Grice and the Brain

The wiki's "Neuroscience of free will" entry refers to recent neuroscientific investigations shedding light on the question of free will, which is a philosophical and scientific question as to whether, and in what sense, rational agents exercise control over their actions or decisions.

As it has become possible to study the living brain, researchers have begun to watch decision-making processes at work.

The field itself remains highly controversial as there is no consensus among researchers about the significance of findings, their meaning, or what conclusions may be drawn.

In the light of recent studies, there lies a possibility that the experience of "will" requires re-conceptualization.

While this would carry implications for moral responsibility in general, the research below is still new enough to warrant only tentative conclusions.

How and whether consciousness directly initiates, or even moderates behaviour remains unclear.

One significant finding of these studies is that a person's brain seems to commit to certain decisions before the person becomes aware of having made them.

Early studies found delays of about half a second.

With contemporary brain scanning technology, scientists in 2008 were able to predict with 60% accuracy whether subjects would press a button with their left or right hand up to 10 seconds before the subject became aware of having made that choice.[1]

These findings may not be sufficient to contradict free will, as it would be quite likely that a large range of cognitive operations are necessary to freely press a button.

Another proposed explanation is a 'forward model of motor control'.

The idea is that our conscious self does not cause all behaviours.

Instead, the conscious self is alerted (through various sensations) to behaviours that the rest of the brain and body are already planning and performing.

To be clear, this model does not deny that consciousness affects behaviour.

It does not forbid conscious experience from being used as input by unconscious processes - information that might modify a behaviour in progress.

The key is that the unconscious processes play a much larger role in behaviour.

This model thus challenges some conceptions of free will, since self-awareness may only recognize a feeling of will, which appears before an action.

One possibility is that both feelings of intention and actual behaviors are on a sort of parallel circuit, both emerging from brain processing outside of awareness.

It may be possible, then, that our intuitions about the role of our conscious "intentions" have led us astray.

It may be the case that we have confused correlation with causation by believing that conscious awareness necessarily causes the body's movement.

This possibility is bolstered by various introspection illusions - studies showing that humans do not have full access to various internal processes.

The discovery that humans possess a determined will would have implications for moral responsibility.

Neuroscientist and author Sam Harris believes this is the case, suggesting

"Thoughts simply arise in the brain. What else could they do? The truth about us is even stranger than we may suppose: The illusion of free will is itself an illusion"[2].

There have been a number of problems regarding studies of free will[3].

Particularly in earlier studies, research relies too much on the introspection of the participants (other research shows that things such as introspective estimates of event timing are not accurate).

The conscious decision may be made elsewhere in the brain before conscious realization, leaving room for free will even if the conscious realization comes delayed[3].

The brain activity measures have been insufficient and primitive as there is no good independent brain-function measure of the conscious generation of intentions, choices, or decisions; the conclusions drawn from measurements that have been made are debatable too, as they don't necessarily tell, for example, what a sudden dip in the readings are representing.

In other words, the dip might have nothing to do with unconscious decision, since many other mental processes are going on while performing the task.[3]

These studies have therefore only just begun to shed light on the role that consciousness plays in actions and it is too early to draw very strong conclusions.

It is worth noting that such experiments - so far - have dealt only with free will decisions made in short time frames (seconds) and may not have direct bearing on free will decisions made ("thoughtfully") by the subject over the course of many seconds, minutes, hours or longer.

A pioneering experiment in this field was conducted by 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).

Although it was well known that the readiness potential preceded the physical action, Libet asked how the readiness potential corresponded to the felt intention to move.

To determine when the subject felt the intention to move, he asked her to watch the second hand of a clock and report its position when she felt that she had felt the conscious will to move.[4]

The "Libet Clock", used by having the subject memorize the position of the dot when something occurs (in this case, when they feel the urge to move).

Libet found that the unconscious brain activity leading up to the conscious decision by the subject to flick his or her wrist began approximately half a second before the subject consciously felt that she had decided to move.[4][5]

Libet's findings suggest that decisions made by a subject are first being made on a subconscious level and only afterward being translated into a "conscious decision", and that the subject's belief that it occurred at the behest of her will was only due to her retrospective perspective on the event.

