Over a long career, Libet has conducted experiments that have shown, in clear and concrete ways, how the brain produces conscious awareness.

Behav. and Brain Sci., 8, 558-566. Libet, B. (1987). 'Consciousness: Conscious, Subjective Experience.' In Encyclopedia of Neuroscience , ed. G. Adelman. ...

Evidence that led to the hypothesis of a backwards referral of conscious sensory experiences in time, and the experimental tests of its predictions, is summarized. Criticisms of the data and the conclusion by Churchland that this hypothesis is untenable are analysed and found to be based upon misconceptions and faulty evaluations of facts and theory. Subjective referral in time violates no neurophysiological principles or data and is compatible with the theory of "mental" and "physical" correspondence.

Commentary on John Searle's Article John Searle presents a philosopher's view of how conscious experience and free action relate to brain function. That view demands an examination by a neuroscientist who has experimentally investigated this issue.

The chief goal of Velmans' article is to find a way to solve the problem of how conscious experience could have bodily effects. I shall discuss his treatment of this below. First, I would like to deal with Velmans' treatment of my own studies of volition and free will in relation to brain processes. Unconscious Initiation and Conscious Veto of Freely Voluntary Acts Velmans appropriately refers to our experimental study that found that onset of an electrically observable cerebral process preceded (...) the appearance of the subject's awareness of the conscious wish to act, by at least 350 msec. That indicated that the volitional process is initiated unconsciously. Velmans uses the term preconscious instead of unconscious. But, in fact, subjects have no reportable awareness or intuitive feeling that the brain has started a process before their conscious wish/urge to act appears. Unconscious initiation of the voluntary process appeared to mean that conscious free will could not actually 'tell' the brain to begin its preparation to carry out a voluntary act. (shrink)

Voluntary acts are preceded by electrophysiological (RPs). With spontaneous acts involving no preplanning, the main negative RP shift begins at about200 ms. Control experiments, in which a skin stimulus was timed (S), helped evaluate each subject's error in reporting the clock times for awareness of any perceived event.

The paper begins by contrasting the unitary nature of conscious experience with the demonstrable localization of neural events. Philosophers and neuroscientists have developed models to account for this paradox, but they have yet to be tested empirically. The author proposes a `Conscious Mental Field', which is produced by, but is phenomenologically distinct from, brain activity. The hypothesis is, in principle, open to experimental verification. The paper suggests appropriate surgical procedures and some of the difficulties that would need to be overcome (...) in such an experiment. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Commentary on “Free Will in the Light of Neuropsychiatry”Benjamin Libet (bio)Is Free Will Incompatible with Neuroscience?Sean Spence sets forth some interesting approaches to the issue of free will. His concepts are provocative and his marshalling of related quotations is informative.However, I shall argue with some of his crucial assumptions, in a way that affects the validity of some of Spence’s major conclusions. The latter are that “conscious experience (...) is always temporally postneural activity and thus... ‘caused’ not causal. Our ‘control’ is a sense which may be lost.... Our sense of agency is apparently illusory.”I have, of course, no quarrel with the view that even a fully voluntary act is initiated unconsciously (non-consciously). That condition was in fact demonstrated experimentally by us (Libet et al. 1983) when we found that cerebral neural activity (“readiness potential”) precedes the subject’s awareness of his/her intention or wish to act by at least 350 msec. This applied to fully self-initiated acts that occurred without “pre-planning” by the subject of when to move. (Incidentally, those finding have been replicated by others—see Keller and Heckhansen, 1990 with commentary thereon by Libet 1992, and Wong et al. 1988).However, we also found that conscious intention did precede that actual motor act by about 200 msec. That left open the potentiality for the conscious function to control the outcome of the process that was initiated in the brain unconsciously (see Libet 1985). We have all had the experience of consciously suppressing or vetoing the performance of an urge or intention to act. The 200 msec interval provides sufficient time in which the voluntary process could be stopped, before final activation of the motor area about 50 msec before the act. We were able to show that subjects could veto an act in the 100–200 msec interval before the expected time for the action.Spence dismisses this free will potentiality in the control or veto of a voluntary process. He says: “It is flawed because the ‘decision’ (in consciousness) to act or not to act is itself the ‘result’ of preceding neural activity.” This argument is based on my own evidence that a period of up to 500 msec of cerebral activity is required to produce a conscious sensory experience (Libet 1993, for review).But conscious control of a process is not the same as becoming aware of the volitional intent (Libet 1985, 563–564). Control implies the imposing of a change, in this case after the appearance of the awareness of intention to act. Conscious control may not necessarily require the same neural “time-on” feature that precedes the appearance of awareness per se. There is presently [End Page 95] no directly applicable evidence against the appearance of a conscious control function without prior neural processes specific to its initiation.In short, one cannot cavalierly dismiss the possibility of a conscious free will function on the basis of a belief that such a control function must be itself initiated unconsciously by prior specific neural processes. The argument that conscious free will control is simply a useful delusion must still be regarded as a philosophical belief, not a scientifically demonstrated proposition.Spence goes on to suggest that “Consciousness is necessary for purposeful (intentional) action but it is not the initiator.” But if Spence is consistent in his view that all conscious functions are preceded by specific neural activities that initiate the function, then his putative role for consciousness would have been itself initiated unconsciously. How, then, would consciousness be “performing (purposeful, intentional) actions with subtlety and invention” if it is simply an after-effect of the responsible cerebral process? It would appear that Spence is postulating an active role for consciousness in directing the course of neural activities carrying out purposeful, intentional actions. That is the kind of potentiality I was suggesting must be kept open, but one that Spence dismissed elsewhere as “flawed.”On a technical point: The Grey Walter experiment is cited as evidence for postulated effects of timing, in the “illusion” of self-initiation of an act. However, that experimental result was simply due to the fact that the motor cortex initiates the command... (shrink)

