Category Archives: Psychology

Man in Vegetative State Shows Brain Activity to Movie: What Does It Mean?

In a recent study, Naci et al. investigated how the brain responds to an 8 minute Alfred Hitchcock movie. In healthy subjects they found that frontal and parietal areas indicative of executive functioning were active during the most suspenseful parts of the movie. Then they showed the same movie to two patients diagnosed as being in a vegetative state, one of which who had been in VS for 16 years. In one of the patients they found that “activity in a network of frontal and parietal regions that are known to support executive processing significantly synchronized to that of healthy participants”. In other words, the vegetative man’s brain “tracked” the suspense-points of the movie in the same way that healthy controls did. They reasoned that the patient was therefore consciously aware of the video, despite being behaviorally unresponsive:

The patient’s brain activity in frontal and parietal regions was tightly synchronized with the healthy participants’ over time, and, crucially, it reflected the executive demands of specific events in the movie, as measured both qualitatively and quantitatively in healthy individuals. This suggested that the patient had a conscious cognitive experience highly similar to that of each and every healthy participant, while watching the same movie.

But what’s the connection between executive functioning and conscious experience? The authors write:

The “executive” function of the brain refers to those processes that coordinate and schedule a host of other more basic cognitive operations, such as monitoring and analyzing information from the environment and integrating it with internally generated goals, as well as planning and adapting new behavioral schemas to take account of this information. As such, executive function is integral to our conscious experience of the world as prior knowledge is integrated into the current “state of play” to make predictions about likely future events.

Does this mean that executive functioning is always conscious? Is the unconscious brain incapable of “monitoring and analyzing information from the environment” and “integrating” that information with goals? Color me skeptical but I believe in the power of the unconscious mind to perform these functions without the input of conscious awareness.

Several examples come to mind. In the “long-distance truck driver” phenomenon people can drive automobiles for minutes if not hours without the input of conscious awareness. Surely driving requires “monitoring and analyzing information from the environment” in addition to integrating with goals and adapting new behaviors to deal with novel road conditions.

Another example is automatic writing, where people can write whole intelligent paragraphs without the input of conscious attention and the “voice” of the writing is distinct from that of the person’s normal personality, channeling the personalities of deceased persons or famous literary people. People would hold conversations with their automatic writing indicating that the unconscious writer was responding to the environment and surely “monitoring and analyzing information”. Im not aware of any brain imaging studies of automatic writing but I would not be surprised if frontal and parietal regions were active given the complexity of handwriting as a cognitive task. Same with long-distance truck driving.

My point is simply to raise the question: Can executive function happen unconsciously? Naci et al. say that executive function is “integral” to conscious experience. That might be true. But is conscious experience integral to executive functioning? Maybe not. There is a litany of complex behaviors that can be performed unconsciously, all of which likely recruit frontal and parietal networks of the brain. We can’t simply assume that just because information integration occurred that conscious awareness was involved. To make that inference would require us to think that the unconscious mind is “dumb” and incapable of integrating information. But there is plenty of reason to think that what Timothy Wilson calls the “adaptive unconscious” is highly intelligent and capable of many “higher-order” cognitive functions including monitoring, integrating, planning, reasoning, etc.


Filed under Consciousness, Psychology

Can the Clinical Diagnosis of Disorders of Consciousness Avoid Behaviorism?


The “standard approach” in clinical neurology has been accused of suffering from an implicit “behaviorist epistemology” because disorders of consciousness are typically diagnosed on the basis of a lack of behavior. All the gold standard diagnostic assessment programs such as the JFK-Coma Recovery Scale are behavioral in nature insofar as they are expressly looking for behavior or the lack of behavior, either motor behavior or verbal behavior. If the behavior occurs appropriately in response to the command or stimulus then they get points that accumulate towards “normal” consciousness. If no behavior is observable in response to the cue then they don’t get points and are said to have a “disorder of consciousness”.

The problem with this approach is both conceptual and empirical. Conceptually, there is no necessary link between behavior and consciousness because unless you are Gilbert Ryle or Wittgenstein you don’t want to define consciousness in terms of behavior. That is, we don’t want to define “pain” as simply the behavior of your limbs whenever your cells are damaged, or the disposition to say “ouch”. The reason we don’t want to do this is because pain is supposed to be a feeling, painfulness, not a behavior.

Empirically, we know of many cases where behavior and consciousness can be decoupled such as in the total locked-in state where someone’s mind is more-or-less normal but they are completely paralyzed, looking for all intents and purposes like someone in a deep coma or vegetative state yet retaining normal brain function. From the outside they would fail these behavioral assessment techniques yet from the inside have full consciousness. Furthermore we know that in some cases of general anesthesia there can be a complete lack of motor response to stimulation while the person maintains their conscious awareness.

Another problem with the behaviorist epistemology of clinical diagnosis is that the standard assessment scales require a certain level of human expertise in making the diagnostic judgment. Although for most scales there is high inter-rater reliability it nevertheless ultimately comes down to a fallible human making a judgment about someone’s consciousness on the basis of subtle differences between “random” and “meaningful” behavior. A random behavior is just that: a random, reflexive movement that signifies no higher purpose or goal. But if I ask someone to squeeze my hand and they squeeze it, this is a meaningful sign because it suggests that they can listen to language and translate a verbal command to a willed response. But what if the verbal command to squeeze just triggers an unconscious response to squeeze? Sure, it’s possible. No one should rule it out. But what if they do it 5 times in a row? Or what if I say “don’t squeeze my hand” and they don’t squeeze it? Now we are getting into what clinicians call “unambiguous signs of consciousness” because the behavior is expressive of a meaningful purpose and shows what they call “contingency”, which is just another way of saying “appropriate”.