The interpretation of these findings has been criticized by Daniel Dennett, who argues that people will have to shift their attention from their intention to the clock, and that this introduces temporal mismatches between the felt experience of will and the perceived position of the clock hand.[6][7]

Consistent with this argument, subsequent studies have shown that the exact numerical value varies depending on attention.[8][9]

Despite the differences in the exact numerical value, however, the main finding has held.[10][11][12]

Mele criticizes this design for other reasons. Having attempted the experiment himself, Mele explains that "the awareness of the intention to move" is an ambiguous feeling at best. For this reason he remained skeptical of interpreting the subjects' reported times for comparison with their 'readiness potential'.[13]

In a variation of this task, Haggard and Eimer asked subjects to decide not only when to move their hands, but also to decide which hand to move.

In this case, the felt intention correlated much more closely with the "lateralized readiness potential" (LRP), an ERP component which measures the difference between left and right hemisphere brain activity.

Haggard and Eimer argue that the feeling of conscious will therefore must follow the decision of which hand to move, since the LRP reflects the decision to lift a particular hand.[8]

A more direct test of the relationship between the readiness potential and the "awareness of the intention to move" was conducted by Banks and Isham (2009).

In their study, participants performed a variant of the Libet's paradigm in which a delayed tone followed the button press.

Subsequently, research participants reported the time of their intention to act (e.g., Libet's "W"). If W were time-locked to the readiness potential, W would remain uninfluenced by any post-action information. However, findings from this study show that W in fact shift systematically with the time of the tone presentation, implicating that W is, at least in part, retrospectively reconstructed rather than pre-determined by the readiness potential.[14]

A study conducted by Jeff Miller and Judy Trevena (2009)[15] suggests that the readiness potential (RP) signal in Libet's experiments doesn't represent a decision to move, but that it's merely a sign that the brain is paying attention.

In this experiment the classical Libet experiment was modified by playing an audio tone indicating to volunteers to decide whether to tap a key or not. The researchers found that there was the same RP signal in both cases, regardless of whether or not volunteers actually elected to tap, which suggests that the RP signal doesn't indicate that a decision has been made[16]. In a second experiment they asked volunteers to decide on the spot whether to use left hand or right to tap the key while monitoring their brain signals, and they found no correlation among the signals and the chosen hand. This criticism has itself been criticized by free-will researcher Patrick Haggard, who mentions literature that distinguishes two different circuits in the brain that lead to action: a "stimulus-response" circuit and a "voluntary" circuit. According to Haggard, researchers applying external stimuli are testing neither the voluntary circuit, nor Libet's hypothesis about internally triggered actions[17].

A recent study by Masao Matsuhashi and Mark Hallett [18] claims to have replicated Libet's findings without relying on subjective report or clock memorization on the part of participants. The authors believe that their method can identify the time (T) at which a subject becomes aware of her own movement. Matsuhashi and Hallet argue that this time not only varies, but often occurs after early phases of movement genesis have already begun (as measured by the readiness potential). They conclude that a person's awareness cannot be the cause of movement, and may instead only notice the movement.

It was difficult to identify exactly when a person becomes aware of their action. Surprisingly, awareness seems to come only after actions have already begun in the brainMatsuhashi and Hallett's study can be summarized thus:

Hypothesis: If our conscious intention is what causes movement genesis, conscious intention should always occur before any movement has begun. This is because otherwise, if we become aware of a movement only after it has already been started, our awareness is obviously not the cause of that movement.

Experiment: Have subjects perform self-paced finger movements while "stop-signal" sounds play randomly. The subject must stop his movement if he hears a signal while he is aware of any intention to move. Whenever there is an action, graph any tones that occurred before that action. The graph will show tones at only 2 points: (a) before the subject is even aware of her movement genesis (or else she would have stopped the movement), as well as (b) after it is too late to stop the action (called the point of no return - of little importance here). As seen in the histogram above, now the researchers know exactly how many seconds before most actions the subject normally becomes aware: This moment of awareness, dubbed "T", can be found by looking at the border between tones and no tones. In other words, time T is found by looking to see when tones started resulting in vetoed actions (and an empty graph, since we only graphed the tone if there was an action). That is how we estimate the timing of the conscious intention to move without relying on the subject's knowledge or demanding them to focus on a clock. The last step is to compare time T to ERP measures of when their finger movements begin.
Results: The time of the conscious intention to move T normally occurred too late to be the cause of movement genesis (again, see the example of a subject's histogram on the right. Although it is not shown, this subject's readiness potentials tells us that his actions start at -2.8 seconds, any yet this is even before his time "T").
Conclusion: The feeling of the conscious intention to move does not cause movement genesis; both the feeling of intention and the movement itself are the result of unconscious processing. [18]

