The Libet experiment and its implications for conscious will implications for conscious will Peter G.H. Clarke Peter G.H. Clarke

Summary Summary A famous experiment of Benjamin Libet and his colleagues has been interpreted as showing that our initiateA famous voluntary experiment movements of Benjamin before Libetwe are and aware his colleaguesof having decidedhas been to interpretedmove, and asthat showing this calls that into our question brains theinitiate efficacy voluntary of our movements wills. These before claims we arehave aware been ofcontested having decidedby many to neuroscientistsmove, and that andthis philosophers.calls into question This paperthe efficacy provides of anour introduction wills. These to claimsthe controversy. have been contested by many neuroscientists and philosophers. This paper provides an introduction to the controversy.

The neurophysiological experiments of Benjamin Libet and his collaborators in the 1980s1 have been interpreted by the authors About the Author The neurophysiological experiments of Benjamin Libet and his Dr Peter Clarke was an associate professor at andcollaborators many others in the as 1980sshowing1 have that been our interpreted brains initiate by the conscious authors theAbout University the Author of Lausanne, Switzerland, until Dr Peter Clarke was an associate professor at voluntaryand many movementsothers as showing as well asthat the our will brains to move initiate before conscious we are 2012. He taught anatomy and neuroscience and consciously aware of the will to move. I shall refer to this claim didthe Universityresearch on of theLausanne, mechanisms Switzerland, of neuronal until voluntary movements as well as the will to move before we are 2012. He taught anatomy and neuroscience and asconsciously the Libet aware claim of for the brev willity. to Itmove. is controversial, I shall refer tobut this if claimvalid death. His main focus is now on the would have important implications for our understanding of how philosophicaldid research onimp thelications mechanisms of neuroscience. of neuronal He as the Libet claim for brevity. It is controversial, but if valid death. His main focus is now on the the mind relates to the and for the role of conscious will in is an associate editor of Science and Christian would have important implications for our understanding of how Beliefphilosophical and is a impmemberlications of The of neuroscience.Faraday Institute He the mindperformance relates toof the voluntary brain and actions. for the Before role of going conscious into willdetails in is an associate editor of Science and Christian about the Libet experiment, I must first provide some information Advisory Board. He is the author of Dieu, the performance of voluntary actions. Before going into details l’hommeBelief and et is le a cerveau member (Croire of The Pocket,Faraday 2012). Institute about the mind-brain relationship and the of about the Libet experiment, I must first provide some information Advisory Board. He is the author of Dieu, l’homme et le cerveau (Croire Pocket, 2012). voluntaryabout the movement.mind-brain relationship and the neurophysiology of We will have nothing to do with the fantastic suggestion, that voluntary movement. what the supersensitive ‘reactors’ in the cortex react to, is the The mindmind-brain-brain relationship and the Libet claim We will have nothing to do with the fantastic suggestion, that initiative of a virtually disembodied soul. To what, then, are It is generally accepted that the electrical activity of our brains what the supersensitive ‘reactors’ in the cortex react to, is the The mind-brain relationship and the Libet claim we to say that they do react? What else, than to the motions of underlies our conscious , including our decision making. initiative of a virtually disembodied soul. To what, then, are It is generally accepted that the electrical activity of our brains the embodied soul, that is to say, other motions in the same How a physical thing, the brain, can be the basis of we to say that they3 do react? What else, than to the motions of underlies our conscious thought, including our decision making. ? is a subject of debate that has given rise to many different the embodied soul, that is to say, other motions in the same How a physical thing, the brain, can be the basis of consciousness 3 philosophical positions, but these can be grouped in two main nervous system? is a subject of debate that has given rise to many different For these reasons, with a few exceptions,4 most modern categories:philosophical dualism positions, and monism.but these can be grouped in two main So great was the influence of Descartes on western philosophersFor andthese neuroscientists, reasons, with awhether few exceptions, theist or 4atheist,most modern accept categories: dualism and monism. some form of monism, but this does not have to involve eliminative philosophySo that, great from was the the late influence seventeenth of Descartes century untilon westernaround philosophers and neuroscientists, whether theist or atheist, accept 1950 or so, most westerners accepted some form of interactive materialismsome form of that monism, reject sbut mind this asdoes illusory. not have Many to involve theists, eliminative agnostics philosophy that, from the late seventeenth century until around and atheists adopt more moderate monist positions such as two- dualism,1950 or so,involving most westerners an immaterial accepted soul actingsome onform a material of interactive brabrain.in. materialism that rejects mind as illusory. Many theists, agnostics Since then this view has lost favour, for a variety of reasons, aspectand atheists monism adopt, according more moderate to which monist our subjective, positions firstsuch-personal, as two- dualism, involving an immaterial soul acting on a material brain. account of our inner life and neuroscience’s objective, third- includingSince then the this arguments view has of lost philosophers favour, for such a varietyas Ryle, of Place reasons, and aspect monism, according to which our subjective, first-personal, Feigl. In addition, atheistic materialists rejected it because it personal account of our brain’s activity refer to complementary including the arguments of philosophers such as Ryle, Place and account of our inner life5 and neuroscience’s objective, third- invokes a nonmaterial entity, but so did most Christian aspectspersonal of account a single of entity. our brain’s An alternative activity referview tois complementarythe mind-brain Feigl. In addition, atheistic materialists rejected it because it identity theory, according to5 which the mind and the brain’s activity acinvokesademics, a becausenonmaterial advances entity, in thebut analysis so did of biblicalmost Christian texts in aspects of a single entity. An alternative view is the mind-brain the mid twentieth century and since tended to support a monistic areidentity considered theory, toaccording be the sameto which entity, the notmind two and aspects the brain’s of the activity same academics, because advances in the analysis2 of biblical texts in conception of man, not a dualistic one. This realisation was not entity.are considered I prefer to two be -aspectthe same monism entity, becausenot two aspectsmind-brain of the identity same the mid twentieth century and since tended to support a monistic seems to me linguistically problematic, but the two formulations entirelyconception revolutionary, of man, not because a dualistic there