But what does it mean for a behavior to really be meaningful? Just that there is a goal-structure behind it? Or that it is willed? Again, we don’t want to define “meaning” or “appropriateness” in terms of outward behavior because when you are sleepwalking your behavior is goal-structured yet you are not conscious. Or consider the case of automatic writing. In automatic writing one of your hands is capable of having a written conversation and writing meaningful linguistic statements without “you” being in control at all. So clearly there is a possible dissociation between “meaningful” behavior and consciousness. All we can say is that for normal people in normal circumstances meaningful behavior is a good indicator of normal consciousness. But notice how vacuous that statement is. It tells us nothing about the hard cases. 

So in a nutshell the diagnosis of disorders of consciousness has an inescapable element of human subjectivity in it. Which is precisely why researchers are trying to move to brain-based diagnostic tools such as fMRI or EEG, which are supposed to be more “objective” because they skip right over the question of meaningful behavior and look at the “source” of the behavior: the brain itself. But I want to argue such measures can never bypass the subjectivity of diagnosis without going full behaviorist. The reason why brain-based measures of disorders of consciousness are behaviorist is simply because you are looking at the behavior of neurons. You can’t see the “feelings” of neurons from a brain scanner anymore than you can see the “feeling” of pain from watching someone’s limb move. Looking at the brain does not grant you special powers to see consciousness more directly. It is still an indirect measure of consciousness and it will always require the human judgment of the clinician to say “Ok, this brain activity is going to count as a measure towards “normal” consciousness”. It might be slightly more objective but it will never be any less subjective unless you want to define normal consciousness in terms of neural behavior. But how is that any different from standard behaviorism? The only difference is that we are relying on the assumption that neural behavior is the substrate of consciousness. This might be true from a metaphysical perspective. But it’s no help in the epistemology of diagnosis because as an outside observer you don’t see the consciousness. You just see the squishy brain or some representation on a computer screen. I believe there is a circularity here that cannot be escaped but I won’t go into it here (I talk about it in this post).


Filed under Consciousness, Philosophy of science, Psychology, Uncategorized

More Evidence for Vestigial Bicamerality

Acclaimed cultural anthropologist Tanya Luhrmann has a new paper out in the British Journal of Psychiatry: “Differences in voice-hearing experiences of people with psychosis in the USA, India and Ghana: interview-based study“.

The paper further corroborates the theoretical framework of Julian Jaynes and his idea of bicamerality. The bicameral paradigm is quintessentially a hallucinatory voice guiding or command you to do everyday tasks. Consider this summary of the interviews from patients in Chennai, India

These voices behaved as relatives do: they gave guidance, but they also scolded. They often gave commands to do domestic tasks. Although people did not always like them, they spoke about them as relationships. One man explained, ‘They talk as if elder people advising younger people’. A woman heard seven or eight of her female relatives scold her constantly. They told her that she should die; but they also told her to bathe, to shop, and to go into the kitchen and prepare food.

Now consider Jaynes’ hypothetical description of the Egyptian concept of “ka” or “spirit double”:

It is obvious from the preceding chapters that the ka requires a reinterpretation as a bicameral voice. It is, I believe, what the ili or personal god was in Mesopotamia. A man’s ka was his articulate directing voice which he heard inwardly, perhaps in a parental or authoritative accents, but which when heard by his friends or relatives even after his own death, was, of course, hallucinated as his own voice…

The ka of the god-king is of particular interest. It was heard, I suggest, by the king in the accents of his own father…

[In early civilizations]…each person had a part of his nervous system which was divine, by which he was ordered about like any slave, a voice or voices which indeed were what we call volition and empowered what they commanded and were related to the hallucinated voices of others in a carefully established hierarchy.

Going back to the Luhrmann interviews, we can see the essential social-hierarchical component of bicamerality still at work today in voice-hearers:

They made comments that suggested that these voices were both social relationships and entertainment: ‘I like my mother’s voice’; later, this woman added ‘I have a companion to talk [to] . . . [laughs] I need not go out to speak. I can talk within myself!’

Jaynes’ other suggestion about bicamerality is that the voices served a behavioral function: they weren’t just echoes of a broken nervous system, but were a way for the human nervous system to guide itself adaptively. They are a channel for what Jaynes called “stored-up admonitory wisdom”. Luhrmann cites one man as saying ‘[the voices] just tell me to do the right thing. If I hadn’t had these voices I would have been dead long ago.”

Now imagine an entire city where the majority of people are voice-hearers and there is an elaborate cultural mythology for interpreting the voices as “personal gods”, where hearing divine or special voices talk to you is perfectly normal in every way. Can you imagine it? Jaynes could. But it stretches the imagination. But that’s no reason to think it wasn’t the case. Just because modern people with modern minds not hearing voices find that situation “psychotic” or “crazy” doesn’t mean that bicamerality has always been limited to 1-2% of the population. It was likely spread throughout the population in much greater proportion than it is today. It is in fact part of the human gene pool, which is why schizophrenia today has such a large genetic component. Complicated cognitive mechanisms such as voice hearing don’t just stay in the gene pool for no reason. It suggests that it was adaptive in the not too distant past. And for some people in some cultures, as Luhrmann indicates, it still serves an adaptive function. John Geiger’s book The Third Man Factor also talks about the adaptive function of vestigial bicamerality in the context of extreme survival, where people on the verge of life and death have been guided to safety by following the instructions of hallucinated voices.