A simple "signalling noise" is used, but it is to warn participants that they must prevent any actions they are aware ofIn this new study, volunteers were again asked to perform finger extensions in short, self-paced intervals. In this version of the experiment, researchers introduced randomly timed “stop tones” during the self paced movements. If participants were not conscious of any intention to move, they simply ignored the tone. On the other hand, if they were aware of their intention to move at the time of the tone, they had to try and veto the action, then relax for a bit before continuing self paced movements. This experimental design allowed Matsuhashi and Hallet to see when, once the subject moved their finger, any tones occurred. The goal was to identify their own equivalent of Libet’s W, their own estimation of the timing of the conscious intention to move, which they called “T”.

Testing the hypothesis that conscious intention occurs after movement genesis has already begun required the researchers to analyse the distribution of tones before actions. The idea is that, after time T, tones will lead to vetoing and thus a reduced representation in the data. There would also be a point of no return P where a tone was too close to the movement onset for the movement to be vetoed. In other words, the researchers were expecting to see many tones (when the subjects are not yet aware of their movement genesis), followed by a drop in the appearance of tones during a certain period of time (where the subjects are conscious of their intention and would stop any movement), and finally an increase again in tones (when the subjects do not have the time to process the tone and prevent an action). That is exactly what the researchers found (see the histogram in the top left).

Graphing tones as they appeared (or didn't) in the time before any action. In this case, researchers believe the subject becomes aware of his/her actions at about -1.769 seconds (this is time 'T'). A typical, strange example: this subject's brain scans suggest movement preparation as early as -2.8 seconds.Let's look at when tones can be seen before Subject A moved, for example. He or she showed many tones on average up until 1.8 seconds before movement onset, but a significant decrease in tones immediately after that time. Presumably this is because the subject usually became aware of his or her intention to move at -1.8 seconds, which is then labelled point T. Since most actions are vetoed if a tone occurs after point T, there are very few tones represented during that range. Finally, there is a sudden increase in the number of tones appearing before an action at -0.1 seconds: meaning this subject has passed point P. Matsuhashi and Hallet were thus able to establish an average time T (-1.42 seconds) and P without subjective report, and compare it to EEG measurements of movement (which begin at about -2.8 seconds). In the end, since T — like Libet’s original W — was often found after movement genesis had already begun, the authors concluded that the generation of awareness occurs afterwards or in parallel to action, but most importantly, it is probably not the cause.[18]

Note that these results were gathered using finger movements, and may not necessarily generalize to other actions such as thinking, or even other motor actions in different situations. Indeed, the human act of Planning has implications for free will and so this ability must also be explained by any theories of unconscious decision making. Philosopher Alfred Mele, although he has expressed views that amount to determinism, also doubts the conclusions of these studies. He explains that simply because a movement may have been initiated before our "conscious self" has become aware of it does not mean our consciousness does not still get to approve, modify, and perhaps cancel (called vetoing) the action. [19]

[edit] Manipulating the unconscious
Transcranial Magnetic Stimulation uses magnetism to safely stimulate or inhibit parts of the brain.Related experiments showed that neurostimulation could affect which hands people move, even though the experience of free will was intact. Ammon and Gandevia found that it was possible to influence which hand people move by stimulating frontal regions that are involved in movement planning using transcranial magnetic stimulation in either the left or right hemisphere of the brain.[20]