one. had2 Thisalways realisation been a monistwas notic entity. I prefer two-aspect monism because mind-brain identity strand in Christian thought due to the influence of Thomas makeseems identical to me linguistically predictions at problematic, the level of brainbut thefunction. two formulations entirely revolutionary, because there had always been a monistic A striking aspect of the Libet claim is that it goes against Aquinas.strand in Thus,Christian during thought his Gifford due Lecturesto the influence in 1956- 57,of AnglicanThomas make identical predictions at the level of brain function. theologian Austin Farrer criticised the dualistic views of the main Aversions striking of aspect both dualismof the Libet and claimmonism. is that Cartesian it goes dualismagainst Aquinas. Thus, during his Gifford Lectures in 1956-57, Anglican predicts that mind events should precede brain events, since the neurobiologisttheologian Austin (and Farrerfuture criticisedNobel prize the-winner) dualistic John views Eccles, of the main versions of both dualism and monism. Cartesian dualism writing: nonphysicalpredicts that mind mind (or events soul etc.)should is considered precede brain to be events,the real sincesource the of neurobiologist (and future -winner) John Eccles, our decisions. TwoTwo-aspect-aspect monism and mindmind-brain-brain identity theory writing: nonphysical mind (or soul etc.) is considered to be the real source of bothour decisions. predict that Two-aspect mind and monism brain eventsand mind-brain should be identity synchronous theory, both predict that mind and brain events should be synchronous, 1 Libet, B., Gleason, C.A., Wright, E.W. & Pearl, D.K. ‘Time of conscious 3 Farrer, A. The Freedom of the Will, London: A & C Black (1958), p. 87. intention to act in relation to onset of cerebral activity (readiness-potential). 4 Goetz, S. and Taliaferro, C. A Brief History of the Soul, Chichester, UK: Wiley- 1 Libet, B., Gleason, C.A., Wright, E.W. & Pearl, D.K. ‘Time of conscious 3 Farrer, A. The Freedom of the Will, London: A & C Black (1958), p. 87. The unconscious initiation of a freely voluntary act’, Brain (1983)106: 623- Blackwell4 (2011). 642.intention to act in relation to onset of cerebral activity (readiness-potential). 5 Nagel,Goetz, S.T. andThe Taliaferro, View From C. Nowhere A Brief History, Oxford: of theOxford Soul ,UniversityChichester, Press UK: (1986),Wiley- 2The unconscious initiation of a freely voluntary act’, Brain (1983)106: 623- Blackwell (2011). Green, J.B. Body, Soul and Human Life: The Nature of Humanity in the chap.5 3, p. 28; Jeeves, M. & Brown, W.S. Neuroscience, Psychology and Bible642. , Carlisle: Paternoster (2008). ReligionNagel, ,T. West The Conshohocken, View From Nowhere PA: Templeton, Oxford: FoundationOxford University Press (2009). Press (1986), 2 Green, J.B. Body, Soul and Human Life: The Nature of Humanity in the chap. 3, p. 28; Jeeves, M. & Brown, W.S. Neuroscience, Psychology and Bible, Carlisle: Paternoster (2008). Religion, West Conshohocken, PA: Templeton Foundation Press (2009). FARADAY PAPER 17 FARADAY PAPER 17 since mind-level descriptions and brain-level descriptions are much as a second earlier for simple movements and even longer for consideredsince mind-level complementary descriptions (and and equally brain-level valid) descriptionsaccounts of theare complexmuch as aseries second of earliermovements. for simple8 This movements electrical changeand even is longercalled thefor sameconsidered processes. complementary But if brain (andevents equally come first,valid) this accounts would support of the complexreadiness seriespotential of movements.(RP). 8 This electrical change is called the epiphenomenalismsame processes. But, theif brain view events that comemind first, events this wouldare mere support by- readiness Libetpotential was (RP). interested in the relative timing of the RP productsepiphenomenalism of brain ,events, the view with thatno causalmind role.events This are would mere deny by- comparedLibet with thewas movement interested andin thethe consciousrelative timing decision of tothe move. RP theproducts causal of efficacy brain events,of conscious with nowill. causal role. This would deny Hecompared therefore with asked the movement his experimental and the conscioussubjects to decision perform to simplemove. the causal efficacy of conscious will. movements,He therefore inasked most hiscases experimental flexion of thesubjects fingers to orperform wrist, simpleand to The neurophysiology of voluntary movement estimatemovements, the intime most of casesconscious flexion awareness of the fingersof the urgeor wrist, (or willand orto ItThe is importantneurophysiology to be clear of voluntaryabout what movement is, and is not, being claimed decision)estimate theto movetime (W)of conscious by reporting awareness the position of the of aurge spot (or moving will orin whenIt is important a movement to be clearis calledabout whatvoluntary. is, and isEven not, beingthough claimed these adecision) circle on to anmove oscilloscope (W) by reporting screen. theThey position were toldof a spotto perform moving the in movementswhen a movement involve, byis definition,called voluntary. an act of consciousEven though will, thatthese is movementa circle on wheneveran oscilloscope they feltscreen. like They doing were so, toldand to to perform pay close the notmovements to say thatinvolve, every by aspectdefinition, of the an actmovement of conscious is conscious will, that oris attentionmovement to wheneverthe time whenthey feltthey likewere doing first awareso, and of tothe pay ‘urge close to willed.not to sayFor thatexample, every theaspect movements of the movement of a tennis is playerconscious as she or move’. He to also the recorded time when the RPthey by were , first aware of the ‘urge and theto serveswilled. areFor voluntary, example, butthe theirmovements control ofinvolves a tennis many player automatic as she timemove’. ofHe alsothe recordedmovement the RPitself by electroencephalography, was estimated from an d the subroutinesserves are voluntary, in the cerebellum but their controland elsewhere. involves manyFurthermore, automatic to electromyogram.time of the movementLibet found itselfthat timewas W estimatedcame only fromabout 200the claimsubroutines that conscious in the cerebellum acts of will and initiate elsewhere. voluntary Furthermore, movements tois msecelectromyogram. before the movement,Libet found whereas that time the W RP came began only much about earlier, 200 notclaim to thatdeny conscious that the actsacts ofof willwill ariseinitiate out voluntary of brain processesmovements that is usuallymsec before about the550 movement, msec before whereas the movement the RP (Fig.began 2). much The fact earlier, that arenot largelyto deny unconscious. that the acts6 of will arise out of brain processes that theusually change about in brain550 msec potential before occurred the movement before the (Fig. conscious 2). The decisionfact that are largelyWhat unconscious. is the nature6 of the ‘I’ (or self) that willed the wasthe change interpreted in brain by Libetpotential and occurred by many before commentators the conscious to imply decision that movementWhat and isperformed the nature it? of The the use‘I’ (orof suchself) termsthat willed does notthe ourwas consciousinterpreted decision by Libet to andact isby not many the truecommentators cause of the to movement.imply that implymovement dualism. and performedThe ‘I’ (orit? self,The useor