Filed under Consciousness, Psychology

Vegetative State Patients as Moral Patients


Adrian Owen (2006) recently discovered that some vegetative state (VS) patients have residual levels of cognition, enabling them to communicate using brain scanners. This discovery is clearly morally significant but the problem comes from specifying why exactly the discovery is morally significant and whether extant theories of moral patienthood can be applied to explain the significance. In this paper I explore Mark Bernstein’s theory of experientialism, which says an entity deserves moral consideration if they are a subject of conscious experience. Because VS is a disorder of consciousness it should be straightforward to apply Bernstein’s theory to Owen’s discovery but several problems arise. First, Bernstein’s theory is beset by ambiguity in several key respects that makes it difficult to apply to the discovery. Second, Bernstein’s theory of experientialism fails to fully account for the normative significance of what I call “narrative experience”. A deeper appreciation of narrative experience is needed to account for the normative significance of Owen’s findings.



This paper has gone through so many drafts. I swear I’ve rewritten it 5 times from more or less scratch. Each time I’ve tried to narrow my thesis to be ever smaller and less ambitious because I’m pretty sure that’s the only way I’m going to get this thing passed by my qualifying paper committee. As always, any thoughts or comments appreciated.

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Quote for the Day – The Dangers of Anthropomorphism

It may seem a benign slip from sad eyes to depression, but anthropomorphisms often slide from benign to harmful. Some risk the welfare of the animals under consideration. If we’re to put a dog on antidepressants based on our interpretation of his eyes, we had better be pretty sure of our interpretation. When we assume we know what is best for an animal, extrapolating from what is best for us or any person, we may inadvertently be acting at cross-purposes with our aims. For instance, in the last few years there has been considerable to-do made about improved welfare for animals raised for food, such as broiler chickens who have access to the outside, or have room to roam in their pens. Though the end result is the same for the chicken — it winds up as someone’s dinner — there is a budding interest in the welfare of the animals before they are killed.

But do they want to range freely? Conventional wisdom holds that no one, human or not, likes to be pressed up against others. Anecdotes seem to confirm this: given the choice of a subway car jammed with hot, stressed commuters, and one with only a handful of people, we choose the latter in a second (heeding the possibility, of course, that there’s some other explanation – a particularly smell person, or a glitch in air-conditioning – that explains this favorable distribution). But the natural behavior of chickens may indicate otherwise: chickens flock. They don’t sally forth on their own.

Biologists devised a simple experiment to test the chickens’ preferences of where to be: they picked up individual animals, relocated them randomly within their houses, and monitored what the chickens did next. What they found was that most chickens moved closer to other chickens, not farther away, even when there was open space available. Given the option of space to spread their wings…they choose the jammed subway car.

This is not to say that chickens thus like being smushed against other birds in a cage, or find it a perfectly agreeable life. It is inhumane to pen chickens so tightly they cannot move. But it is to say that assuming resemblance between chicken preferences and our preferences is not the way to insight about what the chicken actually does like. Not coincidentally, these broiler chickens are killed before they reach six weeks of age; domestic chicks are still being brooded by their mothers at that age. Deprived of the ability to run under her wings, the broiler chickens run closer to other chickens.

~Alexandra Horowitz, Inside of a Dog: What Dogs See, Smell, and Knowp. 16-17

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May 22, 2014 · 9:26 am

Correcting Misinterpretations of Julian Jaynes’ Theory – Bernard Baars edition

In one of only three posts at his seemingly defunct blog Your Conscious Brain, neuroscientist Bernard Baars writes:

A few decades ago the Princeton psychologist Julian Jaynes speculated that consciousness is a recent phenomenon – just a few thousand years old. Jaynes thought so based on a difference between the language of Homer’s Illiad and the Odyssey. In the Odyssey, he claimed, the voices of the gods are perceived to come from the outside world. In the Illiad, on the other hand, the gods are thought to speak inside of the heroes’ heads.

But fully formed language is now believed to date back some 50,000 to 100,000 years, and as for consciousness, at least sensory consciousness seems to be much, much more ancient. Hemispheric lateralization such as we find in language can be observed in guinea pigs and song birds. The hoped-for “language gene” of FOXP2 is known to exist in alligators. Human cognitive faculties are spun off from much more ancient adaptations

There are several misleading things going on here.

First, Baars engages in the classic bait-and-switch move by attacking Jaynes for a view he never held. Jaynes would totally agree that “sensory consciousness” is an ancient phenomenon shared with animals – that’s why he was so careful to distinguish perception and cognition generally from what he thought of as “consciousness” – a short-hand term for what philosophers would call “reflective self-consciousness”.

Later Baars admits “That is not to say that tree shrews have ‘higher level consciousness’ (Edelman, 1989), which is heavily dependent on language, executive and social functions, the brain bases of human culture.” But that type of “higher level consciousness” is exactly what Jaynes claimed to be a recent development based on language! So why would Baars start off saying Jaynes thought “consciousness” is a recent development when in the context of Baar’s own vocabulary he should have said “Jaynes speculated that higher-order consciousness is a recent phenomenon”? Even a cursory inspection of Jaynes’ book would show that it’s no refutation of his theory to point out that sensory awareness is ancient and shared with animals – this falls under the general umbrella of what Jaynes’ called “perceptual reactivity”.

