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Freewill 3Freewill: 3: Further articles relative to freewill 1.) Conscious attention & brain activity - Haggard & Libet 2.) Timing volition - Zhu 3.) The Neuroscience of Movement - Susan Pockett 4.) Free Choice & the Human Brain - Richard Passingham & Hakwan Lau 5.) Where’s the action? Epiphenomenalism and the problem of freewill - Shaun Gallagher 6.) Empirical constraints on the problem of freewill - Peter Ross 7.) Towards a dynamic theory of intentions - Elizabeth Pacherie 8.) Phemenology & the feeling of doing: Wegner on the conscious will - Tim Bayne Conscious Intention & Brain Activity Peter Haggard, Institute of Cognitive Neuroscience, University College London & Benjamin Libet Journal of Consciousness Studies, 8, No. 11, 2001, pp. 47-63 Haggard advances the idea that conscious awareness of intention is linked to the choice of a specific action, rather than the initiation of an action process. Libet’s experiments had suggested that readiness potentials for action happened before the consciousness of volition to act. The experiments appeared to confirm a pre-existing neuroscientific bias in favour of the idea that consciousness had little or no role to play. His theory seemed to show that unconscious preparations for action preceded awareness of the wish to act. He did however try to save freewill by positing a conscious veto that could prevent the action being performed. This qualification of his initial finding proved a good deal less popular with the neuroscientific establsihment. Haggard’s first substantial criticism of the Libet experiment is that the fact that the readiness potential came before the conscious awareness is necessary but not sufficient to establish a causal relationship. Other neural events might also impact consciousness. Haggard distinguishes between the initial readiness potential and the lateral readiness potential (LRP), which comes when the subject has decided which hand to use in the Libet experiment. The LRP was found to have a closer correlation with perceived moment of conscious volition than the original readiness potential (RP) highlighted by the Libet experiment. This suggested that the conscious intention was related to specific rather than a general preparation for action. Haggard asks why it is might be that consciousness was associated with the selection of a specific action. Computational work relative to motor control has established that movement selection is the most difficult problem in action, because there are an infinite number of possible movements that could achieve a particular end, and there is no unique solution. Haggard suggests a relation between the necessary information processing for movement selection and conscious information processing. He suggests that his proposition could be tested by experiment, by matching experience of intention to movement selecting processing in the brain. In terms of the Libet veto, Haggard connects this to the decision as to whether a specific action selected at the point of the readiness potential is in fact the best possible action, or a suitable action at all. References:- Eimer, M. (1998) The laterilised readiness potential Behaviour Research Methods, Instruments and computers, 30, pp. 146-56 Fried, I. et al (1991) SMA studied by electrical stimulation Journal of Neuroscience, 11, pp. 3656-66 Haggard, P. & Eimer, M. (1999) Brain potentials and conscious awareness Experimental Brain Research, 126, pp. 128-33 Haggard, P. & Johnson, H. (2001) Attention and awareness in Ed. Weiss, P. Action and Visuo-spatial Attention Haggard, P. & Magno, E. (1999) Awareness of action with TMS Experimental Brain Research, 127, pp. 102-7 Haggard, P. et al Action, binding and awarenes in Ed. Prinz, W. & Hommel, B. Common Mechanisms in Perception and Action Oxford University Press Libet, B. (1985) Conscious will in voluntary action Behavioural and Brain Sciences, 8, pp. 529-66 Libet, B. (1999) Do we have free will? Journal of Consciousness Studies, 6, (8-9), pp. 47-57 Libet, B. et al (1983) Time of conscious intention to act Brain, 102, pp. 623-42 Libet, B. et al (1982) Readiness potentials preceding voluntary acts Electroencephalogy and Clinical Neurophysiology, 54, pp. 322-5 Jing Zhu Reclaiming Volition: An alternative interpretation of Libet’s experiment Journal of Consciousness Studies, 10, No. 11, 2003, pp. 61-77 The author suggests that there may be another way of looking at the famous Libet experiment that has been taken by many to disprove the existence of goodwill. The main thrust of his argument is that more account should be taken of the conscious intentions formed by subjects at the beginning of the experiment. He also wants to make a distinction between a conscious intention to act, and what he sees as a mere urge to move. Zhu refers to Searle’s argument that there are gaps in the processes of reasoning and subsequent action. There is