Sensation elicited by a skin stimulus was subjectively reported to feel stronger when followed by a stimulus to somatosensory cerebral cortex , even when C was delayed by up to 400 ms or more. This expands the potentiality for retroactive effects beyond that previously known as backward masking. It also demonstrates that the content of a sensory experience can be altered by another cerebral input introduced after the sensory signal arrives at the cortex. The long effective S-C intervals support the (...) thesis that a duration of cortical activity of up to 0.5 s is required before awareness of a sensory stimulus is developed. (shrink)

Solutions to the ‘hard problem’ of consciousness must accept conscious experience as a fundamental non-reducible phenomenon in nature, as Chalmers suggests. Chalmers proposes candidates for an acceptable theory, but I find basic flaws in these. Our own experimental investigations of brain processes causally involved in the development of conscious experience appear to meet Chalmers’ requirement. Even more directly, I had previously proposed a hypothetical ‘conscious mental field’ as an emergent property of appropriate neural activities, with the attributes of integrated subjective (...) experience and a causal ability to modulate some neural processes. This theory meets all the requirements imposed by the ‘hard problem’ and, significantly, it is experimentally testable. (shrink)

The problem of free will lies at the heart of modern scientific studies of consciousness. An influential series of experiments by Libet has suggested that conscious intentions arise as a result of brain activity. This contrasts with traditional concepts of free will, in which the mind controls the body. A more recent study by Haggard and Eimer has further examined the relation between intention and brain processes, concluding that conscious awareness of intention is linked to the choice or selection (...) of a specific action, and not to the earliest initiation of action processes. The exchange of views in this paper further explores the relation between conscious intention and brain activity. (shrink)

People have disagreed on the significance of Libet-style experiments for discussions about free will. In what specifically concerns free will in a libertarian sense, some argue that Libet-style experiments pose a threat to its existence by providing support to the claim that decisions are determined by unconscious brain events. Others disagree by claiming that determinism, in a sense that conflicts with libertarian free will, cannot be established by sciences other than fundamental physics. This paper rejects both positions. First, (...) it is argued that neuroscience and psychology could in principle provide support for milder deterministic claims that would also conflict with libertarian free will. Second, it is argued that Libet-style experiments—due to some of their peculiar features, ones that need not be shared by neuroscience as a whole—currently do not support such less demanding deterministic claims. The general result is that neuroscience and psychology could in principle... (shrink)