Scientists were able to change which hand subjects normally chose to move without subjects noticing the influenceRight-handed people would normally choose to move their right hand 60% of the time, but when the right hemisphere was stimulated they would instead choose their left hand 80% of the time (recall that the right hemisphere of the brain is responsible for the left side of the body, and the left hemisphere for the right). Despite the external influence on their decision-making, the subjects continued to report that they believed their choice of hand had been made freely. In a follow-up experiment, Alvaro Pascual-Leone and colleagues found similar results, but also noted that the transcranial magnetic stimulation must occur within 200 milliseconds, consistent with the time-course derived from the Libet experiments.[21]

It should be noted that, despite his findings, Libet himself did not interpret his experiment as evidence of the inefficacy of conscious free will. He points out that although the tendency to press a button may be building up for 500 milliseconds, the conscious will retains a right to veto any action at the last moment.[22]

According to this model, unconscious impulses to perform a volitional act are open to suppression by the conscious efforts of the subject (sometimes referred to as "free won't").

A comparison is made with a golfer, who may swing a club several times before striking the ball. The action simply gets a rubber stamp of approval at the last millisecond. Max Velmans argues however that "free won't" may turn out to need as much neural preparation as "free will" (see below).[23]

The possibility that human "free won't" is also the prerogative of the subconscious is being explored.

As green light switches to yellow, research seems to suggest that humans cannot tell the difference between "deciding" to keep driving, and having no time to decide at all.

Recent research by Simone Kühn and Marcel Brass suggests that our consciousness may not be what causes some actions to be vetoed at the last moment.

First of all, their experiment relies on the simple idea that we ought to know when we consciously cancel an action (i.e. we should have access to that information ).

Secondly, they suggest that access to this information means humans should find it easy to tell, just after completing an action, whether it was impulsive (there no time to decide) and when there was time to deliberate (the participant decided to allow/ not to veto the action).

The study found evidence that subjects could not tell this important difference.

This again leaves some conceptions of free will vulnerable to the Introspection illusion.

The researchers interpret their results to mean that the decision to "veto" an action is determined subconsciously, just as the initiation of the action may have been subconscious in the first place.[24]

It started by gathering participants’ reaction times (RT). In order to collect RT information, volunteers were asked to respond to a go-signal as quickly as possible in primary response trials [24]. These baseline trials were interlaced with experimental trials in which the go-signal would be subsequently followed by either a “stop” or “decide” signal. These occasional second signals appeared with various delays. The occasional decide trials, for example, required that the participants prevent themselves from acting impulsively on the initial go-signal long enough to decide what to do. Due to the varying delays, this was sometimes impossible (e.g. some decide signals simply appeared too late in the movement process to be obeyed, and for the action to stop). Note that any trial where the subject does react, and where it is impulsively, shows a quick RT closer to 600ms. Any trial where they took time to decide should show a comparatively slow RT, in this case closer to 1400ms.[24]

Kuhn and Brass wanted to test participant self-knowledge.

The first step was that after every decide trial, participants were next asked whether they had actually had time to decide.

Specifically, the volunteers were asked to label each decide trial as either failed-to-decide (the action was the result of acting impulsively on the initial go-signal) or successful decide (the result of a deliberated decision). See the diagram on the right for this decide trial split: failed-to-decide and successful decide; the next split in this diagram (participant correct or incorrect) will be explained at the end of this experiment. Note also that the researchers sorted the participants’ successful decide trials into “decide go” and “decide nogo”, but were not concerned with the nogo trials since they did not yield any RT data (and are not featured anywhere in the diagram on the right). Note that successful stop trials did not yield RT data either.

The different types of trials and their different possible outcomes.Kuhn and Brass now knew what to expect: primary response trials, any failed stop trials, and the “failed-to-decide” trials were all instances where the participant obviously acted impulsively – they would show the same quick RT. In contrast, the “successful decide” trials (where the decision was a “go” and the subject moved) should show a slower RT.

Presumably, if deciding whether to veto is a conscious process, volunteers should have no trouble distinguishing impulsivity from instances of true deliberate continuation of a movement.

Again, this is important since decide trials require that participants rely on self knowledge.