firstly a gap between the various reasons, and actually making up your mind. The reasons for making the decision are not causally sufficient. Secondly, having made up your mind on a course of action this is also not causally sufficient for actually making the action. Thirdly, having started on the action, this is not causally sufficient for its completions and further effort has to continue. Searle argues that these gaps are filled by volition. Searle distinguishes between acts of will, by which an agent initiates an action, and states of mind that persist over time, guide actions and monitor outcomes. Searle admits that many routine actions are carried out without any prior conscious intention, and that even when there is prior intention for a large scale task, this may require intermediate steps for which there is no prior plan. Zhu is unusual in seriously questioning the result of Libet’s volition experiment as opposed to merely arguing over its interpretation. Zhu queries the extent to which the small flexion performed by Libet’s subjects were as free and spontaneous as a normal action performed outside the laboratory, since they were specifically requested by the experimenter, and there was therefore a prior intention to make the relevant flexions. The only decision involved the timing of the action. The decision to perform the action as such is preplanned and will be performed within some relatively short time scale. It is therefore at least reasonable to question Libet’s central conclusion that all apparently voluntary acts were initiated at the unconscious level. Zhu argues that given the prior intention it is questionable to ascribe every thing to do with the subsequent movement to the unconscious. The subjects were actually instructed to let the urge to act appear on its own, something which might more plausible appear downstream of an unconscious initiation than might have a formed intention. Zhu mentions an experiment by Keller & Heckhausen (1990) in which a replication of the Libet experiment was compared to a situation in which similar small body movements were unconscious. The readiness potentials were at almost the same time before the actions for both unconscious and conscious movements, but the RPs before unconscious movements had much smaller amplitudes than those before conscious actions. The scalp distribution of the RPs was also different suggesting that different neural structures could be involved in conscious and unconscious movements, the supplementary motor cortex in the case of conscious movements and the lateral motor cortex in the case of unconscious movements. Zhu supports Keller and Heckhausen in a possibly more doubtful claim that because of introspection in respect of the urge to act in the Libet experiment, normally unconscious acts have been brought into consciousness. It has been found that RP’s have greater amplitude and length according to the amount of effort and attention involved in a task. Libet himself found that subjects who preplanned their flexions had longer RPs with a larger amplitude. The earlier experiments by Kornhuber and Deecke had found that RPs preceding voluntary action were at maximum amplitude close to the SMA. Other studies closely associate the SMA with voluntary actions. The SMA is active before the primary motor cortex during voluntary acts suggesting it has some part in their direction. In Penfields studies it was found that a stimulus to the primary motor cortex produced bodily movements that the subject perceived as involuntary. By contrast later studies (Fried et al, 1991) showed that stimulation of the SMA produced an urge to act. References:- Cunnington, R. et al (1996) The role of the SMA in voluntary movement Human Movement Science, 15, pp. 627-47 Deecke, L. (1987) Movement preparation in SMA and motor cortex in Ed. Porter, R. Motor Areas of the Cerebral Cortex Wiley Deecke, L., Grozinger, B. & Kornhuber, H. (1976) Biological Cybernetics, 23, pp. 99-119 Deecke, L. et al (1997) New evidence for SMA activation prior to voluntary movement Proceedings of the 14th International Congress of EEG and Clinical Neurophysiology Eccles, J. (1982) Initiation of voluntary movements by the SMA Archives Pschiat. Nervenkr, 231, pp. 423-41 Fried, L. et al (1991) Organisation of SMA studied by electrical stimulation Journal of Neuroscience, 11, pp. 3656-66 Goldberg, G. (1987) SMA structure and function in Ed. Pececman, E. Behavioural and Brain Science, 8, pp. 567-616 Goldberg, G. (1987) Function of the pre-motor systems of the frontal lobe Ed. Pececman, E. The Frontal Lobe Revisited IRBN Press Haggard, P. & Libet, B. (2001) Conscious intention and brain activity Journal of Consciousness Studies, 8 (11), pp. 47-63 Heckhausen, H. (1991) Motivation and Action Springer Verlag Keller, I. & Heckhausen, H (1990) Readiness potentials preceding motor acts Electroencephalogy and Clinical Neurophysiology, 76, pp. 351-61 