mindof such etc.) terms is generallydoes not Theyour conscious deduced decision that conscious to act is notwill the is truetoo causeslow ofto the make movement. things conceivedimply dualism. as being The embodied ‘I’ (or inself, (or oremerging mind etc.)from) is the generally brain’s happen,They deduced and that that volitional conscious acts will must is tooresult slow from to makeunconscious things activity.conceived as being embodied in (or emerging from) the brain’s processeshappen, and in thethat brain, volitional not from acts conscious must result willing. from This unconscious seemed to activity. The neural circuits involved in voluntary motor control implyprocesses that inour the intuitive brain, notionnot from of conscious willwilling. must This be an seemed illusion. to are exceedinglyThe neural complicated, circuits involved and inI voluntaryhere give motor only controlsome imply that our intuitive notion of conscious will must be an illusion. simplifiedare exceedingly information complicated, that is necessaryand I here for understandinggive only some the Libetsimplified experiment. information Voluntary that ismovements necessary are for controlled understanding primarily the byLibet the experiment. motor cortex Voluntary (in the back movements part of the are frontal controlled lobe primarily– Fig. 1) butby thein cooperationmotor cortex with (in themany back other part motorof the centresfrontal lobeincluding – Fig. the 1) basalbut in ganglia cooperation and the with cerebellum. many other Motor motor commands centres includingare sent from the thebasal primary ganglia motor and the cortex cerebellum. (and to some Motor extent commands from other are sent areas) from to motoneuronsthe primary motor in the cortex brainstem (and to andsome spinal extent cord, from whichother areas) in turn to controlmotoneurons the inmuscles. the brainstem The initiation and spinal and cord, programming which in turnof movementscontrol the dependmuscles. on Theactivity initiation in many and areas programming including theof supplementarymovements depend motor onarea activity (l) and inthe manypreSMA, areas and including several areas the insupplementary the parietal cortex.motor areaThese (l) areas and thefeed preSMA, directly andor indirectly several areas into thein the premotor parietal cortexcortex. and These motor areas cortex. feed directlyElectrical or stimulationindirectly into of the motorpremotor areas cortex produces and movements,motor cortex. but Electrical not the will stimulation to move. ofIn contrast,the motor electrical areas produces stimulation movements, of areas but BA-39 not the and will BA-40 to move. in the In parietalcontrast, lobe electrical (Fig. 1)stimulation elicits the ofwill areas to move, BA-39 but and does BA-40 not cause in the a movement.parietal lobe7 (Fig. 1) elicits the will to move, but does not cause a Fig. 2. Schematised readiness potentials (RPs) preceding self-initiated movement.7 Fig.voluntary 2. Schematised acts, as in readinessthe Libet potentialsexperiment. (RPs) Since preceding these scalp-recorded self-initiated voluntarypotentials acts,are of as only in theabout Libet 10 experiment.μV, smaller Sincethan the these background scalp-recorded EEG, potentialsthe experimenters are of only had about to average 10 μV, aboutsmaller 40 than raw therecordings background to obtEEG,ain thereproducible experimenters results. had We to follow average Libet about et al. 40 in raw using recordings the term to‘Time obt ainof reproducibleawareness of results.urge to move’We follow and inLibet designating et al. in itusing by W the (for term will). ‘Time of awareness of urge to move’ and in designating it by W (for will).

There appeared to be a small loophole in that Libet’s subjects stillThere had appeared the power to tobe vetoa small a movement loophole in in the that 200 Libet’s msec betweensubjects stilltime hadW andthe thepower movement. to veto Hea movement therefore arguedin the 200that mseceven thoughbetween thetime initiation W and the of movement. the movement He therefore was not argued the thatresult even of consciousthough the will, initiation its vetoing of the was. movement This argument was nothas thenot resultattracted of consciousgreat interest, will, but its was vetoing supported was. byThis eminent argument free-will has not philosopher attracted Robertgreat interest, Kane.9 but was supported by eminent free-will philosopher Robert Kane.The 9Libet experiment provoked considerable interest and intense controversy,The Libet experimentand stimulated provoked further considerableexperimentation. interest and Fig. 1. The brain’s , viewed from the right side. SMA: intense controversy, and stimulated further experimentation. supplementaryFig. 1. The brain’s motor cerebral area. BA:cortex, Brodmann’s viewed from area the. right side. SMA: Single neuron recordings during the Libet experiment supplementary motor area. BA: Brodmann’s area. ItSingle is rarely neuron possible recordings to record during from the single Libet neurons experiment in the brains of The Libet experiment, a challenge to the role of conscious will humans,It is rarely but possible this can tooccasionally record from be singledone inneurons epilepsy in patientsthe brains using of AnThe importantLibet experiment, background a challenge to the toLibet the roleexperiment of conscious was willthe electrodeshumans, but that this have can beenoccasionally implanted be todone localise in epilepsy the zones patients that causeusing discoveryAn important in the background 1960s that, to beforethe Libet people experiment make a voluntarywas the seizures.electrodes Thus,that have remarkably, been implanted Itzhak to Fried localise and the his zones collaborators that cause movement,discovery in there the 1960sis a slowthat, beforebuild-up people of electricalmake a voluntarypotential managedseizures. toThus, record remarkably, from more Itzhak than 1,000Fried neuronsand his incollaborators the medial measuredmovement, from there the is skull a slow over build-upthe motor of cortex, electrical beginning potential as managed to record from more than 1,000 neurons in the medial measured from the skull over the motor cortex, beginning as 8 Kornhuber, H.H. and Deecke, L. ‘Hirnpotentialänderungen bei 6 Gomes, G. ‘The timing of conscious experience: a critical review and Willkürbewegungen8 Kornhuber, H.H. undand passivenDeecke, L.Bewegungen ‘Hirnpotentialänderungen des Menschen: bei 6reinterpretationGomes, G. ‘The of Libet'stiming research’,of conscious Consciousness experience: & a Cognitioncritical review(1998) and 7: WillkürbewegungenBereitschaftspotential undund reafferente passiven Potentiale‘, Bewegungen Pflügers Archivdes (1965)Menschen: 284: 1- 559reinterpretation-595. of Libet's research’, Consciousness & (1998) 7: Bereitschaftspotential17. und reafferente Potentiale‘, Pflügers Archiv(1965) 284: 1- 7 9 559 Desmurget,-595. M., Reilly, K.T., et al. ‘Movement intention after parietal cortex 17.Kane, R. The Significance of , New York / Oxford: Oxford University 7stimulation Desmurget, in M., humans’, Reilly, Science K.T., et(2009) al. ‘Movement 324, 811 -intention813. after parietal cortex Press9 Kane, (1996), R. The p. Significance 232. of Free Will, New York / Oxford: Oxford University stimulation in humans’, Science (2009) 324, 811-813. 2 Press (1996), p. 232. 2 frontal cortex of epilepsy patients (and especially in the before it enters awareness’.17 After all the subtle debate about a few supplementaryfrontal cortex motorof epilepsy area, which patients generates (and most especially of the early in partthe beforehundreds it entersof milliseconds, awareness’. 