Free will Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ===Neuroscience and neurophilosophy=== {{Main|Neurophilosophy|Neuroscience of free will}} {{see also|Neurostimulation}} It has become possible to study the living [[Human brain|brain]], and researchers can now watch the brain's decision-making process at work. A seminal experiment in this field was conducted by [[Benjamin Libet]] in the 1980s, in which he asked each subject to choose a random moment to flick their wrist while he measured the associated activity in their brain; in particular, the build-up of electrical signal called the [[readiness potential]] (after German [[Bereitschaftspotential]], which was discovered by [[Hans Helmut Kornhuber|Kornhuber]] & [[Lüder Deecke|Deecke]] in 1965.<ref>[[Hans Helmut Kornhuber|Kornhuber]] & [[Lüder Deecke|Deecke]], 1965. Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale. Pflügers Arch 284: 1–17.</ref>). Although it was well known that the readiness potential reliably preceded the physical action, Libet asked whether it could be recorded before the conscious intention to move. To determine when subjects felt the intention to move, he asked them to watch the second hand of a clock. After making a movement, the volunteer reported the time on the clock when they first felt the conscious intention to move; this became known as Libet's W time.<ref name="LGW" /> Libet found that the ''unconscious'' brain activity of the readiness potential leading up to subjects' movements began approximately half a second before the subject was aware of a conscious intention to move.<ref name="LGW"/><ref>{{cite journal | doi = 10.1017/S0140525X00044903 | last1 = Libet | first1 = B. | s2cid = 6965339 | year = 1985 | title = Unconscious cerebral initiative and the role of conscious will in voluntary action | journal = Behavioral and Brain Sciences | volume = 8 | issue = 4| pages = 529–66 }}</ref> These studies of the timing between actions and the conscious decision bear upon the role of the brain in understanding free will. A subject's declaration of intention to move a finger appears ''after'' the brain has begun to implement the action, suggesting to some that unconsciously the brain has made the decision ''before'' the conscious mental act to do so. Some believe the implication is that free will was not involved in the decision and is an illusion. The first of these experiments reported the brain registered activity related to the move about 0.2 s before movement onset.<ref name=Libet> {{cite journal|title=Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential) |author=Benjamin Libet |display-authors=etal |journal=Brain |year=1983 |volume=106 |pages=623–42 |url=http://trans-techresearch.net/wp-content/uploads/2012/02/Brain-1983-LIBET.pdf |doi=10.1093/brain/106.3.623 |pmid=6640273 |issue=3 |url-status=dead |archive-url=https://web.archive.org/web/20130526054605/http://trans-techresearch.net/wp-content/uploads/2012/02/Brain-1983-LIBET.pdf |archive-date=2013-05-26 }}</ref> However, these authors also found that awareness of action was ''anticipatory'' to activity in the muscle underlying the movement; the entire process resulting in action involves more steps than just the ''onset'' of brain activity. The bearing of these results upon notions of free will appears complex.<ref name=Strother>{{cite journal|title=The conscious experience of action and intention |author1=Lars Strother |author2=Sukhvinder Singh Obhi |journal=Exp Brain Res |volume=198 |year=2009 |pages=535–39 |doi=10.1007/s00221-009-1946-7 |url=http://publish.uwo.ca/~lstroth/StrotherObhi_EBR_2009.pdf |issue=4 |pmid=19641911 |s2cid=43567513 |url-status=dead |archive-url=https://web.archive.org/web/20141217013640/http://publish.uwo.ca/~lstroth/StrotherObhi_EBR_2009.pdf |archive-date=2014-12-17 }}</ref><ref name= Rosenbaum>A brief discussion of possible interpretation of these results is found in {{cite book |title=Human Motor Control |page=86 |url=https://books.google.com/books?id=MsFmds_ACBwC&pg=PA86 |isbn=978-0-12-374226-1 |year=2009 |edition=2nd |publisher=Academic Press |author=David A. Rosenbaum}}</ref> Some argue that placing the question of free will in the context of motor control is too narrow. The objection is that the time scales involved in motor control are very short, and motor control involves a great deal of unconscious action, with much physical movement entirely unconscious. On that basis "...free will cannot be squeezed into time frames of 150–350 [[Millisecond|ms]]; free will is a longer term phenomenon" and free will is a higher level activity that "cannot be captured in a description of neural activity or of muscle activation..."