Why do people bring up Jaynes only in brief, stereotyped snippets only to immediately dismiss the theory as preposterous? I don’t know. I suspect it’s because people never bothered to read the 1990 edition that has an “afterword” where Jaynes complains about the obstacles he’s had in getting academics to give him a fair reading. Or I suspect they never read the book at all – or read it so long ago that they only remember a distorted version like a bad translation at the end of the children’s game “telephone”.

Second, Baars implies that Jaynes’ only line of evidence for his view is the differences between the Iliad and the Odyssey. This is misleading. The transition in writing style from the Iliad to the Odyssey represents a shift in cognitive ability that is typical in different ancient literature as well, including the Old Testament (compare the oldest book, Amos, to the latest books, like Song of Solomon). Also, Jaynes’ evidence base included reports in cultural anthropology.

Baars also writes that  “fully formed language is now believed to date back some 50,000 to 100,000 years” as if this is supposed to be a crucial blow to Jaynes’ view. As Jaynes writes in his 1990 afterword,

A weak form of the theory would state that, yes, consciousness is based on language, but instead of its being so recent, it began back at the beginning of language, perhaps even before civilization…

The exact dates don’t matter – Jaynes was always flexible on this point, knowing that new archeological finds could overturn the precise dates he hypothesized. But the general point is that if you’re a social constructivist about higher-order consciousness, then it doesn’t matter if the type of language necessary to support it is 12k years old or 50k years old. The point is that it’s not millions of years old and shared by non-linguistic animals. That’s what is interesting about Jaynes’ theory.

I’ll end with another remark from Jaynes’ 1990 afterword that was prescient indeed:

A favorite practice of some professional intellectuals when at first faced with a theory as large as the one I have presented is to search for that loose thread which, when pulled, will unravel all the rest. And rightly so. It is a part of the discipline of scientific thinking. In any work covering so much of the terrain of human nature and history, hustling into territories jealously guarded by myriad aggressive specialists, there are bound to be such errances, sometimes of fact but I fear more often of tone. But that the knitting of this book is such that a tug on such a bad stitch will unravel all the rest is more of a hope on the part of the orthodox than a fact in the scientific pursuit of truth. The book is not a single hypothesis.

EDIT: Apparently this is the 500th post on this blog. Cool.

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A Brief History of the Vegetative State


1.0 Introduction
Vegetative state syndrome (VS) is a rare but extremely devastating neurological disorder resulting from severe brain damage. The increasing sophistication of critical neural care has made it possible for people to be kept alive with only the barest of brain function; machines can now take over the control and regulation of basic organic functions. An estimated 13,000-44,000 Americans are currently in a vegetative state. The causes of VS are diverse ranging from traumatic brain damage such as from car accidents to hypoxia from drowning, stroke, heart attack, or drug overdoses. VS is considered a disorder of consciousness insofar as it is assumed to deeply affect conscious awareness. Hence, VS is widely described as “wakefulness without awareness” or “wakeful unawareness” (Jennet & Plum, 1972).

When most laypersons hear about VS they think about so called “persistent vegetative state” which is a term used to describe VS patients 1 month after acute injury. Persistent VS is often confused with permanent VS which is defined by the Multi-Society Task Force as a VS state 3 months after a non-traumatic brain injury and 12 months after traumatic injury. VS is often confused with brain death, which is the complete and irreversible cessation of neurological function. VS is also distinct from being in a coma, a term that comes from the ancient Greek term “koma”, meaning “deep sleep” (Fig. 1). Coma is operationally defined in terms of a complete lack of overt response to vigorous stimulation and attempts to arouse the patient. Plum and Posner define the state of coma as being

unarousable, unaware of all elements in the environment, with no spontaneous interaction or awareness of the interviewer, so that the interview is difficult or impossible even with maximum prodding (2007, p. 184).

Coma patients are still breathing and their basic physiological systems are still functioning but their eyes never open and they appear to be in a deep sleep marked by a presumed total lack of consciousness. If a patient recovers from a coma at all, they typically begin to recover after a week or two, transitioning through progressive stages starting with vegetative state and ideally moving through a continuum of minimally conscious states to either locked-in syndrome, or a full cognitive recovery.


Fig. 1 From (Posner, 2008).

2.0 Ancient to Modern Conceptions of the Vegetative State
The concept of VS can be indirectly traced by to Ancient Greece and the Hippocratic school of medicine (400-200 BCE), sometimes called the “Coan school” because it was apparently located on the island of Cos in the Aegean Sea. Some scholars believe that the Hippocratic school was an ancient Pythagerean-like cult that had a quasi-religious and mystical set of beliefs and initiation rights. In Ancient Greek medicine one of the terms closest to referring to what is now called the vegetative is the condition called “apoplexy”, referred to stroke or brain hemorrhage, meaning “being struck by violence”. Due to the complete lack of knowledge of how brain damage affected cognitive function, the ancient Greeks lumped many more neurological conditions under the same category than we would do now. Consider the following Hippocratic description of apoplexy

The healthy subject is taken with sudden pain; he immediately loses his speech and rattles his throat. His mouth gapes and if one calls him or stirs im he only groans but understands nothing. He urinates copiously without being aware of it. If ever does not supervene, he succumbs in seven days, but if it does he usually recovers (Clarke, 1963, p. 307)

Besides the Hippocratic writings, the most comprehensive source of Ancient knowledge about apoplexy comes from the works of Galen written between 200-150 BCE.Although Galen’s writings on apoplexy were fragmented and scattered through his corpus, his writings on the subject constitute the first medical taxonomy of the condition. According to Galen, “Apoplexy [is] a palsy of the whole body, accompanied by impairment of its leading functions” (Quoted in Karenberg, 1994, p. 87).

