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Blackmore Chapter 9 - “We know what it is to get out of...

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Unformatted text preview: “We know what it is to get out of bed on a freezing morning in a room without a fire, and how the very Vital principle within us protests against the ordeal,” said William James, describing the agonizing, the self—recriminarion and the lure of comfort against the cold. “Now how do we ever get up under such cir— cumstances?” he asked. “If I may generalize from my own experience, we more often than not get up without any struggle or decision at all. We suddenly find that we have got up” (James, 1890, Vol. 2: 524). When the inhibitory thoughts briefly cease, he said, the idea of getting up produces its appropriate motor effects, by “ideo—motor action,” and we are up. What, then, is the role of free will? The problem of free will is reputed to be the most discussed philosophical problem of all time. Since the Greek philosophers 2000 years ago, the main problem has seemed to lie with determinism. If this universe runs by deter— ministic laws, then everything that happens must be inevitable, so the argu— ment goes, and if everything is inevitable, there is no room for free will, no point in my “doing” anything, no sense in which I “could have done other- wise”——with obvious implications for morality and the law. Among modern philosophers, non—compatibilists argue that if the universe is deterministic, then free will must be an illusion, while compatibilists find many and varied ways in which determinism can be true and yet free will remain. IRACTICE I DOING THIS?- When you find yourself asking ”Am I conscious now?” observe what you are doing and ask yourself, ”Am [doing this?” You might be walking, drinking a cup of coffee or picking up the phone to ring a friend. Whatever it is, ask yourself what caused the action. Did you consciously think about it first? Did your own conscious thoughts cause it to happen? Did it just happen by itself? You might like to take a short time—say lO minutes—and try to observe the origins of all your actions during that time. In each case ask, ”Did I do that?” \ / There are many arguments here, and little agreement, except perhaps for a widespread rejection of free will as a magical or God—like force that comes out of nowhere. If free will is not illusory, it is certainly not magic. The question is, what other possibilities are there? If we add chance or randomness, as modern physics does, we get back to the Greek philosopher Democritus, who said that “everything in the universe is the fruit of chance and necessity.” And it is not chance or randomness that we seek, but some way in which our own efforts really make a difference. This is where the connection with self comes in, for we feel as though “I” am the one who acts, “I” am the one who has free will. “I” decided to spring out of bed this morning, and did so. When the chosen action then happens, it seems as though my conscious thought was responsible. Indeed it seems that without the conscious thought I would not have done what I did, and that I consciously caused the action by deciding to do it. The question is, does con— sciousness really play a role in decision making and choice? Is this sense of conscious agency real or an illusion? As ever, William James got to the heart of the matter when he said . . . the whole feeling of reality, the whole sting and excitement of our voluntary life, depends on our sense that in it things are really being decided from one moment to another, and that it is not the dull rattling off of a chain that was forged innumerable ages ago. This appearance, which makes life and history tingle with such a tragic zest, may not be an illusion. (James, 1890, i: 453) As we have seen (Chapters 2 and 3), James rejected the idea of a persisting self but still believed in a spiritual force. The sense of effort in both attention and volition is, in his view, not an illusion but the genuinely causal force of con- scious, personal will. CONSCIOUSNESS As with all talk of illusions, remember that an illusion is not something that does not exist, but something that is not what it seems. So, Once again, it is important to be clear about the way it seems for you. Does it seem as though you have conscious free will? If so, then ask yourself whether this could be an illusion, and if it is an illusion, how you can possibly live with that idea (Chapter 27). If it does not seem to you that you have conscious free will, then you may read all this with an air of amused detachment. Note that we are concerned here with consciousness. The question is not is for it. ” whether human beings are agents. We may safely assume that they are. Humans are living biological creatures that survive, like all other creatures, by having boundaries between themselves and the outside world and by taking control over certain aspects of their environment. They respond to events, make plans and act accordingly, at