Free will, which is dealt with under the title of "acts of the servants" in the Kalām literature, is one of the fundamental issues of the science of Kalām. Benjamin Libet's famous experiment, which he conducted in order to seek an answer to the question of free will, caused the free will debates to move to the field of neuroscience. The logic of Libet's experiment is to compare the neural activity in the brain with the moment (...) when a person is conscious while performing a voluntary act. In Libet's subjects, it was observed that brain activity in the decision-making process started at the moment of unconsciousness. The results of this experiment have long been interpreted in neuroscience as showing that free will is an illusion. Although Libet claimed that conscious intention creates a veto effect by stopping the action at the last moment, recent studies have shown that Libet's veto solution for free will does not work. The most vocal critics of the implications of the Libet experiment from the beginning have generally been philosophers. In this article, the criticisms of the Libet experiments by names such as Marcel Brass, Alfred Mele, and Peter Ulric Tse are presented. However, especially in recent years, neuroscientist Aaron Schurger's experimental and mathematical reinterpretation of the concept of readiness potential, which is key for Libet, and his proposal of an alternative model are mentioned. The article discusses Schurger's claim that the readiness potential may not actually reflect a brain that is ready. According to Schurger, the readiness potential is just random fluctuations that already exist in the brain and is not the sole cause of decisions. In fact, it has been argued that the readiness potential is related to neural noise in the brain rather than to the decision-making process. Thanks to Schurger's critique and the new model, it became clear that the Libet experiment did not rule out free will. But it does not constitute a proof of free will either. While the subject remains a mystery, it is unthinkable for Kalām to remain aloof from these debates. The article also touches upon the views of the Jabriyya, Ash'ariyya, Maturidiyya and Mu'tazilah in Kalām regarding the acts of the servants and questions what the Libet experiment can mean for these schools. Accordingly, while Jabriyya, with its deterministic view, may correspond to an erroneous interpretation of the Libet experiment, Mutazila may be the school that will have the most difficulty in explaining the Libet experiment. As a result, it seems that the views that consider both human agency and God's creation in voluntary acts are the most accurate. Moreover, despite the lack of a clear explanation of the theory of kasb in the Ash'ariyya, the Maturidiyya's assertion that the juz'i will is uncreated and that two influences affect voluntary acts suggests that this school provides the most solid foundation for free will. In order for such discussions to proceed on a healthy basis, it is very important to follow multidisciplinary methods. In addition, as much as Kalāmists should approach scientific studies seriously, it is important that they do not adopt a completely submissive attitude in the face of scientific claims, and that they learn the relevant critiques from experts in the field. Only in this way, we believe that the scientific inferences to be made will be based on a solid ground and that Kalāmists can make serious contributions to the solution. (shrink)

In my paper, I spell out which types of libertarian theories can be refuted by Libet-style experiments and which cannot. I claim that, on the one hand, some forms of deliberative libertarianism and restrictive libertarianism cannot even in principle be denied on the basis of these experiments; and on the other hand, standard libertarianism, along with some versions of restrictive and deliberative libertarianism, can in principle be refuted by these experiments. However, any form of restrictive libertarianism can be refuted (...) in the future only if researchers perform new and “untraditional” Libet-style experiments. This is because “traditional” Libet-style experiments investigate decisions in Buridan-type situations. But these decisions are irrelevant with regard to free will, according to the restrictivists. -/- In the first section, I clarify some terminological issues in order to set the stage for a precise analysis. In the second, I attempt to show what the main reason is for thinking that Libet-style experiments seem to be problematic for libertarian theories. Although showing that actions are unconsciously initiated does not pose a real challenge for the elaborated philosophical theories of free will, Libet-style experiments may be problematic for most libertarian theories because, pace Roskies and Nahmias, libertarians have good reasons for saying that local determinism and free will are incompatible. In the third section, I argue that because some versions of deliberative libertarianism do not claim that decisions about actions are the center of freedom-relevant indeterminism, Libet-style experiments are unable to refute them after all. In the fourth, I attempt to show why standard centered libertarianism according to which there are no relevant metaphysical differences between different types of conscious decisions is in principle vulnerable to Libet-style experiments to a greater extent. Fifth, I point out the reasons why restrictivist centered libertarianism is less vulnerable to these experiments. Still, I argue that moderate-restrictivism can in principle be denied by Libet-style experiments if these experiments are modified in an important respect. However, proponents of hard-restrictivism should not worry about the possible results of these experiments because these theories restrict the set of free decisions to such a great extent that they cannot be subjected to a proper empirical test. (shrink)