Note that stop trials cannot test self knowledge because if the subject does act, it is obvious to them that they reacted impulsively.[24]

The general distribution of reaction times for the different trials. Notice the timing of the two peaks for trials labelled "successful decide".Unsurprisingly, the recorded RTs for the primary response trials, failed stop trials, and “failed-to-decide” trials all showed similar RTs: 600ms seems to indicate an impulsive action made without time to truly deliberate. What the two researchers found next was not as easy to explain: while some “successful decide” trials did show the tell-tale slow RT of deliberation (averaging around 1400ms), participants had also labelled many impulsive actions as “successful decide”. This result is startling because participants should have had no trouble identifying which actions were the results of a conscious “I will not veto”, and which actions were un-deliberated, impulsive reactions to the initial go-signal. As the authors explain:

“ [The results of the experiment] clearly argue against Libet’s assumption that a veto process can be consciously initiated. He used the veto in order to reintroduce the possibility to control the unconsciously initiated actions. But since the subjects are not very accurate in observing when they have [acted impulsively instead of deliberately], the act of vetoing cannot be consciously initiated.[24] ”

In decide trials the participants, it seems, were not able to reliably identify whether they had actually had time to decide – at least, not based on internal signals. The authors explain that this result is difficult to reconcile with the idea of a conscious veto, but simple to understand if the veto is considered an unconscious process.[24] Thus it seems that the intention to move might not only arise from the subconscious, but it may only be inhibited if the subconscious says so. This conclusion would reduce the consciousness to more of narrator than direct arbiter (i.e. unconscious processing causes all thoughts, and these thoughts are again processed subconsciously).

In this recent experiment, subjects could not reliably distinguish between "producing an action without stopping and stopping an action before voluntarily resuming".[24] The conclusions that are drawn from this information, however - such as the assumption that only the faster decisions can be unconscious and that because the conscious ones have the same timing they must also be unconscious -, have yet to be debated properly or even replicated. It is also worth noting that Libet consistently referred to a veto of an action that was initiated endogenously.[22] That is, a veto that occurs in the absence of external cues, instead relying on only internal cues (if any at all). This veto may be a different type of veto than the one explored by Kühn and Brass using their decide signal.

The idea behind retrospective construction is that, while part of the "yes, I did it" feeling of agency seems to occur during action, there also seems to be processing performed after the fact - after the action is performed - to establish the full feeling of agency.[25]

Subconscious agency processing can even alter, in the moment, how we perceive the timing of sensations or actions. [26] [27]

Kühn and Brass apply retrospective construction to explain the two peaks in "successful decide" RT's. They suggest that the late decide trials were actually deliberated, but that the impulsive early decide trials that should have been labelled "failed to decide" were mistaken during subconscious agency processing. They explain that people may "persist in believing that they have access to their own cognitive processes" when in fact we do a great deal of automatic subconscious processing before conscious perception occurs.

Scanning the brain in action, the readiness potential that indicates the beginning of movement genesis is recorded by an EEG applied to the pre-supplementary motor area (pre-SMA) of the brain. Directly stimulating the pre-SMA causes volunteers to report a feeling of intention, and sufficient stimulation of that same area causes physical movement [28].

This suggests that awareness of an intention to move may literally be the “sensation” of the body’s early movement, but certainly NOT the cause.

Other studies have at least suggested that "The greater activation of the SMA, SACC, and parietal areas during and after execution of internally generated actions suggests that an important feature of internal decisions is specific neural processing taking place during and after the corresponding action...Therefore, awareness of intention timing seems to be fully established only after execution of the corresponding action, in agreement with the time course of neural activity observed here." [29].

Notice that a prediction of the future state is made just before the movement occurs.

Presumably that efference copy is used to establish agency.

Neurological disorders such as alien hand syndrome make a person lose his sense of agency.

Our ability to talk to ourself and think in words is a major part of the human experience of consciousness.

From a young age, individuals are encouraged by society to introspect carefully, but also to communicate the results of that introspection [30].

Simon Jones and Charles Fernyhough explain that our ability to talk to ourselves, “inner speech”, is essentially regular speech [31].

This theory originates with the developmental psychologist Lev Vygotsky, who observed that children will often narrate their actions out loud before eventually replacing the habit with the adult equivalent: sub-vocal articulation.

During sub-vocal articulation, no sound is made but the mouth still moves—or at least the brain might prepare the actions without executing them. Jones and Fernyhough explain that hearing words in our head is caused by sub-vocal articulation. This hypothesis has received support from evidence that schizophrenics suffering auditory hallucinations, more specifically auditory verbal hallucinations (AVH), need only to open their mouths in order to disrupt the voices in their heads.