<ref name=Gallagher>{{cite book |title=Does Consciousness Cause Behavior? |author= Gallagher, Shaun|chapter=Chapter 6: Where's the action? Epiphenomenalism and the problem of free will |editor=Susan Pockett |editor2=William P. Banks |editor3=Shaun Gallagher |chapter-url=https://books.google.com/books?id=G5CaTnNksgkC&pg=PA119 |pages=119–21 |isbn=978-0-262-51257-2 |publisher=MIT Press |year=2009}}</ref> The bearing of timing experiments upon free will is still under discussion. More studies have since been conducted, including some that try to: * support Libet's original findings * suggest that the cancelling or "veto" of an action may first arise subconsciously as well * explain the underlying brain structures involved * suggest models that explain the relationship between conscious intention and action Benjamin Libet's results are quoted<ref>{{Cite book |last=Wegner |first=D. |title=The Illusion of Conscious Will |publisher=MIT Press |year=2002 |location=Cambridge, MA |author-link=Daniel Wegner}}</ref> in favor of epiphenomenalism, but he believes subjects still have a "conscious veto", since the readiness potential does not invariably lead to an action. In ''[[Freedom Evolves]]'', [[Daniel Dennett]] argues that a no-free-will conclusion is based on dubious assumptions about the location of consciousness, as well as questioning the accuracy and interpretation of Libet's results. Kornhuber and Deecke underlined that absence of conscious will during the early Bereitschaftspotential (termed BP1) is not a proof of the non-existence of free will, as also unconscious agendas may be free and non-deterministic. According to their suggestion, man has relative freedom, i.e. freedom in degrees, that can be increased or decreased through deliberate choices that involve both conscious and unconscious (panencephalic) processes.<ref>[[Hans Helmut Kornhuber|Kornhuber]] & [[Lüder Deecke|Deecke]], 2012. ''The will and its brain – an appraisal of reasoned free will''. University Press of America, Lanham, MD, {{ISBN|978-0-7618-5862-1}}.</ref> Others have argued that data such as the Bereitschaftspotential undermine epiphenomenalism for the same reason, that such experiments rely on a subject reporting the point in time at which a conscious experience occurs, thus relying on the subject to be able to consciously perform an action. That ability would seem to be at odds with early epiphenomenalism, which according to Huxley is the broad claim that consciousness is "completely without any power... as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery".<ref name="Flanagan1992">{{cite book |first=O.J. |last=Flanagan |year=1992 |title=Consciousness Reconsidered |series=Bradford Books |publisher=MIT Press |isbn=978-0-262-56077-1 |lccn=lc92010057 |url=https://books.google.com/books?id=yFOqQgAACAAJ |page=131}}</ref> Adrian G. Guggisberg and Annaïs Mottaz have also challenged those findings.<ref>{{cite journal|pmc=3746176 | pmid=23966921 | doi=10.3389/fnhum.2013.00385 | volume=7 | title=Timing and awareness of movement decisions: does consciousness really come too late? | year=2013 | journal=Front Hum Neurosci | pages=385 | last1 = Guggisberg | first1 = AG | last2 = Mottaz | first2 = A| doi-access=free }}</ref> A study by Aaron Schurger and colleagues published in the Proceedings of the National Academy of Sciences<ref>{{cite journal|title=An accumulator model for spontaneous neural activity prior to self-initiated movement |first1=Aaron|last1=Schurger |first2=Jacobo D.