The neurological experiments conducted by Benjamin Libet (1985) and Grey Walter (1993, in Dennett) provide evidence that our actions are caused by non-conscious brain events beyond our conscious awareness. Normally, we assume that our conscious choices lead us to do things. If these researchers have interpreted their evidence correctly, it may be that we lack free-will, for we could not control a non-conscious brain state. Libet however provides evidence that agents can “change their minds” just before performing some (...) action. He felt that this was the elbow-room for free-will. But it may be inconsistent for him to suggest this, since his evidence indicates that there is no room for conscious choice. In this paper we discuss these results and various objections to the interpretation of the work. South African Journal of Philosophy Vol. 26 (3) 2007: pp. 271-288. (shrink)

Epiphenomenalism is the thesis that though physical events may cause mental events, those mental events never cause physical events. In this paper, I will be concerned with the claim that our thoughts, intentions, and awareness play no causal role in producing actions. Though epiphenomenalism has been defended with a priori philosophical arguments, the majority of the support that it has gained in recent years has come from advances in neuroscience. At the center of these experiments is the Libet paradigm (...) that aims to show that our actions are initiated by unconscious brain processes prior to our awareness of the intention or decision to perform the corresponding actions. It has been widely suggested that these studies support the view that consciousness is epiphenomenal, and if Libet-style experiments support this conclusion, the results have direct implications for free will. I argue by way of a dilemma that any study that relies on reports of subjects’ awareness in its methodology cannot be used to support epiphenomenalism because the experimenters would have to rule out the possibility that consciousness plays a causal role in order to do so. (shrink)

Many neuroscientific experiments, based on monitoring brain activity, suggest that it is possible to predict the conscious intention/choice/decision of an agent before he himself knows that. Some neuroscientists and philosophers interpret the results of these experiments as showing that free will is an illusion, since it is the brain and not the conscious mind that intends/chooses/decides. Assuming that the methods and results of these experiments are reliable the question is if they really show that free will is an illusion. To (...) address this problem, I argue that first it is needed to answer three questions related to the relationship between conscious mind and brain: 1. Do brain events cause conscious events? 2. Do conscious events cause brain events? 3. Who is the agent, that is, who consciously intends/chooses/ decides, the conscious mind, the brain, or both? I answer these questions by arguing that the conscious mind is a property of the brain due to which the brain has the causal capacity to interact adaptively with its body, and trough the body, with the physical and sociocultural environment. In other words, the brain is the agent and the conscious mind, in its various forms - cognitive, volitional and emotional - and contents, is its guide of action. Based on this general view I argue that the experiments aforementioned do not show that free will is an illusion, and as a starting point for examining this problem I point out, from some exemplary situations, what I believe to be some of the necessary conditions for free will.Key-words: Agent brain, conscious mind, free will, Libet-style experiments. (shrink)

An extended examination of Libet's works led to a comprehensive reinterpretation of his results. According to this reinterpretation, the Minimum Train Duration of electrical brain stimulation should be considered as the time needed to create a brain stimulus efficient for producing conscious sensation and not as a basis for inferring the latency for conscious sensation of peripheral origin. Latency for conscious sensation with brain stimulation may occurafterthe Minimum Train Duration. Backward masking with cortical stimuli suggests a 125-300 ms minimum (...) value for the latency for conscious sensation of threshold skin stimuli. Backward enhancement is not suitable for inferring this latency. For determining temporal relations between stimuli that correspond to subjects' reports, theendof cerebral Minimum Train Duration should be used as reference, rather than its onset. Results of coupling peripheral and cortical stimuli are explained by a latency after the cortical Minimum Train Duration, having roughly the same duration as the latency for supraliminal skin stimuli. Results of coupling peripheral stimuli and stimuli to medial lemniscus (LM) are explained by a shorter LM latency and/or a longer peripheral latency. This interpretation suggests a 230 ms minimum value for the latency for conscious sensation of somatosensory near-threshold stimuli. The backward referral hypothesis, as formulated by Libet, should not be retained. Long readiness potentials preceding spontaneous conscious or nonconscious movements suggest that both kinds of movement are nonconsciously initiated. The validity of Libet's measures of W and M moments (Libet et al., 1983a) is questionable due to problems involving latencies, training, and introspective distinction of W and M. Veto of intended actions may be initially nonconscious but dependent on conscious awareness. (shrink)