To explain exactly how inner speech works, what goes wrong with AVH patients, and how all the actions we’ve been discussing might work subconsciously, Jones and Fernyhough apply what is known as the forward model of motor control (FMMC), a model that uses the idea of efferent copies.

As the body sends the information required to generate movement, it is as though the same information is faxed to other areas of the brain. This "efferent" copy of planned-movement information is used by the brain to predict what sensations will come next, effectively predicting the upcoming position of a limb, for example. If the actual sensations match the predicted sensations, we experience the feeling of agency. If there is a mismatch between the body and its predicted position, for example due to obstructions or other cognitive disruption, no feeling of agency occurs. The FMMC explains AVH rather easily: since inner speech is a normal action, the malfunction in schizophrenic patients is in the generation of the predictive efferent copy used to confirm and cause the feeling of agency. That is why patients suffering AVH perceive their self talk as alien. It is by the application of the FMMC that we might imagine how other consciousness processes could be the result of efferent, predictive processing. If our conscious self is the efferent copy of actions and vetos being performed, then the consciousness is a sort of narrator of what is already occurring in the body, and an incomplete narrator at that. This model helps explain how we might experience a free will even if it were determined. Only one thing is certain: correlation of a conscious "intention to move" with the actual "action" does not guarantee causation.

How the brain constructs consciousness is still a mystery, and cracking it open would have a significant bearing on the question of free will.

Numerous different models have been proposed, for example, the Multiple Drafts Model which argues that there is no central Cartesian theater where conscious experience would be represented, but rather that consciousness is located all across the brain.

This model would explain the delay between the decision and conscious realization, as experiencing everything as a continuous 'filmstrip' comes behind the actual conscious decision.

On the contrary, few models of Cartesian materialism have gained some recognition by neuroscience, implying that there actually might be special brain areas that store the contents of consciousness.

This does not, however, rule out the possibility of a conscious will.

Other models such as epiphenomenalism argue that conscious will is an illusion, and that consciousness is a by-product of physical states of the world.

Work in this sector is still highly speculative, and there is no single model of consciousness which would be favored by the researchers. See also: Philosophy of mind

