I operate on the human brain.”Mele is hopeful that other philosophers willbecome better acquainted with the science ofconscious intention. And where philosophy isconcerned, he says, scientists would do well tosoften their stance. “It’s not as though the taskof neuro scientists who work on free will has tobe to show there isn’t any.” ■Kerri Smith is editor of the Nature Podcast,and is based in London.1. Soon, C. S., Brass, M., Heinze, H.-J. & Haynes, J.-D.Nature Neurosci. 11, 543–545 (2008).2. Libet, B., Gleason, C. A., Wright, E. W. & Pearl, D. K.Brain 106, 623–642 (1983).3. Bode, S. et al. PLoS ONE 6, e21612 (2011).4. Fried, I., Mukamel, R. & Kreiman, G. Neuron 69,548–562 (2011).5. Vohs, K. D. & Schooler, J. W. Psychol. Sci. 19, 49–54(2008).1 SEPTEMBER 2011 | VOL 477 | NATURE | 25© 2011 Macmillan Publishers Limited. All rights reserved