Benjamin Libet compared the perceived time of direct brain stimulation to the perceived time of skin stimulation. His results are among the most controversial experiments at the interface between psychology and philosophy. The new element that I bring to this discussion is a reanalysis of Libet's raw data. Libet's original data were difficult to interpret because of the manner in which they were presented in tables. Plotting the data as psychometric functions shows that the observers have great (...) uncertainty about the relative timing of events, as seen the shallow psychometric slopes. A second indication of uncertainty comes from Libet's use of three response categories, A first; B first; and A and B simultaneous. The large number of “perceptually simultaneous” responses provides a further measure of the difficulty of the judgment. There are thus a very broad range of stimulus delays in which the subject is unable to make an accurate ordering response. These points provide evidence that there is no compelling reason to invent exotic or ad hoc mechanisms to account for Libet's data since the uncertainty window is large enough to allow simple mechanism such as memory shifts. Libet argued that his data provide evidence for a backward referral in time. I argue that even though Libet's own data are weak, there are good arguments for a backward referral mechanism to help the subject make sense out of the tangled chaos of asynchronous information associated with experienced events. (shrink)

Abstract : Libet’s famous experiments, showing that apparently we become aware of our intention to act only after we have unconsciously formed it, have widely been taken to show that there is no such thing as free will. If we are not conscious of the formation of our intentions, many people think, we do not exercise the right kind of control over them. I argue that the claim this view presupposes, that only consciously initiated actions could be free, places (...) a condition upon freedom of action which it is in principle impossible to fulfil, for reasons that are conceptual and not merely contingent. Exercising this kind of control would require that we control our control system, which would simply cause the same problem to arise at a higher-level or initiate an infinite regress of controllings. If the unconscious initiation of actions, as well as the takings of decisions, is incompatible with control over them, then free will is impossible on conceptual grounds. Thus, Libet’s experiments do not constitute a separate, empirical, challenge to our freedom. (shrink)

The readiness potential (RP) is one of the most controversial topics in neuroscience and philosophy due to its perceived relevance to the role of conscious willing in action. Libet and colleagues reported that RP onset precedes both volitional movement and conscious awareness of willing that movement, suggesting that the experience of conscious will may not cause volitional movement (Libet, Gleason, Wright, & Pearl, 1983). Rather, they suggested that the RP indexes unconscious processes that may actually cause both volitional (...) movement and the accompanying conscious feeling of will (Libet et al., 1983; pg. 640). Here, we demonstrate that volitional movement can occur without an accompanying feeling of will. We additionally show that the neural processes indexed by RPs are insufficient to cause the experience of conscious willing. Specifically, RPs still occur when subjects make self-timed, endogenously-initiated movements due to a post-hypnotic suggestion, without a conscious feeling of having willed those movements. (shrink)

Saigle, Dubljevic, and Racine (2018) claim that Libet-style experiments are insufficient to challenge that agents have free will. They support this with evidence from experimen- tal psychology that the folk concept of freedom is consis- tent with monism, that our minds are identical to our brains. However, recent literature suggests that evidence from experimental psychology is less than determinate in this regard, and that folk intuitions are too unrefined as to provide guidance on metaphysical issues like monism. In light (...) of this, it is worthwhile to examine the authors’ insuf- ficiency claim under the assumption that monism is false and dualism true (our minds are not identical to our brains). We conclude that, were dualism true, then Libet- style experiments would tell us no more about freedom and moral responsibility than what the authors initially claimed, thus further bolstering their point that Libet-style experiments are ill-suited to speak to the free will of agents. In what follows we first discuss some of the reasons to be skeptical of using folk intuitions to make claims about the nature of freedom and moral responsibility. We then draw from the work of E. J. Lowe to demonstrate that Libet-style experiments would likely give the same results regardless of the truth of monism or dualism. (shrink)