1017 Aftersec was all anthe enormous subtle debate amount about of atime, few ofsupplementary the RP) as they motor performed area, which the generatesLibet experiment. most of theIt was early found part andhundreds the wordingof milliseconds, of the 10abstract sec was gave an enormousthe impression amount thatof time, the thatof the a fewRP) neuronsas they performedchanged their the Libetfiring experiment.rate (by an increaseIt was found or a temporaland the wordingpriority ofof thethe abstractneural decisiongave the withimpression respect thatto thethe decrease)that a few almostneurons 1.5 changed secs before their firingtime rateW, and(by anmore increase and more or a subjectivetemporal priorityone was of finallythe neural established. decision I withassume respect that tosome the neuronsdecrease) did almost so over 1.5 the secs following before 1.5time secs, W, with and aboutmore 25% and ofmore the journalistssubjective andone bloggerswas finally only hadestablished. access to Ithe assume abstract that (available some neurons didfiring so severalover the tenths following of a 1.5second secs, before with about W. The 25% authors of the freejournalists on the and web) bloggers and not only to thehad full access paper, to becausethe abstract the (availablemain text concludeneurons firing that theirseveral findings tenths support of a second the view before that W. the The experience authors madefree on only the the web) much and weaker not to claim the full that paper, the activity because of prefrontthe mainal textand ofconclude will emerges that their as findingsthe culmination support ofthe premotor view that activity the experience starting parietalmade only cortex the muchwas correlated weaker claim with that the the decision activity(to of useprefront the leftal and or severalof will hundredsemerges asof themsecs culmination before awareness. of premotor10 activity starting parietalright hand) cortex with was 60% correlated prediction with accuracy, the decision up to (to10 usesec beforethe left the or several hundreds of msecs before awareness.10 consciousright hand) decision. with 60% That prediction is very accuracy, different! up Toto 10reflect sec before a neural the Criticisms of the Libet claim decisionconscious, thedecision. correlation That would is very need different! to be at 100%To reflect, not 60%.a neural The DespiteCriticisms the of famethe Libet of theclaim Libet experiment and its frequent decisionpaper provided, the correlation valuable wouldinformation need toabout be at brain 100% activity, not 60%. leading The acceptanceDespite the in famepopular of andthe semi-popularLibet experiment writings, and it hasits beenfrequent the ultimatelypaper provided to a valuabledecision, information but did nothing about brainto rescue activity the leading Libet subjectacceptance of intensein popular controversy. and semi-popular Indeed, writings,most specialists it has been in the experimentultimately tofrom a thedecision, criticisms but about did timing.nothing to rescue the Libet philosophysubject of intenseof free willcontroversy. who have Indeed, addressed most the specialistsLibet claim in have the experimentThe from overall the criticisms conclusion about on timing. timing has to be that the rejectedphilosophy it. 11of Mostfree willof thewho criticisms have addressed focused the on Libet difficulties claim have of problems Thehave overallnot so farconclusion been resolved. on timing has to be that the rejectedjudging theit. 11 timeMost of of awareness, the criticisms of interpretingfocused on thedifficulties RP, or of problems have not so far been resolved. philosophicaljudging the time interpretation, of awareness, as is discussedof interpreting below. the RP, or of Doubts as to whether the readiness potential reflects a decision to philosophical interpretation, as is discussed below. moveDoubts as to whether the readiness potential reflects a decision to Problems of judging the time of awareness Themove Libet claim assumes that the RP reflects a neural ‘decision’ to ItProblems was central of judging to Libet’s the timeclaim of thatawareness the readiness potential began move,The Libet and claimthat the assumes neural activitythat the underlyingRP reflects the a neural RP causes ‘decision’ both the to distinctlyIt was central before to timeLibet’s W. claimThe published that the readinessdata of several potential groups began do willmove, to and move that and the theneural movement. activity underlying Even if such the RPcausality causes could both thebe indeeddistinctly support before this time claim, W. The but published critics have data objected of several to thegroups use doof demonstrated,will to move andthis thewould movement. not strictly Even be if sufficient such causality to validate could thebe subjectiveindeed support recall this after claim, the butevent, critics because have thereobjected is evidenceto the use that of Libetdemonstrated, claim, because this would the decision not strictly must be presumably sufficient beto causedvalidate by the a thissubjective can be recall very afterunreliable. the event, Furthermore, because therethose issuch evidence as Alfred that chainLibet claim,of preceding because neural the decision events, andmust the presumably RP might bereflect caused some by of a Melethis can12 who be havevery triedunreliable. the experiment Furthermore, for themselves those such have as Alfredfound these.chain ofBut preceding the Libet neural claim events, certainly and assumes the RP causality.might reflect This some is part of Melethat W12 whois difficult have tried to define. the experiment I have done for themselvesthis too, and have you found may ofthese. the claim,But the and Libet it has claim never certainly been proved. assumes causality. This is part wishthat W to istry difficult it using to a define.‘clock’ Iavailable have done on thisthe web.too, 13andWhen you Imay try of the claim,To beand precise, it has never we are been really proved. talking about the earliest part wishthis, Ito find try itit veryusing hard a ‘clock’ to judge available the precise on the time web. when13 When I decided I try of the RP,To because be precise, the timingwe are argumentreally talking focuses about on thethe earliestRP’s onset. part tothis, move I find my it veryfinger/wrist. hard to judge It would the precise be useful time towhen quantify I decided the Toof theattribute RP, because such a decisionalthe timing andargument causal focusesrole to thison theearliest RP’s part onset. of reliabilityto move myof ourfinger/wrist. judgements, It wouldbut this be is useful difficult to forquantify a purely the theTo attributeRP seems such surprising, a decisional because and causalit originates role to mainlythis earliest in the part SMA of subjectivereliability decision.of our judgements, For this reason, but thisseveral is difficultresearch forgroups a purely have (Fig.the RP 1), seems which surprising, has been becauseknown forit originates more than mainly thirty inyears the SMAto be insteadsubjective measured decision. theFor thisreliability reason, severalof timing research judgements groups havefor strongly(Fig. 1), activatedwhich has when been subjects known ‘programme’ for more than (imagine) thirty years a complex to be perceptualinstead measuredevents, thewhich reliability is easier ofto timingdo. Results judgements have