|last2=Sitt|first3=Stanislas|last3=Dehaene|date=16 October 2012 |journal=PNAS|volume=109|issue=42|pages=16776–77 |doi=10.1073/pnas.1210467109|pmid=22869750|pmc=3479453|bibcode=2012PNAS..109E2904S|doi-access=free}}</ref> challenged assumptions about the causal nature of the readiness potential itself (and the "pre-movement buildup" of neural activity in general), casting doubt on conclusions drawn from studies such as Libet's<ref name="LGW">{{cite journal |doi=10.1093/brain/106.3.623 |title=Time of Conscious Intention to Act in Relation to Onset of Cerebral Activity (Readiness-Potential) |year=1983 |last1=Libet |first1=Benjamin |last2=Gleason |first2=Curtis A. |last3=Wright |first3=Elwood W. |last4=Pearl |first4=Dennis K. |journal=Brain |volume=106 |issue=3 |pages=623–42 |pmid=6640273}}</ref> and Fried's.<ref name=Fried>{{cite journal |doi=10.1016/j.neuron.2010.11.045 |title=Internally Generated Preactivation of Single Neurons in Human Medial Frontal Cortex Predicts Volition |year=2011 |last1=Fried |first1=Itzhak |last2=Mukamel |first2=Roy |last3=Kreiman |first3=Gabriel |journal=Neuron |volume=69 |issue=3 |pages=548–62 |pmid=21315264 |pmc=3052770}}</ref> A study that compared deliberate and arbitrary decisions, found that the early signs of decision are absent for the deliberate ones.<ref>{{Cite journal|last1=Maoz|first1=Uri|last2=Yaffe|first2=Gideon|last3=Koch|first3=Christof|last4=Mudrik|first4=Liad|date=2019-02-28|title=Neural precursors of decisions that matter—an ERP study of deliberate and arbitrary choice|journal=eLife|volume=8|doi=10.7554/elife.39787|pmid=31642807|pmc=6809608 |doi-access=free }}</ref> It has been shown that in several brain-related conditions, individuals cannot entirely control their own actions, though the existence of such conditions does not directly refute the existence of free will. Neuroscientific studies are valuable tools in developing models of how humans experience free will. For example, people with [[Tourette syndrome]] and related [[tic disorder]]s make involuntary movements and utterances (called [[tic]]s) despite the fact that they would prefer not to do so when it is socially inappropriate. Tics are described as semi-voluntary or ''unvoluntary'',<ref name=TSADef>Tourette Syndrome Association. [https://web.archive.org/web/20050322170245/http://www.tsa-usa.org/research/definitions.html Definitions and Classification of Tic Disorders.]. Retrieved 19 August 2006.</ref> because they are not strictly ''involuntary'': they may be experienced as a ''voluntary'' response to an unwanted, premonitory urge. Tics are experienced as irresistible and must eventually be expressed.<ref name=TSADef/> People with Tourette syndrome are sometimes able to suppress their tics for limited periods, but doing so often results in an explosion of tics afterward. The control exerted (from seconds to hours at a time) may merely postpone and exacerbate the ultimate expression of the tic.<ref name=Zinner>{{cite journal | last1 = Zinner | first1 = S.H. | year = 2000 | title = Tourette disorder | journal = Pediatrics in Review| volume = 21 | issue = 11| pmid = 11077021 | pages = 372–83 | doi=10.1542/pir.21-11-372| s2cid = 7774922 }}</ref> In [[alien hand syndrome]], the affected individual's limb will produce unintentional movements without the will of the person. The affected limb effectively demonstrates 'a will of its own.' The [[sense of agency]] does not emerge in conjunction with the overt appearance of the purposeful act even though the sense of ownership in relationship to the body part is maintained. This phenomenon corresponds with an impairment in the premotor mechanism manifested temporally by the appearance of the readiness potential recordable on the scalp several hundred milliseconds before the overt appearance of a spontaneous willed movement. Using [[functional magnetic resonance imaging]] with specialized multivariate analyses to study the temporal dimension in the activation of the cortical network associated with voluntary movement in human subjects, an anterior-to-posterior sequential activation process beginning in the supplementary motor area on the medial surface of the frontal lobe and progressing to the primary motor cortex and then to parietal cortex has been observed.