[edit] See alsoThought identification, through the use of technology

[edit] References^

Soon, C.; Brass, M.; Heinze, H.; Haynes, J. (2008). "Unconscious determinants of free decisions in the human brain.". Nature neuroscience 11 (5): 543–545. doi:10.1038/nn.2112. PMID 18408715. edit
^ "The Moral Landscape", pg. 112
^ a b c W. R. Klemm (2010). "Free will debates: Simple experiments are not so simple". Advances in Cognitive Psychology. doi:10.2478/v10053-008-0076-2. PMC 2942748. PMID 20859552. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2942748.
^ a b Libet, B., Gleason, C.A., Wright, E.W., Pearl, D.K. (1983). Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain. 106 (3):623–642. PMID 6640273
^ Libet, B. (1985) Unconscious cerebral initiative and the role of conscious will in voluntary action. Behavioral and Brain Sciences, 8: 529–566.
^ Dennett, D. (1991) Consciousness Explained. The Penguin Press. ISBN 0-7139-9037-6 (UK Hardcover edition, 1992) ISBN 0-316-18066-1 (paperback)
^ Dennett, Daniel C and Marcel, Kinsbourne (1992)Time and the Observer. Behavioral and Brain Sciences 15(2), 183–247.
^ a b Haggard, P. and Eimer, M. (1999). On the relation between brain potentials and the awareness of voluntary movements. Experimental Brain Research 126, 128–133. PMID 10333013
^ Trevena, J.A. and Miller, J. (2002). Cortical movement preparation before and after a conscious decision to move. Consciousness and Cognition 11, 162–190. PMID 12191935
^ Haggard, P. (2005). Conscious intention and motor cognition. Trends in Cognitive Sciences 9, 6 : 290–295. PMID 15925808
^ Banks, W. P. and Pockett, S. (2007) Benjamin Libet's work on the neuroscience of free will. In M. Velmans and S. Schneider (eds.) The Blackwell Companion to Consciousness. Blackwell. ISBN 978-1-4051-6000-1 (paperback)
^ Unconscious determinants of free decisions in the human brain, Nature Neuroscience 11, 543 - 545 (2008)
^ http://bigthink.com/ideas/19231
^ Banks, W.P. and Isham, E.A.(2009). We infer rather than perceive the moment we decided to act. Psychological Science, 20, 17-21
^ Judy Trevena, Jeff Miller (2009). "Brain preparation before a voluntary action: Evidence against unconscious movement initiation". Consciousness and Cognition: 447–456. doi:10.1016/j.concog.2009.08.006. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WD0-4X5HY69-1&_user=10&_coverDate=03%2F31%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b94cf1e9e558243bb206397f49445355&searchtype=a.
^ Anil Ananthaswamy (2009). "Free will is not an illusion after all". New Scientist magazine. http://www.newscientist.com/article/dn17835-free-will-is-not-an-illusion-after-all.html.
^ Haggard, P. (2008). Human volition: towards a neuroscience of will. Nature Reviews Neuroscience , 9, 934-946
^ a b c Matsuhashi, M., & Hallett, M. (2008). The timing of the conscious intention to move. European Journal of Neuroscience , 28, 2344-2351.
^ Alfred R. Mele (2008). John Baer, James C. Kaufman & Roy F. Baumeister. ed. "Psychology and free will: A commentary". Are we free? Psychology and free will (New York: Oxford University Press): 325–346. ISBN 9780195189636. http://books.google.com/books?id=6DrNDONGuAQC&pg=PA12&dq=re+we+free%3F+Psychology+and+free+will&hl=en&ei=InAaTLShC5W4NbP2wKEF&sa=X&oi=book_result&ct=result&resnum=1&ved=0CDEQ6AEwAA#v=onepage&q=mele&f=false.
^ Ammon, K. and Gandevia, S.C. (1990) Transcranial magnetic stimulation can influence the selection of motor programmes. Journal of Neurology, Neurosurgery and Psychiatry 53: 705–707. PMID 2213050
^ Brasil-Neto, J.P., Pascual-Leone, A., Valls-Solé, J., Cohen, L.G. and Hallett, M. (1992) Focal transcranial magnetic stimulation and response bias in a forced-choice task. Journal of Neurology, Neurosurgery and Psychiatry 55: 964–966. PMID 1431962
^ a b Libet, (2003). "Can Conscious Experience affect brain Activity?", Journal of Consciousness Studies 10, nr. 12, pp 24–28.
^ Velmans, M.Preconscious free will, Journal of Consciousness Studies 10, nr. 12, pp 42–61.(2003)
^ a b c d e f g Kühn, S., & Brass, M. (2009). Retrospective construction of the judgment of free choice. Consciousness and Cognition, 18, 12-21.
^ Wegner, D. M. (2003). The mind’s best trick: how we experience conscious will. TRENDS in Cognitive Sciences , 7 (2), 65-69.
^ Lau, H. C., Rogers, R. D., & Passingham E, R. (2007). Manipulating the Experienced Onset of Intention after Action Execution. Journal of Cognitive Neuroscience , 19 (1), 81-90.
^ Haggard, P. (2008). Human volition: towards a neuroscience of will. Nature Reviews Neuroscience , 9, 934-946.
^ Haggard, P. (2008). Human volition: towards a neuroscience of will. Nature Reviews Neuroscience, 9, 934-946.
^ Guggisberg, A. G., Dalal, S. S., Findlay, A. M., & Nagarajan, S. S. (2008). High-frequency oscillations in distributed neural networks reveal the dynamics of human decision making. Frontiers in Human Neuroscience , 1, 1-14.
^ Schlinger, H. D. (2009). Some clarifications on the role of inner speech in consciousness. Consciousness and Cognition (18), 530-531.
^ Jones, S. R., & Fernyhoug, C. (2007). Thought as action: Inner speech, self-monitoring, and auditory verbal hallucinations. Consciousness and Cognition , 16, 391-399.
Retrieved from "http://en.wikipedia.org/wiki/Neuroscience_of_free_will"