Dr. Devorah Segal on My Brain Made Me Do It: Did Neuroscience Destroy Free Wil


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Presentation to our Tikvah Scholars Program on April 24, 2012.

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  • If a friend takes your hand and moves it, you feel movement but not intention or agency – don’t feel responsible for it. Missing the sensation of free will: “I willed this and am the author if this action”
  • Compatibilism: dominant biological, psychological, legal, medical view. i.e. long-term smoker who tries to quit but keeps failing is not free – bec addiction thwarts desire. Most of us not completely free
  • Rare ppl can subserviate physical needs to higher purposes , i.e. Gandhi’s hunger strikes, Thich Quang Duc in Siagon, June 11, 1963 to protest persecution of Buddhists in South Vietnam by Catholic government. Our own history replete with examples. “ For the rest of us, who struggle to avoid going for dessert, freedom is always a question of degree rather than an absolute good that we do or do not possess.”
  • Why do we care? Free will is bedrock of society’s notions of responsibility, praise, and blame. It is about the degree of control we exert over our lives. Free will is central tenet of our faith – can’t reward or punish without it. Old Yediah and bechirah question. Some solutions include G-d outside of time witnessing events; Rambam: G-d’s knowledge completely unlike our knowledge, we don’t understand it so can’t resolve the paradox
  • Brodmann map: Different parts of the brain control different functions. Give some examples. Frontal lobe is “executive function” – oversees planning, coordinating, control. Neurons synapose on other neurons and communicate by electric and chemical signals.
  • Libet measured ERPs 500 msec before time that subject reports; indicated that the brain “decided” to move before person consciously aware of it. msec gap between activation and action – brain can veto. VS Ramachandran: We don’t have free will, but do have “free won’t” Action -> intention + agency
  • put people in fMRI and asked them to press right or left button at random and remember which letter of a random projected stream was projected at the time of the decision. Found motor area active just before the act and BA 10 (prefrontal) active 7 sec before subjects decided. Based on where brain activity was located, the researchers could predict which finger would press the button 60% of time (10% > chance). Once motor cortex involved, 75% correct. (so can still veto and change!) Haynes: “How can I call a will ‘mine’ when I don’t even know when it occurred and what it has decided to do?”
  • Frontal lobe regions plan movements with each hemisphere affecting opposite side of body. Normally, right-handed ppl choose to move right hand 60% of time. When used transcranial magnetic stimulation (uses magnetic waves to stimulate or inhibit parts of brain temporarily) on right hemisphere, moved left hand 80% of time. And ALL believed they has freely chosen which hand to move!
  • Legal: brain scans already being used to try to exonerate criminals (i.e. John Hinckley, Jr. – Reagan shooter)
  • “ Ghost in the machine” = nonphysical mind or soul
  • Dr. Devorah Segal on My Brain Made Me Do It: Did Neuroscience Destroy Free Wil

    1. 1. My Brain Made Me Do it: DidNeuroscience Destroy Free Will? Devorah Segal, MD, PhD April 24, 2012
    2. 2. Three steps to behavior1. Intention (the plan)2. Agency (the will)3. Movement (the act)
    3. 3. What is free will? Descartes: You are free if, under identical circumstances, you could have acted otherwise. Compatibilism: You are free if you can follow your own desires and preferences. A set of capacities for imagining future courses of action, deliberating about one’s reason’s for choosing them, planning one’s actions in light of this deliberation and controlling actions in the face of competing desires
    4. 4. Why do we care?
    5. 5. A Quick Tour of Your Brain
    6. 6. “The brain determines the mind, and the brain is a physical entity, subject to all the rules of the physical world. The physical world is determined, so our brains must also be determined. If our brains are determined, and the brain is the necessary and sufficient organ that enables the mind, we are then left with these questions: Are the thoughts that arise from our mind also determined? Is the free will that we seem to experience just an illusion?” (Gazzaniga, 2004)
    7. 7. Libet’s 1983 experiment
    8. 8. Newer version: fMRI
    9. 9. Transmagnetic cranial stimulation
    10. 10. What are the implications?
    11. 11. Can these questions be resolved?
    12. 12. References Ammon K and Dandevia SC. Transcranial magnetic stimulation can influence the selection of motor programmes. J of Neurology, Neurosurgery and Psychiatry. 1990; 53: 705-707 Chivers T. Neuroscience, free will and determinism. The Telegraph. Oct 12, 2010 Gazzaniga MS. The Ethical Brain. 2005; Dana Press Haynes JD. Decoding and predicting intentions. Ann NY Acad Sci. 2011; 1224: 9-21 Koch C. How physics and neuroscience dictate your “free” will. Sci Am Mind. May 2012; 22-27 Libet B, Gleason CA, Wright EW, Pearl DK. Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain. 1983; 106: 623-642 Nahmias, E. Is neuroscience the death of free will? The NY Times. Nov 30, 2011. epub Neuroscience of free will. Wikipedia Rosen J. The brain on the stand. The NY Times. March 11, 2007. 49 Soon CS, Brass M, Heinze HJ, Haynes JD. Unconscious determinants of free decisions in the human brain. Nat Neurosci. 2008; 11: 543–545 Tancredi LR. The neuroscience of “free will”. Behav Sci Law. 2007; 25: 295-308
    13. 13. Matsubashi experiment