least when they are not restrained or coerced. We humans are very complicated agents with intricate plans and many available options. Neither need we doubt that thought, deliberation and emotions play a part in decisions. Weighing possible actions and comparing their likely out— comes is the sort of thing that intelligent animals are good at, from a cat deciding when to pounce, to a chimpanzee weighing the likely consequences of challenging a dominant ally. \Y/e can look to see which parts of the brain are active in such deci- sion making and, in principle at least, trace how their activation results in motor activity. The tricky question concerns where conscious— ness comes into all of this. THE ANATOMY OF VOLITION When we carry out any voluntary act, many areas of the brain, especially the frontal lobes, are involved (Spence and Frith, 1999). In outline, pre— frontal regions are thought to initiate motor acts. These send connections to premotor regions, \ ACTIVITY: Getting out of bed on a cold morning Try William lames’s famous meditation (as he called it) and watch what happens when you get out of bed on a cold morning. If you don’t live somewhere cold enough, iust choose a morning when you really don’t want to get up. Alternatively try getting out of a both when the water is going cold and you've been in there too long. Watch what happens. What thoughts go through your mind as you struggle to get out? What emo- tions do you feel? Do you speak to yourself or try to persuade yourself? If so, who or what is strug- gling against whom or what? What happens in the end? You might like to write a short description, as James did (see James, l890, ii: 524—5). What does this tell you about free will? which program the actions, and they in turn project to the primary motor cor- tices and hence to motor output. Broca’s area produces the motor output for speech and, in most right—handed people, is in the left inferior frontal gyrus. Medially, near the midline, are the supplementary motor area, which is involved in the sequencing and programming of motor acts to fit a “motor ) plan,’ and the anterior cingulate, which is a complex area involved in atten- tion to, and selection of, the information needed for action, as well as emotion and pain. ,thAgency and free will “All theory is against the freedom of the will; all experience Samuel Johnson, l79l {HAPTER NINE Lateral view of the left hemisphere Frontal lobe Premotor Prefrontal Primary motor Parietal lobe Oocipital Broca’s lobe area Temporal lobe Orbito-frontal Medial view of the right hemisphere Supplementary motor area Anterior cingulate cortex Ventral prefrontal Some of this is known from the effects of brain damage. For example, there is the famous case of railroad worker Phineas Gage. In 1848 a tamping iron was blown straight through his frontal cortex, leaving him a changed personality and no longer able to behave responsibly (Damasio, 1994). Damage to dorso— lateral prefrontal cortex can lead to a lack of spontaneous activity and to repetitive, stereotypic actions. Lesions of the prefrontal region and corpus callosum can produce the extraordi— nary complaint of “alien hand,” in which patients say that their hand is out of their control and has a will of its own. Damage to only the corpus callosum can produce “anarchic hand” syndrome in which the patient’s two hands struggle to produce opposite effects—for example, one trying to undo a button while the other tries to do it up. Experiments with single cell record— ing in monkeys also provide informa— tion about the neuronal mechanisms of voluntary control of behavior (Schultz, 1999), and new methods of brain imaging have recently allowed FIGURE 9.1 0 Schematic view of the human brain showing the tour lobes and the molar subdivisions of the , . frontal cortex, The numbers refer to the regions delineated by Korbinian Brodmann on the basis detailed SWdY ”1 humans. For at a detailed study of neural architecture. Only a subset of these regions are shown. The dorsolateral prefrontal cortex consists of the regions labeled 9 and 46 (after Spence and Frith, i999), example, Frith er al. (1991) used PET (positron emission tomography; see Chapter 16) to investigate the func— tional anatomy of volition. In one condition subjects repeated words read by the experimenter at the rate of one every three seconds. In the other condition they heard only one letter and had to say a word of their choice beginning with that letter. Subtracting the activations seen in one condition from those in the other revealed a difference in the left dorsolateral prefrontal cortex (DLPFC) and anterior cingulate. Other similar studies showed an increase in activity in DLPFC when actions were being selected and initiated. From a review of such studies Spence and Frith (1999) conclude that even the simplest motor procedures require complex and distributed neuronal activity, but the DLPFC seems to be uniquely associated with the subjective experience of deciding when and how to act. CONSCIOUSNESS The