beenfor movementstrongly activated without when actually subjects performing ‘programme’ it.18 This (imagine) is not to a denycomplex that variable,perceptual butevents, several whichgroups isfound easier serious to do. biases, Results14 raising have doubts been activitymovement in SMAwithout can actually cause movements performing in it. some18 This cases, is not such to deny as when that variable,about the but interpretation several groups of foundthe Libet serious experiment. biases,14 raising A different doubts itactivity is stimulated in SMA electrically, can cause movementsbut it cannot in be some assumed cases, that such the as earliest when critiqueabout the of interpretationthe timing was of madethe Libetby Dennett experiment. and Kinsbourne, A different15 partit is stimulatedof the RP electrically, necessarily butreflects it cannot neural be assumedprocesses that underlying the earliest a whocritique point of outthe thattiming Libet’s was experimentmade by Dennett involves and an Kinsbourne,attention shift15 decisipart ofon the to move.RP necessarily And there reflectsare at least neural six specificprocesses reasons underlying to doubt a fromwho pointthe participants’out that Libet’s subjective experiment intention involves to thean attentionclock, which shift this.decision to move. And there are at least six specific reasons to doubt mayfrom havethe participants’ introduced subjectivetemporal mismatchesintention to betweenthe clock, the which felt this. First, even though electrical stimulation of the SMA can experiencemay have ofintroduced will and thetemporal perceived mismatches position of betweenthe clock thehand. felt cause movements,First, even it thoughdoes not electrical cause a willstimulation to move, of which the SMA requires can experienceTo of try will to andsolve the these perceived problems, position Matsuhashi of the clock and hand. Hallett stimulationcause movements, of parietal it does areas. not19 causeThis asuggests will to move,that the which RP doesrequiresnot devised anTo alternative try to solve methodology these problems, for estimating Matsuhashi time and W. Hallett They stimulationcause the will of toparietal move. areas.19 This suggests that the RP does not founddevised that an thealternative RP (which methodology they called for BP1) estimating occurred time before W. TheyW in cause the Second,will to move. if the RP truly caused the conscious will and the onlyfound about that thetwo RP thirds (which of thethey subjects; called BP1) worse, occurred the lateralised before W RP in movement,Second, one would if the expect RP truly trial- causedto-trial the variations conscious in willthe onsetand the of (LRP)only about that wetwo shall thirds discuss of the below, subjects; always worse, occurred the lateralisedafter W.16 RP movement,the RP to correlate one would with expect trial-to trial--trialto variations-trial variations in time in W;the thatonset is ofto (LRP) thatIn we view shall of discuss the controversy below, always about occurred the measurement after W.16 of saythe RPthat to trialscorrelate with with an trial-earlyto RP-trial should variations also in have time anW; earlythat is W. to subjectiveIn timing,view of considerable the controversy attention about wasthe measurementdevoted in theof Haggardsay that trialsand Eimerwith antested early this,RP shouldusing aalso variant have ofan theearly Libet W. publicsubjective media timing, to a paperconsiderable published attention in Nature was Neuroscience devoted in thatthe experiment,Haggard and and Eimer found testedthere wasthis, little using correlation, a variant ruling of outthe theLibet RP usedpublic brain media scanning to a paper technology published (functional in Nature magnetic Neuroscience resonance that asexperiment, a cause of and the found will or there decision was littleto move. correlation, They did, ruling however, out the find RP imagingused brain – scanningfMRI) in technology a Libet-like (functional experimental magnetic paradigm, resonance and thatas a thecause ‘lateralized of the will readiness or decision potential’ to move. (LRP: They i.e did,. the however, RP from find the imagingincluded in– thefMRI) summary in a Libet-likea claim that experimental a ‘decision canparadigm, be encoded and cortexthat the on ‘lateralized the opposite readiness side relative potential’ to the (LRP: movement i.e. the minus RP from the RPthe inincluded brain activityin the summary of prefrontal a claim and that parietal a ‘decision cortex can almost be encoded 10 sec fromcortex the on same the opposite side) gave side a relativepositive tocorrelation, the movement suggesting minus thatthe RPthe in brain activity of prefrontal and parietal cortex almost 10 sec brainfrom theprocesses same side)underlying gave a the positive LRP mightcorrelation, cause suggestingthe will to move.that the20 20 Atbrain the processes time, their underlying paper did the not LRP seem might to challenge cause the the will Libet to move. claim, 10 At the time, their paper did not seem to challenge the Libet claim, Fried, I., Mukamel, R. & Kreiman, G. ‘Internally generated preactivation of because the LRP seemed to fulfil the role formerly attributed to the 10singleFried, neurons I., Mukamel, in human R. & medialKreiman, frontal G. ‘Internally cortex predicts generated ’, preactivation Neuronof RP.because However, the LRP the seemed LRP occursto fulfil later the rolethan formerlythe RP, attributedand subsequent to the single(2011) neurons69: 548- 562.in human medial frontal cortex predicts volition’, Neuron experimentsRP. However, havehave the sometimes sometimesLRP occurs foundfound later that that than the the theLRP LRP RP, occurs occurs and even subsequent even after after 11 (2011)Bayne, 69: T. 548 ‘Libet-562. and the case for free will scepticism’, in Swinburne, R. experiments have sometimes found that the LRP occurs even after (ed.)11 Bayne, Free T.Will ‘Libet and Modernand the Sciencecase for, Oxford:free will Oxford scepticism’, University in Swinburne, Press (2011). R. 12 (ed.)Mele Free, A. Will R. Effectiveand Modern Intentions: Science ,The Oxford: Power Oxford of Conscious University Will Press,New (2011). York / 12Oxford:Mele, OxfordA. R. Effective University Intentions: Press (2009). The Power of Conscious Will,New York / 13 17 Oxford:There Oxfordis a suitable University clock atPress (2009). Soon, C.S., Brass, M., Heinze, H.J. & Haynes, J.D. ‘Unconscious determinants 13http://www.informationphilosopher.com/freedom/libet_experiments.htmlThere is a suitable clock at 17of Soon,free decisions C.S., Brass, in the M., human Heinze, brain’, H.J. Nature& Haynes, Neuroscience J.D. ‘Unconscious(2008) 11: determinants 543-545. 14 18 http://www.informationphilosopher.com/freedom/libet_experiments.htmlDanquah, A.N., Farrell, M.J. & O'Boyle, D.J. ‘Biases in the subjective of Roland,free decisions P.E., Larsen,in the human B., Lassen, brain’, NatureN.A. & NeuroscienceSkinhoj, E. ‘Supplementary(2008) 11: 543 -motor545. 14timingDanquah, of perceptual A.N., Farrell, events: M.J. Libet & etO'Boyle, al. (1983) D.J. revisited’, ‘Biases Consciousnessin the subjective & 18areaRoland, and other P.E., cortical Larsen, areas B., Lassen,in organization N.A. & Skinhojof voluntary, E. ‘Supplementary movements in motorman’, Cognitiontiming of perceptual(2008) 17: 616events:-627. Libet et al. (1983) revisited’, Consciousness & areaJournal and of other Neurophysiology cortical areas(1980) in organization 43: 118-136. of voluntary movements in man’, 15 19 CognitionDennett, (2008)D.C. & 17: Kinsbourne, 616-627. M. ‘Time and the observer’, Behavioral and JournalDesmurget of Neurophysiology et al. op. cit., (7).