Kornhuber, H. (1984) Stages of voluntary decision Experimental Brain Research, 9, (suppl.) pp. 42-9 Kornhuber, H. & Deecke, L. (1985) Starting function of the SMA Behavioural and Brain Sciences, 8, pp. 591-2 Kornhuber, H. et al (1989) Will, volition, attention and cerebral potentials in Ed. Hershberger, W. Volitional Action Elsevier Libet, B. (1985) Unconscious cerebral initiative and conscious will Behavioural and Brain Science, 8, pp. 529-66 Libet, B. (1999) Do we have freewill? Journal of Consciousness Studies, 6, (8-9), pp. 47-57 Libet, B. et al (1982) RPs preceding spontaneous and preplanned acts Electroencephalography and Clinical Neurophysiology, 54, pp. 322-35 Libet, B. et al (1983a) Time of conscious intention to act Brain, 106, pp. 623-42 Libet, B. et al (1983b) Pre-event potential recorded at the vertex Electroencephalography and Clinical Neurophysiology, 56, pp. 367-72 Naatanen, R. (1985) Brain physiology and unconscious movements Behavioural and Brain Science, 8, p. 549 Orgogozo, J. (1979) Activation of the SMA Science, 206, pp. 847-50 Passingham, R. (1996) Specialisation of the SMA Advances in Neurology, 70, pp. 105-16 Penfield, W. (1975) The Mystery of Mind Princeton University Press Penfield, W. & Welch, K. (1951) SMA: A clinical and experimental study Archives of Neurology and Psychology, 66, pp. 179-184 Ringo, J. (1985) Timing Volition Behavioural and Brain Sciences, 8, pp. 550-1 Rosenthal, D. (2002) Timing of conscious states Consciousness and Cognition, 11, pp. 215-20 Tanji, J. (1994) SMA in the cerebral cortex Neuroscience Research, 19, pp. 251-68 Zhu, J. Understanding volition Philosophical psychology Zhu, J. Locating volition Consciousness and cognition The Neuroscience of Movement Susan Pockett University of Auckland, Dept. of Physics In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 In this article Susan Pockett examines the connection between intentions and bodily movements. She emphasises that the brain has no obvious place for the initiation of action. However, the symptoms of Parkinson’s disease, where patients find that they can intend or will a movement, but not execute it, suggests that the substantia nigra in the basal ganglia is involved, since this area is damaged in Parkinson’s patients. However, Parkinson’s also causes a decrease in activity in the prefrontal, the supplementary motor area (SMA) and the pre-supplementary motor area (pre-SMA). Pockett distinguishes between ‘willed intentions’ and ‘sensorimotor intentions’. Willed intentions are defined as intentions accessible to consciousness, and this consists of plans to carry out a particular act. Data suggests that willed intentions are related to the dorsolateral prefrontal (DLPF) and the adjacent SMA and pre-SMA areas(1.-3.). By contrast other studies indicate that ‘sensorimotor intentions’ originate in the posterior parietal cortex(4.), and are defined as actions already decided on but not yet executed. The posterior parietal cortex is positioned at the end of the dorsal or ‘where’ stream of visual processing, and part of its output goes to the frontal motor areas. This stream is not associated with consciousness. By contrast, the ventral or ‘what’ stream of visual processing extends to the site of conscious visual perception in the infratemporal region. The existence of two very similarly created streams of visual processing, one conscious and one unconscious is interesting, because it at least implies a contradiction of those theories that suggest that consciousness is either the same thing as, or does not add anything to unconscious brain processing. It is not quite clear how these definitions relate to the Libet experiments, in which the readiness potential for an action was seen to emerge before the conscious awareness of the intention to act. In these experiments, the subjects had already been told to perform the action, and the only freedom was in the choice of exact timing. Pockett herself is rather critical of Libet’s experiments in this area. The Libet experiments were supposed to study the emergence of voluntary acts, but Pockett suggests that what is tested for is not voluntary action but randomness. The subjects were instructed to move a finger or wrist in their own time. Pockett suggests that they would have adjusted their brains to the very edge of activity, i.e. to the verge of flexing their fingers, leaving some chance neural event or fluctuation to tip it into actual activity. A study by Lau et al(3.) indicated a possibly distorting effect from subjects being told to attend to the intention to move, with resulting additional activity in the pre-SMA for up to three seconds before movement. Pockett makes a distinction between body movements that are responses to external cues, and self-initiated movements. Studies showed that self-initiated movements involve additional activity not found in externally cued activity. This additional activity takes place in the dorsolateral