Since Galen, little progress in diagnosing, understanding or treating apoplexy was made in between ancient Greece and the the beginning of the Enlightenment and the birth of modern, mechanistic approaches to medicine such as William Harvey’s hydraulic model of the circulatory system. Much of this lack of progress can be chalked up to the collapse of the Roman empire, the rise of the institutions of the Church and numerous other complex social, economic, and political factors. The scholastic and highly conservative nature of medicine essentially kept the Hippocratic conception of apoplexy intact all the way up through the 17th century. For example, when we read 17 century doctor Thomas Willis’ description of apoplexy, it’s quite apparent that 17th century medicine had made little progress in the description of these complex and tragic neurological conditions. According to Willis,

The Apoplexy, according to the import of the Word, denotes a striking, and by reason of the stupendous Nature of the affect, as tho it contain’d somewhat Divine, it is called a sideration: for those that are seized with it, as tho they were Planet-struck, or smitten by an invisible Deity, fall on the Ground on a sudden, and being deprived of Sense and Motion, and the whole animal function (unless that they breath) ceasing, they lye dead as it were for some time, and sometimes dye out-right: and if they revive again, they are oftentimes affected with a general Palsie or an Hemiplegia. (quoted in Storey, C.E., 2007)

For the most part all these doctors could do is either watch the patient die or rely on the spontaneous healing powers intrinsic to the brain itself. During the Middle Ages brain damage was by necessity diagnosed on the basis of easily observable features and thus the typical neurological examination was rudimentary in nature, consisting largely on the basis of: “inspection, palpation of the pulse, and urinoscopy” (Walker, 1998, p. 157).

Until the 19th and 20th centuries, only sparse and intermittent advancement was made in the diagnostic categorization of disorders of consciousness owing to neurological damage. To give some representative examples of the slow terminological evolution, in the 17th century Thomas Willis used the term “coma” in his 1672 work De anima brutorum. In 1679 in Geneva Switzerland Theophile Bonet published Sepulchretum sive Anatomia Practica, a huge compendium of autopsy reports, 70 of which were cases of apoplexy. In the 18th century the Dutch botanist and physician Herman Boerhaave’s described the term “coma” in his lectures as follows:

It is the perfect image of a very profound sleep, like in healthy persons, due to exercise or fuddle. Therefore, there is little distinction, unless by duration. (quoted in Koehler, 2008)

Also of note, in 1898 Oppenheim distinguished between dazedness, somnolence, sopor and coma, which was one of the first modern taxonomies that systematically distinguished between different “levels” of consciousness.As we can see then, between the Middle Ages and the 20th century there was not a great deal of progress made in either diagnosing or treating apoplexy and the state of the field remained largely stagnant.

3.0 Contemporary Approaches to the Vegetative State

The modern history of the vegetative state begins with advances in EMT rescue and technology for sustaining bodily viability in the absence of normal brain function. The artificial respirator was invented in the 1950s by Bjorn Ibsen, a Dutch anesthesiologist who founded the first Intensive Care Unit. Since then, medical advances in artificial nutrition and hydration (ANH) enabled vegetative patients to live decades after the onset of brain damage without higher brain brain or evidence of awareness. The longest known case of VS is Elaine Esposito who was in a VS state for thirty-seven years. Surveys show that people perceive that living decades in this condition or ones similar to it would be a fate “worse than death” (Jennett, 1976) and most people including doctors would prefer to not be kept alive. Most patients deemed not to have a life worth living have ANH withdrawn, which is thought to release endogenous opioids and eventually lead to confusion and then coma from metabolic dysfunction.

Bryan Jennett, a British neurosurgeon and Fred Plum, an American neurologist, coined the term “persistent vegetative state” in a landmark paper published in Lancet in 1972 on April Fools Day. The paper was subtitled “A syndrome in search of a name”. The subtitle “in search of a name” is a reference to the fact that many similar descriptions of vegetative state were available at the time but none of them were broad enough to capture the vegetative state as a syndrome. For example, “Neocortical necrosis” is a term that was applied to a subset of vegetative patients but all such terminology was eventually replaced by terms that didn’t imply any particular causal etiology because of the heterogeneous causes that lead to behavioral unresponsiveness.