(1980) 43: 118-136. 20 Brain15Dennett, Sciences D.C.(1992) & Kinsbourne, 15: 183– 247.M. ‘Time and the observer’, Behavioral and 19 DesmurgetHaggard P. et & al. Eimer op. cit. M., (7). ‘On the relation between brain potentials and the 16 BrainMatsuhashi Sciences M.(1992) & Hallett, 15: 183 –M.247. ‘The timing of the conscious intention to awareness20 Haggard ofP. voluntary& Eimer movements’M. ‘On the, Experimentalrelation between Brain brain Research potentials(1999) and 126: the move’,16 Matsuhashi European M. Journal& Hallett, of Neuroscience M. ‘The timing(2008) of 28:the 2344conscious-2351. intention to awareness128-133. of voluntary movements’, Experimental Brain Research (1999) 126: move’, European Journal of Neuroscience (2008) 28: 2344-2351. 3 128-133. 3 21 time W as is discussed above,21 so the LRP seems a fragile irrelevant to the question of free will. When we talk about free will, time W as is discussed above, so the LRP seems a fragile irrelevant to the question of free will. When we talk about free will, candidatetime W as to isreplace discussed the RP. above, 21 so the LRP seems a fragile weirrelevant are usually to the referring question to of choices free will. among When a varietywe talk of about options, free oftenwill, candidate to replace the RP. we are usually referring to choices among a variety of options, often candidateThird, to replace Alfred the RP.Mele has pointed out a flaw in Libet’s withwe are moral usually implications, referring to and choices this amongmay require a variety careful of options, deliberation often Third, Alfred Mele has pointed out a flaw in Libet’s with moral implications, and this may require careful deliberation experimentalThird, paradigm Alfred thatMele vitiates has pointed attempts out to a deduceflaw in a Libet’scausal overwith amoral period implications, of minutes orand hours this ormay days. require The carefulLibet experiment deliberation is experimental paradigm that vitiates attempts to deduce a causal over a period of minutes or hours or days. The Libet experiment is influenceexperimental between paradigm the RPthat andvitiates the attemptsmovement to (anddeduce the a willcausal to justover the a period opposite. of minutesThe subject or hours was notor days.making The a moralLibet experimentdecision, and is influence22 between the RP and the movement (and the will to just the opposite. The subject was not making a moral decision, and move).influence22 Inbetween all Libe thet’s RPexperiments, and the movement the permanent (and thestorage will ofto wasjust thenot opposite.even deciding The subject whether was to notmove, making but onlya moral when decision,. Moreover, and move). In all Libet’s experiments, the permanent storage of was not even deciding whether to move, but only when. Moreover, electroencephalographicmove).22 In all Libet’s experiments,data was triggered the permanent by the finger/wriststorage of thewas subjectsnot even were deciding specifically whether instructed to move, not but toonly deliberate when. Moreover,but to act electroencephalographic data was triggered by the finger/wrist the subjects were specifically instructed not to deliberate but to act movements.electroencephalographic This was datanecessary was triggeredas part byof thethe finger/wristaveraging spontaneously,the subjects were and specifically in their original instructed 1983 notpaper to Libetdeliberate et al. butexplicitly to act movements. This was necessary as part of the averaging spontaneously, and in their original 1983 paper Libet et al. explicitly proceduremovements. that This is necessarywas necessary to detect as partthe RP,of thewhich averaging would pointedspontaneously, out that and their in their conclusions original 1983 applied paper only Libet to et spontaneous,al. explicitly procedure that is necessary to detect the RP, which would pointed out that their conclusions27 applied only to spontaneous, otherwiseprocedure bethat masked is necessary by other toconcurrent detect theactivity RP, inwhich the EEG. would If rapidlypointed performedout that their movements. conclusions27 Thus, applied even only if towe spontaneous, accept the otherwise be masked by other concurrent activity in the EEG. If rapidly performed movements. Thus, even if we accept the thereotherwise was nobe movement,masked by theother data concurrent were not activitystored, so in anythe RPsEEG. that If rapidlydebatable performed claim that movements. the finger/wrist27 Thus, movementseven if we in acceptthe Libet the there was no movement, the data were not stored, so any RPs that debatable claim that the finger/wrist movements in the Libet occurredthere was withoutno movement, being followedthe data wereby movements not stored, wouldso any notRPs have that experimentdebatable claimwere notthat thethe result finger/wrist of conscious movements will, this in conclusionthe Libet occurred without being followed by movements would not have experiment were not the result of conscious will, this conclusion beenoccurred detected. without If beingsuch RPsfollowed without by movementsmovement didwould occur, not havethen cannotexperiment automatically were not bethe extended result of toconscious situations will, for whichthis conclusion the term been detected. If such RPs without movement did occur, then cannot automatically be extended to situations for which the term RPsbeen aredetected. not sufficient If such toRPs cause without movements, movement and did more occur, probably then freecannot will automatically would normally be beextended applied. to situations for which the term RPs are not sufficient to cause movements, and more probably free will would normally be applied. reflectedRPs are notbrain sufficient activity tooccurring cause movements, prior to the and decision more toprobably move. free will wouldAnother normally problem be isapplied. that those who support an anti-free- reflected brain activity occurring prior to the decision to move. Another problem is that those who support an anti-free- Thisreflected possibility brain activity is difficult occurring to evaluate, prior to becausethe decision the averagingto move. will interpretationAnother problemappear tois thathave those in mind who onlysupport rather an anti-free-marginal This possibility is difficult to evaluate, because the averaging will interpretation appear to have in mind only rather marginal procedureThis possibility has tois bedifficult triggered to evaluate, at a moment because defined the averaging by the notionswill interpretation of free will. appearFor example, to have in ain review mind ononly the ratherneuroscience marginal of procedure has to be triggered at a moment defined by the notions of free will. For example, in a review on the neuroscience of movement.procedure has to be triggered at a moment defined by the volition,notions of neurobiologist free will. For Haggard,example, ain former a review collaborator on the neuroscience of Libet and of movement. volition, neurobiologist Haggard, a former collaborator of Libet and movement.Fourth, experiments by Hermann et al. cast further leadingvolition, protagonist neurobiologist of the Haggard, anti-free-will a former interpretation, collaborator mentionsof Libet andthe Fourth, experiments by Hermann et al. cast further leading protagonist of the anti-free-will interpretation, mentions the doubt