prefrontal and the anterior cingulate. Pockett regards the idea of activity flowing from the dorsolateral to the motor area as a reasonable assumption. Pockett accepts that simple voluntary acts such as flexing wrists or pressing buttons are activated unconsciously, and even movements to correct this initial movements are also seen as unconscious. However, she regards the case of complex decisions or decisions based on long-term intentions as unproven. It is noticeable that many papers simply ignore these type of decisions, or find some brief argument to side step them, preferring to focus on very simple acts, such as flexing fingers, despite the fact that they appear to be the most important aspect of the problem, with respect to the question of human freewill. Longer term intentions are formed in the dorsolateral prefrontal or pre-SMA, but it has not so far proved possible to develop experiments that link this process to consciousness. Pockett is somewhat apart from mainstream thinking in leaving the freewill question open, rather than using the Libet experiments as a thorough going disproof of freewill. References:- 1.) Jahanshahi, M. & Dirnberger, G. (1999) - The left dorsolateral prefrontal and random generation of responses - Neuropsychologia, 37: pp. 181-90 2.) Jahanshahi, M. et al, (2001) - Does the pre-frontal cortex contribute to movement related potentials - Neurocase, 7: pp. 495-501 3.) Lau, H. et al (2004) - Attention to intention - Science, 303: pp. 1208-1210 4.) Andersen, R. & Buneo, C. (2002) - Intentional maps in anterior parietal cortex - Annual Review of Neuroscience Free Choice & the Human Brain Richard Passingham & Hakwan Lau Dept. of Experimental Psychology, Oxford University Dept. of Psychology, Columbia University In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 The authors draw a distinction between actions that are the result of changes within the subject and actions that are prompted from outside or are specified by external cues. They have studied the brain mechanisms that lead up to these spontaneous or self-initiated actions. They have looked at the readiness potentials studied by both Libet and Kornhuber. These readiness potentials are present for spontaneous actions but not for those made in response to external cues. The earlier part of the readiness potential arises in the supplementary motor area (SMA) and pre-supplementary motor cortex (pre-SMA) before there is any activity in the motor cortex. Lesions that include the SMA, pre-SMA and the cingulate motor area that lies beneath these can cause a (usually temporary) failure to initiate movement or speech. An experiment by Lau et al (2004) (1.) showed that in a Libet type experiment there was more activity in the SMA if subjects attended to their intention to move rather than their actual movement. There was also more activity the earlier the intention was judged to have become conscious. Further experiments were deemed to show that this did not reflect some distortion of the memory of the intention coming into consciousness. The authors admit that experiments with finger movements deal with actions which are in any case partly automatic. They quote William James as saying that ‘will’ was to do with holding in mind an idea in the face of competing alternatives, and Frith et al described ‘willed action’ as choices that have to be attended to. Experiments that avoid simple stereotyped movements involve activity in the dorsal prefrontal, which did not occur when the same movements are in response to external cues. This activity was not considered to be explained by working memory or response preparation. The dorsolateral prefrontal is active when subjects must hold in mind and choose between a selection of items. However, when a task was performed without engaging attention, there was little activity in the dorsolateral prefrontal. It is the requirement to attend that engages the dorsal prefrontal. Rowe et al (2002)(2) showed that when subjects were attending to the selection of their actions there was an increase in the path strength between the dorsolateral prefrontal and the SMA. It is further pointed out that there is more activity in the dorsolateral prefrontal during explicit learning than implicit learning. The authors relate these findings to claims that the prefrontal as a whole is a kind of workspace for consciousness. This is slightly at variance with ideas that correlate consciousness to synchronous oscillations over large areas of the brain. The authors imply criticism of the realism of the Libet experiments in a way which echoes the criticisms made by Susan Pockett. They point out that Libet’s subjects were aware of the decision to flex their wrists well before they became aware of the specific timing of their action. In the real world, the equivalent of Libet’s instructions might be supplied by the subjects themselves, and it is the supply of these type of intentions