This issue of Consciousness and Cognition presents four target articles and eight commentaries on the target articles. The present article presents comments on those commentaries, grouped into backward referral and volition categories. Regarding backward referral: I disagree with my fellow commentators and take the unpopular position of defending Libet's notion of backward referral. I join my fellow commentators in critiquing Libet's notion of a 500-ms delay. I examine several of the hypotheses suggested by other commentators for why cortical (...) and lateral meniscus stimulation give very different timing results. I suggest a simple experiment to help discriminate among the hypotheses. I comment on why temporal reordering is more likely to occur late rather than early in mental processing. Regarding Libet's volition experiments, I ask what is the root of the controversy, given the general agreement on the data. I agree with a commentator that Libet's chronotheology rather than his chronoscience is the cause of much of the controversy. Rather than joining others in criticizing Libet for his chronotheology I point out that he is making a respectable philosophical point regarding nondeterministic Free Will, but one that is easily misunderstood. I discuss two ways by which Libet's viewpoint can be brought into mainstream science. (shrink)

Based on his experimental studies, Libet claims that voluntary actions are initiated by unconscious brain activities well before intentions or decisions to act are consciously experienced by people. This account conflicts with our common-sense conception of human agency, in which people consciously and intentionally exert volitions or acts of will to initiate voluntary actions. This paper offers an alternative interpretation of Libet's experiment. The cause of the intentional acts performed by the subjects in Libet's experiment (...) should not be exclusively attributed to special cerebral processes; conscious intentions formed at the beginning of the experiment, when the subjects received experimental instructions, must be taken into account. In addition, what the subjects were required to report was not a conscious intention or decision to act that conventionally figures in the etiology of voluntary action, but rather a perceived effective urge to move induced by specific experimental instructions. According to the alternative interpretation, the most suitable mental term correlated with the specific brain activity that precedes conscious, self-initiated voluntary bodily movements is volition. This account is supported by recent theories of function of the supplementary motor area . Therefore, the notion that we are the authors or originators of our own actions, which is fundamental to our common understanding of free will, moral responsibility and human dignity, can be preserved. (shrink)

With certain topics the general reader experiences a double-whammy wherein one must peer through a curtain of needlessly obscure jargon to try glimpsing something that is inherently weird in nature. Bell’s nonlocality was once such a topic, but authors have had considerable success over the years in showing where the line is between the enigma itself and the human-made oddities surrounding it . Libet-ology has yet to undergo that de-mystifying process. Accordingly, our first order of business here is to (...) restate its basic tenets in plain English so that only nature’s inherent puzzle is left on the table, free of certain peculiarities of the existing technical literature. We also address the question of the central topic versus its byways, as alluded to by ‘left turn into veto-as-volition’ in our title. In the ensuing parts of the paper, we look outside the field to see how hypnotherapy and Hinduism might shed light on it. (shrink)

The meaning and significance of Benjamin Libet’s studies on the timing of conscious will have been widely discussed, especially by those wishing to draw sceptical conclusions about conscious agency and free will. However, certain important correctives for thinking about mental states and processes undermine the apparent simplicity and logic of Libet’s data. The appropriateness, relevance and ecological validity of Libet’s methods are further undermined by considerations of how we ought to characterise intentional actions, conscious intention, and what (...) it means to act with conscious intent. Recent extensions of Libet’s paradigm using fMRI and decision-based tasks suffer from similar limitations. The result is that these sorts of laboratory studies of isolated, trivial, decontextualized bodily movements, in a context of extended (conscious) intentional experimental participation and cooperation, are of dubious and potentially misleading relevance to the study of agency. (shrink)

It is sometimes suggested that if, whenever we act intentionally, we do, or try to do, what we are most strongly motivated to do at the time, then we are at the mercy of whatever desire happens to be strongest at the time. I have argued elsewhere that this is false (Mele 1987, ch. 5; 1992, ch. 4; 1995, ch. 3; 1996). This essay provides another route to that conclusion, but that is not my primary aim. The goal of this (...) paper is to display the bearing of some well-known experiments by physiologist Benjamin Libet on this issue. Philosophical discussion of these experiments has focused on Libet's claims about consciousness. The significance of these experiments for the topics of motivation and agential control also merits serious attention. (shrink)