on Fourth,the interpretation experiments of theby RPHermann as causally et al. related cast furtherto the possibilityleading protagonist that the ofbrain’s the anti-free-will circuits might interpretation, be influenced mentions by ‘anthe doubt on the interpretation23 of the RP as causally related to the possibility that the brain’s circuits might be influenced by ‘an decisiondoubt on andthe interpretationmovement.23 ofThese the RPresearchers as causally used related a modified to the unspecifiedpossibility thatand theuncaused brain’s cause circuits (the might“will”)’. be Haggard influenced rejects by this‘an decision and movement. These researchers used a modified unspecified and uncaused cause (the “will”)’. Haggard rejects this decisionversion ofand the movement. Libet experimental23 These researchers paradigm, used in awhich modified the view,unspecified and concludes and uncaused the article cause by (the stating “will”)’. that ‘modern Haggard neuroscience rejects this version of the Libet experimental paradigm, in which the view, and concludes the article by stating that ‘modern neuroscience participantsversion of thewere Libet instructed experimental to press paradigm, one of intwo which buttons, the isview, shifting and concludes towards thea view article of by voluntary stating that action ‘modern being neuroscience based on participants were instructed to press one of two buttons, is shifting towards a view of28 voluntary action being based on dependingparticipants on were a presented instructed stimulus. to press An RP one occurred of two well buttons, before specificis shifting brain towards processes…’. a view of28 Thisvoluntary gives action the impressionbeing based thaton depending on a presented stimulus. An RP occurred well before specific brain processes…’. This gives the impression that thedepending motor response,on a presented as in thestimulus. Libet experiment. An RP occurred But, importantly,well before ‘modernspecific neuroscience’brain processes…’. is gradually28 This triumphing gives the against impression the illusion that the motor response, as in the Libet experiment. But, importantly, ‘modern neuroscience’ is gradually triumphing against the illusion itthe occurred motor response, even before as inthe the stimulus Libet experiment. presentation, But, so itimportantly, clearly did of‘modern free will, neuroscience’ but this is confusing is gradually for triumphingat least two againstreasons. the First, illusion only it occurred even before the stimulus presentation, so it clearly did of free will, but this is confusing for at least two reasons. First, only notit occurred reflect evena decision before as the to stimulus which buttonpresentation, to press. so itThe clearly authors did aof tiny free minoritywill, but ofthis modern is confusing philosophers for at least conceive two reasons. of the First,will as only an not reflect a decision as to which button to press. The authors a tiny minority of modern philosophers conceive of the will as an arguenot reflect that thea decision RP does asnot to specifically which button determine to press. the The movement, authors ‘uncauseda tiny minority cause’, of somodern why usephilosophers such a mar conceiveginal definition? of the will Second, as an argue that the RP does not specifically determine the movement, ‘uncaused cause’, so why use such a marginal definition? Second, butargue may that reflect the RP a generaldoes not expectation specifically (which determine is indeed the movement, what the the‘uncaused words aboutcause’, modern so why neuroscience’s use such a mar ‘shiftingginal definition? towards a Second,view of but may reflect a general expectation (which is indeed what the the words about modern neuroscience’s ‘shifting towards a view of RPbut wasmay initially reflect athought general by expectation Kornhuber (whichand Deecke is indeed to reflect, what notthe voluntarythe words aboutaction modern being neuroscience’sbased on specific ‘shifting brain towards processes’ a view are of RP was initially thought by Kornhuber and Deecke to reflect, not voluntary action being based on specific brain processes’ are aRP decision was initially but a statethought of readiness, by Kornhuber hence and its name).Deecke to reflect, not strange,voluntary because action this being has beenbased the on standard specific view brain in neuroscience processes’ arefor a decision but a state of readiness, hence its name). strange, because this has been the standard view in neuroscience for a decisionFifth, but a Trevenastate of readiness,and Miller hence devised its name).a modified version of overstrange, half because a century. this hasIn thebeen same the standardreview, viewHaggard in neuroscience states that thefor Fifth, Trevena and Miller devised a modified version of over half a century. In the same review, Haggard states that the the LibetFifth, experiment Trevena in and which Miller participants devised a modifiedmade spontaneous version of Libetover halfexperiment a century. ‘seems In theto disprovesame review, the everyday Haggard concept states ofthat “free the the Libet experiment in which participants made spontaneous Libet experiment ‘seems to disprove the everyday concept of “free decisionsthe Libet toexperiment move, or not,in whichand found participants that the RPmade was spontaneous no stronger will”’;Libet experiment his reference ‘seems to to ‘everydaydisprove theconcept’ everyday suggests concept ofthat “free he decisions to move, or not, and found that the RP was no stronger will”’; his reference to ‘everyday concept’ suggests that he beforedecisions a decisionto move, toor movenot, and than found before that a thedecision RP was not no to stronger move, recogniseswill”’; his that reference this challenge to ‘everyday does not extendconcept’ to moresuggests sophisticated that he before a decision to move than before a decision not to move, recognises that this challenge does not extend to more sophisticated whichbefore isa notdecision what toone move would than expect before if thea decision RP reflected not to a neuralmove, conceptsrecognises of that free this will. challenge does not extend to more sophisticated which is not what24 one would expect if the RP reflected a neural concepts of free will. decisionwhich is tonot move. what24 one would expect if the RP reflected a neural concepts of free will. decision to move. decision toSixth, move. computational24 analysis suggests that the neural Conclusion Sixth, computational analysis suggests that the neural Conclusion decision toSixth, move computational occurs only very analysis late duringsuggests the thattime-course the neural of Libet’sConclusion 1983 experiment reported that brain activity (the RP) decision to move occurs 25 only very late during the time-course of Libet’s 1983 experiment reported that brain activity (the RP) thedecision RP, not to moveat its onset. occurs 25 only very late during the time-course of reflectingLibet’s 1983 a decision experiment to flexreported a finger that or brain wrist activityoccurred (the several RP) the RP, not at its onset. reflecting a decision to flex a finger or wrist occurred several the RP, not at its onset. 