that is interesting in respect of freewill. These intentional decisions are proposed to take place in the suggested global workspace. References:- 1.) Lau, H. et al (2004) - Attention to intention - Science, 303: pp. 1208-1210 2.) Rowe et al (2002b) - Attention to action in Parkinson’s disease - Brain, 125: pp. 276-289 Where’s the action? Epiphenomenalism and the problem of freewill. Shaun Gallagher Dept. of Philosophy, University of Central Florida In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 Gallagher regards the Libet approach to the freewill question as misguided. Freewill is considered to be a relatively long-term process that is not primarily spur of the moment, and cannot be squeezed into a few hundred milliseconds. He argues that we do not normally think in terms of freewill in relation to motor processes or even bodily movements aimed at achieving intentional acts but to the intentional acts themselves. Gallagher takes the rather strange example of his decision to capture a lizard for his lizard collection. He says that while Libet and some philosophers might concentrate attention on the bodily movement needed to capture the lizard, it is clear that the decision on such a movement is itself determined by the prior decision to capture the lizard. Thus, a person asked what they were doing during a lizard hunt, would not say that they were moving an arm or leg, but that they were trying to catch a lizard. Gallagher considers that enough time needs to be allowed for a certain type of conscious reflection, in order for freewill to be exercised. He takes the view that this conscious deliberation involves memory and knowledge (for instance about lizards) is not epiphenomenal but has a real effect on action. Empirical constraints on the problem of freewill Peter Ross Dept. of Philosophy, California State Polytechnic University In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 Ross criticises in particular Daniel Wegner’s experiments that are interpreted as showing that freewill must be an illusion. Wegner’s ‘I Spy’ experiment involves a subject moving a cursor on screen. The subject is told to stop the cursor at some point. Unknown to the subject another operator is able to override and stop the cursor before him. However, the experiment shows that the subject will often think that he has himself decided to stop the cursor. Ross, however, feels that the experiment is unrealistic in not representing the position of the subject where there is no such hidden human overrider. Ross argues that the fact that control may be illusory in some cases does not mean it is illusory in all cases. Ross also argues that Wegner’s experiment refers more to the sensations of freewill or mental causation rather than freewill itself. He distinguishes between the issue, on which Wegner concentrates, which involves a situation where a subject has an intention and is mistaken in thinking that it is the cause of some event, with the situation where the subject is not aware of the causes of intentions. Wegner has not addressed the latter. He further criticises Wegner for giving a lot of attention to pathological conditions such as ‘alien hand’ where the subject does not control his hand. Ross views this as not instructive as to how mental activity normally proceeds. It has to be said that the Wegner experiment has the feeling of something of a trick question devised to confirm a pre-existing metaphysical agenda, to the effect that consciousness could not be causal and freewill could not exist. Towards a dynamic theory of intentions Elizabeth Pacherie Institut Jean Nicod In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 Pacherie has similar criticisms of Wegner type arguments as those advanced by Peter Ross. She considers that the issue of whether mental states play a causal role and our actual experience of conscious control are being confused. She further argues that the Libet experiments fail to show that mental causation is illusory. She also distinguishes between being aware of the goal of actions, and being aware of the specific means of bringing the goal about. She points out that there is plenty of evidence in neuroscience that unconscious and conscious processes are different. Conscious and unconscious processes are regarded as being complementary in the production of voluntary actions. Pacherie attacks the widespread view that the Libet experiments represent a significant argument against goodwill. She argues that it is not necessarily true that only the first element in a causal chain can qualify as a cause. Even when the conscious intention comes later than the readiness potential this might not mean that consciousness has no causal role at all. She points out that a later experiment by Haggard & Eimer (1999) (1.) showed that while the readiness potential preceded consciousness, the lateralisation of the potential into the brain hemisphere that controlled the hand