<ref name=Kayser>{{cite journal | doi = 10.1002/hbm.20771 | last1 = Kayser | first1 = A.S. | last2 = Sun | first2 = F.T. | last3 = D'Esposito | first3 = M. | year = 2009 | title = A comparison of Granger causality and coherency in fMRI-based analysis of the motor system | journal = Human Brain Mapping | volume = 30 | issue = 11| pages = 3475–94 | pmid = 19387980 | pmc = 2767459 }}</ref> The sense of agency thus appears to normally emerge in conjunction with this orderly sequential network activation incorporating premotor association cortices together with primary motor cortex. In particular, the supplementary motor complex on the medial surface of the frontal lobe appears to activate prior to primary motor cortex presumably in associated with a preparatory pre-movement process. In a recent study using functional magnetic resonance imaging, alien movements were characterized by a relatively isolated activation of the primary motor cortex contralateral to the alien hand, while voluntary movements of the same body part included the natural activation of motor association cortex associated with the premotor process.<ref name=Assal>{{cite journal | doi = 10.1002/ana.21173 | last1 = Assal | first1 = F. | last2 = Schwartz | first2 = S. | last3 = Vuilleumier | first3 = P. | s2cid = 14180577 | year = 2007 | title = Moving with or without will: Functional neural correlates of alien hand syndrome | journal = Annals of Neurology | volume = 62 | issue = 3| pages = 301–06 | pmid = 17638304 }}</ref> The clinical definition requires "feeling that one limb is foreign or has a ''will of its own,'' together with observable involuntary motor activity" (emphasis in original).<ref name=Doody>{{cite journal | doi = 10.1136/jnnp.55.9.806 | last1 = Doody | first1 = RS | last2 = Jankovic | first2 = J. | year = 1992 | title = The alien hand and related signs | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 55 | issue = 9| pages = 806–10 | pmid = 1402972 | pmc = 1015106 }}</ref> This syndrome is often a result of damage to the [[corpus callosum]], either when it is severed to treat intractable [[epilepsy]] or due to a [[stroke]]. The standard neurological explanation is that the felt will reported by the speaking left hemisphere does not correspond with the actions performed by the non-speaking right hemisphere, thus suggesting that the two hemispheres may have independent senses of will.<ref name=Scepkowski>{{cite journal | doi = 10.1177/1534582303260119 | last1 = Scepkowski | first1 = L.A. | last2 = Cronin-Golomb | first2 = A. | year = 2003 | title = The alien hand: cases, categorizations, and anatomical correlates | journal = Behavioral and Cognitive Neuroscience Reviews | volume = 2 | issue = 4| pages = 261–77 | pmid = 15006289 }}</ref><ref name=Bundick>{{cite journal | doi = 10.1136/jnnp.68.1.83 | last1 = Bundick | first1 = T. | last2 = Spinella | first2 = M. | year = 2000 | title = Subjective experience, involuntary movement, and posterior alien hand syndrome | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 68 | issue = 1| pages = 83–85 | pmid = 10601408 | pmc = 1760620 }}</ref> In addition, one of the most important ("first rank") diagnostic symptoms of [[schizophrenia]] is the patient's delusion of being controlled by an external force.<ref name="Schneider">{{Cite book |last=Schneider |first=K. |title=Clinical Psychopathology |publisher=Grune and Stratton |year=1959 |location=New York}}</ref> People with schizophrenia will sometimes report that, although they are acting in the world, they do not recall initiating the particular actions they performed. This is sometimes likened to being a robot controlled by someone else. Although the neural mechanisms of schizophrenia are not yet clear, one influential hypothesis is that there is a breakdown in brain systems that compare motor commands with the feedback received from the body (known as [[proprioception]]), leading to attendant [[hallucination]]s and delusions of control.<ref name=frith>{{cite journal | doi = 10.1016/S0165-0173(99)00052-1 | last1 = Frith | first1 = CD | last2 = Blakemore | first2 = S | last3 = Wolpert | first3 = DM | title = Explaining the symptoms of schizophrenia: abnormalities in the awareness of action | journal = Brain Research. Brain Research Reviews | volume = 31 | issue = 2–3 | pages = 357–63 | year = 2000 | pmid = 10719163 | s2cid = 206021496 }}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. 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