Extant medical vocabulary circling around at the time include the French term “coma vigil” Cairns’ term “akinetic mutism” in 1941 to describe a patient with “silent immobility”, German psychiatrist Kretschmer’s term “apallic syndrome”, Stritch (1956) discussions of “severe traumatic dementia”, Arnaud’s term “pie vegetative” in 1963, and Finnish neurosurgeon Vapalahti and Troupp’s “vegetative survival” in 1971. Most of these terms were never universally adopted for the same reason: they were over-specific with respect to the neurological damage or behavioral sequelae. Hence, because Jennett and Plum’s original vegetative syndrome was operationally defined only by a lack of behavioral responsiveness rather than any specific neurological deficit, the term started to enter the general medical lexicon and eventually made it’s way (controversially) into the public sphere due to many high-profile legal cases. Accordingly, Jennett and Plum were not the first to use the phrase “vegetative” nor were they the first to notice and describe the syndrome, but the name they chose stuck and has been in use ever since (though there is now efforts to rename the syndrome; see below). Fred Plum went on to write an influential textbook in the field with Jerome Posner called Diagnosis of Stupor and Coma, which is still in use and currently in its 4th edition (Posner et al., 2008)

The usage of the word “vegetative” to describe people with severe brain damage has always been controversial amongst the general public. One possible reaction to the term is to see it as violating the dignity of the patients by comparing their mental life to that of vegetables. But in the defense of Jennett and Plum, when they first coined “vegetative state”, they referenced the Oxford English Dictionary’s definition of the verb “vegetate”, meaning “To live a merely physical life devoid of intellectual activity or social intercourse”. This usage of the term “vegetate” can be traced back to Ancient Greece e.g. Aristotle’s talked about a “vegetative soul” that was present in all living things including humans. In this respect the term “vegetative” was always meant to be a purely descriptive term for the mental capacity of the patients but it’s hard for laypersons not to read into the term some kind of pejorative connotation.

3.1 Assessment Scales

The history of diagnosing VS and related disorders of consciousness goes hand in hand with the development of behavioral assessment scales and recovery scales. One of the original assessment scales–still in use today–is the Glasgow Coma Scale (GCS) developed by Jennett and Teasdale (1974). The GCS involves 3 dimensions (eyes, verbal, and motor). The eye dimension is graded on a 4-point scale, verbal on a 5 point scale, and motor on a 6 point scale. Thus, the highest possible score is 15 indicating normal consciousness and 3 the lowest, indicating coma or brain death. On the recovery side of things, the Glasgow Outcome Scale was proposed by Jennett and Bond (1975) and describes 5 levels of brain function ranging from coma to VS to severe, moderate, and low cognitive disability. In terms of diagnosis, the JFK Coma Recovery Scale-Revised is currently the gold standard and best validated assessment protocol for diagnosing vegetative patients (Giacino et al., 2004). It involves 6 subscales including auditory, motor, verbal, and visual components. The test is designed to use only observable responses to bedside commands and tests, which allows the test to be used cheaply so long as performed in the hands of trained experts.

3.2 Minimally Conscious State

Today the diagnosis of vegetative state has become more complex and multifaceted in order to recognize the greater heterogeneity and range of cognitive abilities of people diagnosed with the blanket term “vegetative”. Recognizing the need for a more nuanced diagnosis to distinguish patients who are largely vegetative but show intermittent and non-repeatable signs of consciousness, the term “minimally responsible state” (MRS) was introduced by the American Congress of Rehabilitation in 1995. The difference between this and coma or PVS was that MRS required the observation of something “unequivocally meaningful” to the examiner. Later, a group known as the Aspen Workgroup recommended MRS be replaced by “minimally conscious state” (MCS) to emphasize that behavioral responsiveness can occur without consciousness. An estimated 100,000 to 280,000 cases of MCS are thought to exist in the US. The current consensus is that Giacino’s (2002) diagnostic criteria is the gold standard for assessing MCS. Giacino’s definition involves 4 levels of “non-reflexive” behavior:

  • Following simple commands,
  • Gestural or verbal yes/no responses (regardless of accuracy,
  • Purposeful behavior such as those that are contingent due to appropriate environmental stimuli and are not reflexive.
  • Intelligible verbalization.

Any demonstration of these abilities warrants the diagnosis of MCS instead of VS. Currently, these assessment scales like an overarching theoretical basis and without an accepted theory of consciousness it’s unclear whether consciousness is necessary for command following or purposeful behavior, especially given the many apparent counter-examples in clinical neuroscience such as blindsight (c.f. Levy, 2009).

3.3 Famous cases

The modern history of the vegetative state cannot be told without reference to the famous legal cases that were crucial in spurning interest and research on the condition from neurologists, ethicists, and the public at large. These cases operated as catalysts for more precise diagnostic criteria as well as standardization of assessment scales that can be implemented objectively by independent hospitals.

Karen Quinley

Karen Quinley’s case is famous for its association with the right-to-die movement. Karen Quinley was 21 in 1975 when she was found unconscious after an overdose of drugs and alcohol with her friends. After 5 months on a respirator Karen was still in a vegetative state and being cared for in the intensive unit. Karen’s parents, the Quinlans, requested that her respirator be removed because it was deemed by the Catholic church an “extraordinary” medical intervention and thus its removal would not constitute euthanasia, a procedure prohibited by the Catholic doctrine. However, Karen’s neurologist objected to removing the respirator, arguing this would be tantamount to killing her. Eventually the case went to the Supreme Court of New Jersey and the judges decided that the duty to protect life was overridden by the dim prognosis of future awareness. After Karen’s respirator was removed she was still on artificial nutrition and remained alive for another ten years.