that was going to act, actually coincided with consciousness, and could be regarded as a correlate of consciousness. She also suggests that the fact that in the experiments the action was decided for the subject, and only the precise timing left open, undermines the claim of this, or similar experiments, to be relevant to goodwill. Pacherie is also critical of Wegner’s interpretation of an experiment of his, involving two people moving and stopping a cursor on a screen. The experiment showed that a subject could think that he has stopped a cursor, when someone else had in fact done it. Pacherie is not convinced that the fact that a subject can be effectively tricked into thinking that they have willed and caused an action performed by someone else, means that experience of willing is always illusory. References:- 1.) Haggard, P. & Eimer, M. (1999) - On the relations between brain potentials and the awareness of voluntary movement - Experimental Brain Research 126: pp. 128-133 Phenomenology & the feeling of doing: Wegner on the conscious will Tim Bayne Dept. of Philosophy, Oxford University In: Does Consciousness Cause Behaviour - Eds., Susan Pockett, William Banks & Shaun Gallagher - MIT Press, (2006) - ISBN: 978-0-262-16237-1 Bayne starts by summarising Wegner’s view of the conscious will. Wegner is seen as taking the view that conscious will is an introspective preview of actions before they are taken. Wegner also holds that conscious will is an illusion, which is here taken to mean that the sensation of conscious control is a misrepresentation of the actual causal path by which actions occur. In reply to this, Bayne refers us to the mid 20th century experiments of Wilder Penfield(1.). In the course of brain operations, Penfield directly stimulated the brains of conscious patients. This triggered a variety of actions on the part of the patients. However, the patients felt that they had not performed the actions, but instead that Penfield had somehow compelled their actions. This might be viewed as a fairly clear indication that there is a distinction between action preceded by a conscious intention, and actions produced by other means. However, Wegner tries to turn these experiments to some sort of advantage, pointing out that it is possible to perform an action, without experiencing oneself as the author or intender of the action. Bayne on the other hand compares the Penfield experiments to pathological conditions where patients move their hands in an uncontrolled way. He thinks it is not clear whether or not such actions have an author, and therefore we cannot be sure, in the way that Wegner appears to be, of the authorship of any of our actions. Wegner says that that the experience of consciously willing our actions happens when relevant thoughts occur just before actions are performed. Wegner does not attempt to say that actions are just motor commands, but focuses on the match between the agent’s beliefs or intentions, and the actions they are performing. Wegner is working at a personal or agency level. He says that conscious will is experienced, when prior conscious thoughts suggest that conscious will rather than the motor system drives actions. Bayne asks what is the relationship between the consciousness of a match between intentions and actions and the experience of performing the action. Bayne examines two of Wegner’s ‘trick question’ experiments, the first where subjects are trying to move a cursor, which is actually controlled by another operator, and another where they are primed with certain words, before being asked which of a range of words they authored. Bayne’s response is that all Wegner has done is to show that some experiences of actions as being controlled by intentions are false, rather than to show that all experiences of actions being controlled by experiences are false. What Bayne might also have said is that like other ‘illusion creation’ experiments or images that we find in consciousness studies, Wegner’s situations are very contrived and artificial relative to the conditions of normal life, let alone the conditions experienced by hunter-gatherers. For his part, Bayne seems to think that much activity is in fact automatic/non-conscious, but that one cannot argue from that to say that the experience of conscious will is an illusion. Neither Bayne nor Wegner ask the question which seems really pertinent to this debate, which is how to square the existence of conscious will and thought with evolution. As long as we operate within a scientific paradigm, the process of conscious thought has to involve the use of energy, probably quite a lot, as the brain is notoriously energy intensive, and it is very hard to see why evolution should have selected for a process that produced nothing but useless illusions. References:- 1.) Penfield, W. (1975) - The Mystery of Mind - Princeton University Press |
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