problem for our purposes here is that it fw— doesn’t feel like neurons firing, whether in the f A CT I V l TY O DLPFC or anywhere else. It feels as though there libet’ s voluntary act is something else—my consciousness—that makes ,2 i me free to act the way I want. In Chapter 3 we g i dealt with theories that do, and do not, give a E libet’s experiment is complex, and the arguments ‘ causal role to consciousness. Here we will con— about its interpretation are fierce. ltwill help you E sider how this relates to the sense of personal E understand it if you have practiced the role ofone l- conscious agency. of his subiects. Students who have done this are . much more likely to think up, for themselves, all the E i classic obiectiors to libet’s conclusion. y So, as a class demonstration, ask everyone to hold act their right am in front of them and then, when- ever they feel like it, consciously, deliberately and of their own free will, flex their fingers or wrist. 'l hey lould keep doing this for some time — ideally until hey have done it 40 times (as in libet’s experi- rent) — but sirce people vary in how frequently fey do the action (and some may freely choose not ‘. do it at all), about two minutes is usually enorgh. ow ask your SJbiects whether the action really seenied free or not. What was going through the‘r ""irds when they’ ’decided to act.” Could they have dore otherwise? ls ths a good model fora ”span- ‘oneous voluntary cct”? ow you need to the ”,W’ the time at which t ey dec'ded to act. Stand 'n front of the group, hold you arm straight OJl and use your own hand to 'epresent the rotating light spot (if you have a hoe aud once, held a brg tobiect in your hand to make 't ore visible). Make sure your arm rotates clock- wise from the viewers’ point of view and steadily at roughly one revolut'or every two seconds (Libet’s spo went a little slower, but one in two works well; practice first). Now as the audience to do the sane flexing task cs before, but this time they must, after they have acted, shout out the clock pos'tion at the momert when they decided to act. You now have a room full of people shouting out different times all "t once. The question is, could they easily do this? Most people find they can. Libet measured three things: the start of the action itself, the start of brain activity leading to the action and the decision to act. Ask yourself which you expect to come first, or get everyone to put up their hands. THE ROLE OF CONSCIOUS WILL lN VOLUNTARY ACTION Hold out your hand in front of you. Now, when- ever you feel like it, consciously, deliberately, and of your own free will, flex your wrist. Keep doing this for some time—until your arm gets too tired. just flex your wrist whenever you want, and try to observe what goes through your mind as you do so. If you don’t want to do it at all that’s fine—that is your conscious deci— sion. If you want to do it frequently, that is fine too. Now ask yourself What started the move— ment, or prevented it, each time. \X/hat caused your action? —+m This simple task formed the basis of one of the best—known experiments in the history of con— sciousness studies: Libet’s study of “Unconscious cerebral initiative and the role of conscious will in voluntary action" (1985). Since the 19605 it had been known that voluntary motor actions are preceded by a “readiness potential” (RP): a slow negative shift in electrical potential that can be recorded from electrodes on the scalp up to a second or more before the action takes place. This long time interval (on average 8001115) prompted Libet to wonder “whether the con- scious awareness of the voluntary urge to act likewise appears so far in advance” (ibid: 529). .. He reasoned that if a conscious intention or deci— sion initiates the action, then the subjective ex— perience of intending should come first, or at the latest together with the start of the cerebral processes. This was what his experiment investi- gated. He needed to time three events: the start of YOU are ”OW lead)’ l0 dlSCUSS l-lbells eXpellmenl 0nd the action itself, the start of the RP, and the Whfll his results leUlll’ mean. moment of the conscious decision to act. Timing the action itself was easily done with electrodes on the appro— priate muscle. Timing the RP was also relatively straightforward. The change in potential that marks the beginning of the RP can only be clearly seen when averaged over many repetitions, so Libet had his subjects carry out the flexion 40 times in each series of trials. Using the time of the action as a reference, these 40 trials could then be mathe-I Movemen‘i' HGURE 9.2 . in his experiments on voluntary action lihet (1985) timed three things: M, the movement of the ma tically averaged even though the hand or wrist: RP, the readiness potential detected from motor cortex using EEG; and W or ”will.” W was timed by asking the subject to watch a revolving spot and soy (afterward) where the spot was when he decided to move. subject freely chose when to move {Libet et al., 1983). The source of this RP was thought to be the sup— plementary motor area. The real problem is how to measure the moment when the subject becomes conscious of the urge, or will, to move—Libet called this moment “W” for “will.” If you ask subjects to say “Now” when they feel like moving, the action of speaking may not only interfere with the wrist movement but may also involve its own RP and another delay. 