Terri Schiavo

On February 25, 1990 Teresa “Terri” Schiavo (age 26) suffered a heart attack and lapsed into a coma. After two months with no signs of recovery, Schiavo was diagnosed with vegetative state disorder (VS). After several years and no signs of recovery, her husband asked to remove her feeding tube. Schiavo’s family objected, arguing that she showed intermittent signs of awareness. Subsequent legal battles involved 14 appeals and widespread media coverage but fifteen years after Schiavo’s heart attack a judge finally ordered her feeding tube to be removed and she died three days later on March 31, 2005.

When Schiavo was diagnosed, VS had not yet been widely distinguished from what is now called the minimally conscious state (MCS), a once controversial diagnosis. MCS patients are similar to VS patients but intermittently show clear signs of consciousness such as purposive behavior but these signs often cannot be reproduced. Once MCS became an established diagnosis (Giacino, 2004), Schiavo’s family later argued in court that she was in a MCS not VS and several doctors testified to this effect. Nevertheless, the judge ruled that Schiavo was in a VS state and that her condition was irreversible.

4.0 21st Century Approaches to the Vegetative State

Investigation into VS and related disorders has exploded in the 21st century. One of the biggest developments in the field came when Adrian Owen and his team published a paper in 2006 in Science claiming to have detected residual levels of consciousness in a patient clinically diagnosed with VS. This discovery sparked intense debate about the methodology and philosophical assumptions of the study but skeptics were finally answered in 2010 when Monti (2010) did a follow-up replication with 50+ subjects. In Monti’s study they found 3 patients in the vegetative state who were capable of “willful modulation” using Owen’s mental imagery paradigm. More recently, a 2014 study published in The Lancet found at least 13 cases of residual cognitive function in patients otherwise diagnosed with vegetative state disorder

4.1 Unresponsive wakefulness syndrome

Unresponsive Wakefulness Syndrome (UWS) is a new term for VS (Laureys et al., 2010; Laureys & Boly, 2012) that is more respectful of patient dignity as well as more diagnostically accurate. Although the term “vegetative” is accurate as a medical generalization across a population of patients, the problem comes when clinicians diagnose a particular person.It’s one thing to talk about vegetative patients in the abstract but if a doctor described your loved one as “vegetative” it would be hard not to find this an frightening, alien label. Despite its pretension to be a merely descriptive term, “vegetative” has negative connotations of a life not worth living, of being “vegged out”.

Furthermore, because modern neuroimaging techniques can now detect residual cognitive function that escapes bedside assessment, it is hasty to infer a patient lacks all cognitive function until they have been systematically tested using the latest technology. The term “vegetative” is inaccurate as a blanket diagnostic label because it ignores the possibility that they will find residual cognitive function using neuroimaging and other techniques that go beyond bedside behavior. The term “unresponsive” is therefore more appropriate than “unaware” and encourages clinicians to not use a single, monolithic state to describe what is in reality a complex continuum. Even though VS is a purely behavioral diagnosis and by itself strictly entails nothing about the presence or absence of consciousness, it’s hard even for clinicians to not adopt a “clinical nihilism” towards these patients despite the very real possibility of these patients having residual cognitive function that – if expressed – would change the diagnosis. However, it’s crucial to realize that there is no logical or empirical basis for inferring the absence of awareness from the absence of a behavioral response, especially since we know through retrospective report that locked-in patients who emerged from total lock-in syndrome were often thirsty, in pain, and aware of nurses and doctors talking around them but completely unable to move any muscles. We also know from retrospective reports of patients under general anesthesia that approximately 1-2 per 1000 cases report some degree of awareness during anesthesia even though they showed no overt motor response detected by the surgeons (Sebel, 2004).

There are many reasons why someone’s awareness would not be detected by a clinical test even if was actually present (Sanders et al., 2012). If we want to hold onto the idea that consciousness as subjective experience is something we share with animals, it’s not obvious why an ability to report one’s experience is necessary to having an experience in the first place. Hence, despite the careful qualifications of the original inventors of the label “vegetative state”, the term has taken on a life of its own and now probably does more harm than good by priming people to think about consciousness as being either “on” or “off” when reality is more complicated, with VS patients as a population being heterogeneous and falling along a broad spectrum of states – not one monolithic neurological or experiential state (Laureys & Boly, 2008).

4.2 Future Developments

The future of coma science will likely involve the further implementation of advanced neuroimaging technology into the standard practice of clinical diagnosis. Already research teams across the globe are racing to build the first truly validated “consciousness-o-meter” that can be used to quickly diagnosis an unresponsive patient’s level of consciousness without relying on traditional behavioral assessment scales which rely on the subjective judgment of expert raters (Casali et al., 2013). The future will also involve the development of better brain-computer interface techniques to interact with UWS patients who emerge into locked-in syndrome, such as Sorger et al.’s (2013) real-time fMRI speller method (Fig. 2). The future will also bring new developments in therapeutic intervention to help foster neural plasticity and functional recovery using stimulation techniques like transcranial direct current stimulation (tDCS) or deep brain stimulation (Schiff et al., 2007) in addition to pharmacological interventions using anti- insomnia drugs like zoldipem (Brefel-Courbon et al., 2007).


Fig. 2 From (Sorger et al., 2013).


The concept of vegetative state has been loosely recognized, categorized, and discussed for thousands of years but it has only really been in the last 40 years or so that the condition has been rigorously defined and studied using the modern methods of clinical science. Ironically, the more rigorously VS is studied the fuzzier its definitional boundaries become, with most researchers now conceiving of the VS “state” as just one specific band in a continuous, multidimensional spectrum of cognition function. Thus, the more we study the vegetative state the more we realize that the term itself should be abandoned and replaced with a clinically validated set of consistent terminology based on an conceptually and empirically coherent understanding of consciousness that acknowledges a spectrum of possible states a patient could be in when they are seemingly unresponsive to the proddings an external observer.