25 hundredreflecting millisecondsa decision tobefore flex athe finger subject or wristbecame occurred aware severalof her hundred milliseconds before the subject became aware of her Debate about the philosophical interpretation decisionhundred milliseconds(or urge or will)before to themove. subject This becamehas been aware interpreted, of her Debate about the philosophical interpretation decision (or urge or will) to move. This has been interpreted, EvenDebate if theabout Libet the claim philosophical is accepted interpretation – which is very controversial, controversially,decision (or urge to suggestor will) thatto move.our subjective This has impression been interpreted, that our Even if the Libet claim is accepted – which is very controversial, controversially, to suggest that our subjective impression that our asEven we if have the Libetseen claim– there is acceptedis also debate – which about is very the controversial,philosophical consciouscontroversially, wills initiateto suggest the movementthat our subjective is illusory. impression Libet accepted that thisour as we have seen – there is also debate about the philosophical conscious wills initiate the movement is illusory. Libet accepted this interpretation.as we have seen – there is also debate about the philosophical interpretation,conscious wills but initiate maintained the movement that conscious is illusory. will Libet can accepted still play this a interpretation. interpretation, but maintained that conscious will can still play a interpretation.I have here used systematically the term ‘conscious genuineinterpretation, role in butthe vetoingmaintained of initiated that conscious acts. will can still play a I have here used systematically the term ‘conscious genuine role in the vetoing of initiated acts. will’ ratherI have than here‘free usedwill’ systematicallyto avoid the broaderthe term philo ‘conscioussophical genuine roleMany in theneuroscientists vetoing of initiated and most acts. philosophers contest the will’ rather than ‘free will’ to avoid the broader philosophical Many neuroscientists and most philosophers contest the associationswill’ rather thanof the ‘free latter will’ term. to Nevertheless,avoid the broader many philosupporterssophical of claims aboutMany the neuroscientists supposed inefficacy and most of philosophersconscious will, contest and thisthe associations of the latter term. Nevertheless,26 many supporters of claims about the supposed inefficacy of conscious will, and this theassociations Libet claim, of the including latter term. Libet Nevertheless, himself 26, havemany used supporters the term of paperclaims summarises about the supposedtheir arguments. inefficacy At theof neurophysiologicalconscious will, and level, this the Libet claim, including Libet himself , have used the term paper summarises their arguments. At the neurophysiological level, the‘free Libet will’. claim, This hasincluding aroused Libet further himself controversy, 26, have becauseused the many term itpaper has summarises not been theirshown arguments. convincingly At the that neurophysiological a neural ‘decision’ level, ‘free will’. This has aroused further controversy, because many it has not been shown convincingly that a neural ‘decision’ critics‘free will’. have Thisargued has that aroused Libet’s further experimental controversy, paradig becausem was many sufficientit has not to been cause shown the movementconvincingly occurs that beforea neural the ‘decision’ time of critics havehave argued argued that that Libet’s Libet’s experimental experimental paradig paradigmm was was sufficient to cause the movement occurs before the time of ______critics have argued that Libet’s experimental paradigm was awarenesssufficient ofto thecause decision the movementto move. Even occurs if this before could thebe shown,time ofit 21______awareness of the decision to move. Even if this could be shown, it 21______Matsuhashi & Hallett op. cit., (16). wouldawareness not undermineof the decision the conceptionsto move. Even of free if this will could that arebe shown,defended it 2122 Matsuhashi & Hallett op. cit., (16). would not undermine the conceptions of free will that are defended 22 MatsuhashiMele op. cit. &, (12).Hallett op. cit., (16). 23 Mele op. cit., (12). bywould most not philosophers. undermine the conceptions of free will that are defended 22 Herrmann, C.S., Pauen, M., Min, B.K., Busch, N.A. & Rieger, J.W. by most philosophers. 23 MeleHerrmann, op. cit. ,C.S., (12). Pauen, M., Min, B.K., Busch, N.A. & Rieger, J.W. by most philosophers. 23‘Analysis of a choice-reaction task yields a new interpretation of Libet's ‘AnalysisHerrmann, of aC.S., choice Pauen,-reaction M., taskMin, yields B.K., a Busch,new interpretation N.A. & Rieger, of Libet's J.W. ‘Analysisexperiments’, of a Intl choice J. Psychophysiol.-reaction task (2008) yields 67, a new151-157. interpretation of Libet's 24experiments’, Intl J. Psychophysiol. (2008) 67, 151-157. Trevena, J. & Miller, J. ‘Brain preparation before a voluntary action: Acknowledgments 24experiments’,Trevena, J. Intl& Miller,J. Psychophysiol. J. ‘Brain (2008)preparation 67, 151-157. before a voluntary action: Acknowledgments evidence24 against unconscious movement initiation’, Consciousness & AcknowledgmentsThe author is grateful to Martyn Frame and Stuart Judge for their evidenceTrevena, against J. & Miller,unconscious J. ‘Brain movement preparation initiation’, before a Consciousnessvoluntary action: & The author is grateful to Martyn Frame and Stuart Judge for their evidenceCognition (2010)against 19, unconscious 447-456. movement initiation’, Consciousness & Thehelpful author comments is grateful on an earlierto Martyn draft Frameof this paper.and Stuart Judge for their Cognition25 (2010) 19, 447-456. helpful______comments on an earlier draft of this__ paper. Cognition25 Schurger, (2010) A., 19,Sitt, 447-456. J.D. & Dehaene, S. ‘An accumulator model for helpful27______comments on an earlier draft of this__ paper. 25 Schurger, A., Sitt, J.D. & Dehaene, S. ‘An accumulator model for ______27 Libet et al. op. cit., (1). __ spontaneousSchurger, neuralA., Sitt, activity J.D. prior & Dehaene,to self-iniated S. movement’,‘An accumulator Proc. modelNatl. Acad for 28 Libet et al. op. cit., (1). spontaneous neural activity prior to self-iniated movement’, Proc. Natl. Acad 27 Haggard, P. ‘Human volition: towards a neuroscience of will’, Nature Reviews spontaneousSci. USA doi:10.1073/pnas.1210467109 neural activity prior to self- (2012).iniated movement’, Proc. Natl. Acad 28 Haggard,Libet et al. P. op. ‘Human cit., (1). volition: towards a neuroscience of will’, Nature Reviews Sci.26 USA doi:10.1073/pnas.1210467109 (2012). 28 Libet, B. Mind Time, Cambridge Mass / London, UK: Harvard University NeuroscienceHaggard, P. (2008)‘Human 9: volition:934-946. towards a neuroscience of will’, Nature Reviews Sci.26 Libet, USA B. doi:10.1073/pnas.1210467109 Mind Time, Cambridge Mass (2012). / London, UK: Harvard University Neuroscience (2008) 9: 934-946. Press26 (2004). Neuroscience (2008) 9: 934-946. PressLibet, (2004). B. Mind Time, Cambridge Mass / London, UK: Harvard University Press (2004). The Faraday Papers The Faraday Papers The Faraday Papers The Faraday Papers are published by the Faraday Institute for Science and Religion, St Edmund’s College, Cambridge, CB3 0BN, UK, a charitable organisation for The Faraday Papers are published by the Faraday Institute for Science and Religion, St Edmund’s College, Cambridge, CB3 0BN, UK, a charitable organisation for education and research (www.faraday-institute.org). The opinions expressed are those of authors and do not necessarily represent the views of the Institute. The educationThe Faraday and Papers research are (www.faradaypublished by the-institute.org). 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