50 Libet used the following method. A spot of light revolved once every 2.56 seconds, in a clock circle on a screen. Subjects were asked to watch the spot carefully and then, after they had flexed their wrist, to report where the spot was at the moment they felt the urge to move. 50 on each trial they would flex their wrist and then say “15” or “35,” meaning that this was the position of the Spot at the moment they decided to act. A control series, in which subjects reported the time of a skin stimulus by using the clock method, showed that their estimates were generally accurate and slightly in advance of the actual stimulus. In another control, subjects were asked to time their awareness of actually moving (M). They had no trouble following these instructions nor in discriminating M from W, W being, on average, 120 ms before M. Using these controls, Libet was convinced that the timing of W was sufficiently accurate. He could now answer his question: which comes first, the readiness potential or the conscious decision to act? The answer was clear. The RP came first. On average the RP started 550 ms (:150 ms) before the action and W only 200 ms before. In some trials the sub— jects said they had been thinking about the action some time in advance, or preplanning it. On these trials the RP began over a second before the action, but for series in which all 40 acts were reported as fully spontaneous and unplanned, the RP began 535 ms before the action, and W just 190 ms before the action. Further analysis showed that this held for different ways of meas- uring both RP and W. In conclusion, the conscious decision to act occurred approximately 350 ms after the RP. CONSCIOUSNESS What should we make of this finding? With Self-initiated act: sequence Libet we may wonder, “If the brain can initiate a voluntary act before the appearance ofconscious intention . . . is there any role for the conscious function?” (Libet, 1985: 536). That is the crux. +-> These results seem to show (as did Libet’s previ— ous work; see Chapter 3) that consciousness comes too late to be the cause of the action. For those who accept the validity of the method, there are two main ways ofresponding to Libet’s results. The first is to say, “Well, that’s obvious! If consciousness came first, it would be magic.” Presumably this ought to be the stan- dard reaction of anyone who denies dualism. RPI RP ll (Pre-plans) (No pre-plans) (Conscious wish) EMG -1000 —500 —ZOO 0 msec Indeed, the result should have been completely <———> unsurprising. Instead, even though most psy— chologists and philosophers deny believing in 350 ms FIGURE 9.3 - According to Libet the sequence at events in a self-initiated voluntary act is as shown. Preplanning (RPl) occurs as much as a second before the movement, For magic, these r 351113 caused a great stir. NOt only spontaneous actions without pteplanning, activity (RPII) begins about half a second was there a wide—ranging debate in Behavioral before the movement. Subiective awareness of the will to move appears about and Brain Sciences, but the experiment was still frequently cited, and hotly argued over, nearly 20 years after it was carried out (Libet, 1999). The second response is to seek some remaining causal role for consciousness in voluntary action. Libet took this route and argued as follows. It is possible to believe, he said, that conscious intervention does not exist and the subjec— tive experience of conscious control is an illusion, but such a belief is “less attractive than a theory that accepts or accommodates the phenomenal fact” (Libet, 1999: 56) and is not required even by monist materialists. For example, Sperry’s emergent consciousness (see Chapter 7) is a monist theory in which consciousness has real effects. Alternatively the results are compati— ble with dualist interactionism (Popper and Eccles, 1977). Libet therefore pro- posed “that conscious control can be exerted before the final motor outflow to select or control volitional outcome. The volitional process, initiated unconsciously, can either be consciously permitted to proceed to consumma- tion in the motor act or be consciously ‘vetoed’” (Libet, 1985: 536—7). The idea, then, is that unconscious brain events start the process of a voluntary act, but then just before it is actually carried out, consciousness may say either “Yes” or “No”; the action either goes ahead or not. This would happen in the last 150 to 200 ms before the action. Libet provides two kinds of evidence for this conscious veto. First, subjects sometimes reported that they had...
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