Brefel‐Courbon, C., Payoux, P., Ory, F., Sommet, A., Slaoui, T., Raboyeau, G., … & Cardebat, D. (2007). Clinical and imaging evidence of zolpidem effect in hypoxic encephalopathy. Annals of neurology, 62(1), 102-105.

Casali, A. G., Gosseries, O., Rosanova, M., Boly, M., Sarasso, S., Casali, K. R., … & Massimini, M. (2013). A theoretically based index of consciousness independent of sensory processing and behavior. Science translational medicine, 5(198), 198ra105-198ra105.

Clarke, E. (1963). Apoplexy in the Hippocratic writings. Bulletin of the History of Medicine, 37, 301.

Giacino, J. T., Ashwal, S., Childs, N., Cranford, R., Jennett, B., Katz, D. I., … & Zasler, N. D. (2002). The minimally conscious state definition and diagnostic criteria. Neurology, 58(3), 349-353.

Giacino, J. T., Kalmar, K., & Whyte, J. (2004). The JFK Coma Recovery Scale-Revised: measurement characteristics and diagnostic utility. Archives of physical medicine and rehabilitation, 85(12), 2020-2029.

Gosseries, O., Bruno, M. A., Chatelle, C., Vanhaudenhuyse, A., Schnakers, C., Soddu, A., & Laureys, S. (2011). Disorders of consciousness: what’s in a name?. NeuroRehabilitation, 28(1), 3-14.

Jennett, B. (1976). Resource allocation for the severely brain damaged.Archives of neurology, 33(9), 595-597.

Jennett, B., & Plum, F. (1972). Persistent vegetative state after brain damage: a syndrome in search of a name. The Lancet, 299(7753), 734-737.

Jennett, B., & Bond, M. (1975). Assessment of outcome after severe brain damage: a practical scale. The Lancet, 305(7905), 480-484.

Karenberg, A. (1994). Reconstructing a doctrine: Galen on apoplexy. Journal of the History of the Neurosciences, 3(2), 85-101.

Koehler, P. J., & Wijdicks, E. F. (2008). Historical study of coma: looking back through medical and neurological texts. Brain, 131(3), 877-889.

Laureys, S., & Boly, M. (2008). The changing spectrum of coma. Nature Clinical Practice Neurology, 4(10), 544-546

Laureys, S., Celesia, G. G., Cohadon, F., Lavrijsen, J., León-Carrión, J., Sannita, W. G., … & Dolce, G. (2010). Unresponsive wakefulness syndrome: a new name for the vegetative state or apallic syndrome. BMC medicine, 8(1), 68.

Levy, N., & Savulescu, J. (2009). Moral significance of phenomenal consciousness. Progress in brain research, 177, 361-370.

Monti, M. M., Vanhaudenhuyse, A., Coleman, M. R., Boly, M., Pickard, J. D., Tshibanda, L., … & Laureys, S. (2010). Willful modulation of brain activity in disorders of consciousness. New England Journal of Medicine, 362(7), 579-589.

Owen, A. M., Coleman, M. R., Boly, M., Davis, M. H., Laureys, S., & Pickard, J. D. (2006). Detecting awareness in the vegetative state. Science, 313(5792), 1402-1402.

Posner, J., Plum, F., Saper, C., Schiff, N., &.(2007). Plum and Posner’s Diagnosis of Stupor and Coma. Oxford, UK: Oxford University Press.

Sanders, R. D., Tononi, G., Laureys, S., & Sleigh, J. (2012). Unresponsiveness≠ unconsciousness. Anesthesiology, 116(4), 946.

Schiff, N. D., Giacino, J. T., Kalmar, K., Victor, J. D., Baker, K., Gerber, M., … & Rezai, A. R. (2007). Behavioural improvements with thalamic stimulation after severe traumatic brain injury. Nature, 448(7153), 600-603.

Sebel, P. S., Bowdle, T. A., Ghoneim, M. M., Rampil, I. J., Padilla, R. E., Gan, T. J., & Domino, K. B. (2004). The incidence of awareness during anesthesia: a multicenter United States study. Anesthesia & Analgesia, 99(3), 833-839.

Sorger, B., Reithler, J., Dahmen, B., & Goebel, R. (2012). A real-time fMRI-based spelling device immediately enabling robust motor-independent communication. Current Biology, 22(14), 1333-1338.

Stender, J., Gosseries, O., Bruno, M. A., Charland-Verville, V., Vanhaudenhuyse, A., Demertzi, A., … & Laureys, S. (2014). Diagnostic precision of PET imaging and functional MRI in disorders of consciousness: a clinical validation study. The Lancet.

Storey, C. E. (2007). Apoplexy: Changing Concepts in the Eighteenth Century. In Brain, Mind and Medicine: Essays in Eighteenth-Century Neuroscience (pp. 233-243). Springer US.

Teasdale, G., & Jennett, B. (1974). Assessment of coma and impaired consciousness: a practical scale. The Lancet, 304(7872), 81-84.

Walker, A. E. (1998). The Genesis of Neuroscience. The American Association of Neurological Surgeons

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