Why synesthesia?

Synesthesia is a condition where attributes associated with one sense (say colour with sight) can be experienced in another inappropriate sense (say colour with the perception of musical notes). There are many kinds, and rare ones are still being discovered. There is no longer any question that these are ‘real’ perceptions and not hoaxes. Synesthesia seems to have its roots at the sensory level and is a bottom-up rather than top-down phenomenon. There is evidence for heightened sensory activity levels and of additional connectivity between sensory modalities. A lack of normal ‘pruning’ is one of the possible causes.

 

It is no longer a question that the condition is inherited – it is. But not the specific type of synesthesia. Rather the genetic tendency is for any one or more of 60 odd varieties. Brang and Ramachandran (see citation) discuss the possible reasons for this condition not to be eliminated during evolution. Perhaps it has no disadvantage; perhaps it is a side-effect of a useful gene(s); perhaps it is the extreme of a normal distribution that includes us all.

Another possible explanation is that synesthesia simply represents the tail end of a normal distribution of cross-modality interactions present in the general population. Partial evidence supporting this idea comes as sensory deprivation and deafferentation (i.e., loss of sensory input through the destruction of sensory nerve fibers) can lead to synesthetic-like experiences. For example, after early visual deprivation due to retinitis pigmentosa, touch stimuli can produce visual phosphenes, and after loss of tactile sensation from a thalamic lesion, sounds can elicit touch sensations . More remarkably, arm amputees experience touch in the phantom limb merely by watching another person’s hand being touched. Long-standing evidence has also demonstrated that hallucinogenic drugs can cause synesthesia-like experiences, suggesting the neural mechanism is present in all or many individuals but is merely suppressed. However, no research has yet established the relationship between these acquired forms to the genetic variant and whether the same neural mechanism is responsible for both.

 

And perhaps, synesthesia is actually advantageous. What are some possible plus points?

  1. Synesthesia may assist creativity and metaphor – it is more frequent in creative people and is a little similar to metaphor.

  2. It may assists memory – there is some evidence from savants.

  3. There is enhanced sensory processing – such as finer discrimination of colours

These demonstrations of enhanced processing of sensory information suggest a provocative evolutionary hypothesis for synesthesia: synesthetic experiences may serve as cognitive and perceptual anchors to aid in the detection, processing, and retention of critical stimuli in the world; in terms of memory benefits, these links are akin to a method of loci association. In addition to facilitating processes in individual sensory modalities, synesthetes also show increased communication between the senses unrelated to their synesthetic experiences, suggesting that benefits from synesthesia generalize to other modalities as well, supporting their ability to process multisensory information. Furthermore, others have argued that synesthesia is the direct result of enhanced communication between the senses as a logical outgrowth of the cross-modality interactions present in all individuals.

 

The puzzle of how genetically, how physiologically, and why it is that synesthesia arises will be very illuminating to the questions of how qualia are bound to objects and why we have the vivid conscious experience that we have.

 

ResearchBlogging.org

Brang, D., & Ramachandran, V. (2011). Survival of the Synesthesia Gene: Why Do People Hear Colors and Taste Words? PLoS Biology, 9 (11) DOI: 10.1371/journal.pbio.1001205

Possible functions of consciousness 5 – create ‘now’

In the first four posts in this series, the relationship between memory/imagination and consciousness was the focus. The idea was that there is a structure at the heart of consciousness that is where the experiences for memory are put together, where recalled memories are housed and where imaginings are created. But there seem to be other functions that happen in this structure. One is a slight projection into the future, a prediction – just enough of a forward projection to make up for the lag caused by the work of creating the conscious moment. At the moment of awareness, the incoming sensory data is mirrored by the projection and should be the same if the projection is accurate. Any difference is an error that must be corrected.

 

 

What we have is a loop between action and perception. People often start with the perception but it is just as reasonable to start with the action. I plan an action and part of that plan is a idea of how the world changes during the action. Then I do the action and along the course of the action there is a monitor on how well it is going – the comparison of the conscious ‘now’ and the sensory input. Deviations are used to fine-turn the course of the action.

 

 

Or we can have an idea of what is in the world around us. We can make a projection and compare it with our senses. If there is a discrepancy we know that our idea of the world is wrong and we should change our perception of what is in the world or react to it. Or… we can speed up the picture and it is not a loop in either direction but a meeting of the sensory half and the motor half of the brain with anything and everything tweaked until there is a perfect fit with reality. The aim is to have little tweaks but no big surprises.

 

 

Actually the perfect fit with reality is an illusion. There are many changes in the world that we just do not notice. The system is (as most biological systems are) as good as it has to be but not perfect. This is not the sort of prediction that a computer might do, with a lot of code, complicated equations and great effort. Instead it is probably done with a large number of small heuristic tricks of the sort that give us visual illusions. There is little doubt that the small (in the region of 250 msec) forward projection is done but very little knowledge of the mechanism. It is a feature of our awareness but the doing of it is hidden from us.

 

 

An advantage of having the prediction is that it would highlight conflict between to motor programs. Suppose we are running and bouncing a ball at the same time. The two motor programs are working smoothly together. Then a dog runs into our path intent on having the ball (all balls belong rightfully to every dog). Both motor programs must be quickly adjusted – but what if the adjustments conflict and a particular muscle is going to be given to different signals. The theory goes that the prediction available in consciousness will avoid these conflicts. If this does happen, it would be a valuable function.

 

 

I should mention what I have taken to be a semantic argument between people (see here) who envisage the projection as a dynamic control operation by the motor side of the brain – and on the sensory side, people who envisage a prediction using cognitive calculations on a stimulation. I first encountered this when I ran across someone denying that the conscious experience is a slight prediction. On careful reading, it was the word ‘prediction’ that was the problem because the writer associated it with a particular type of prediction and used ‘prospective control’ for another type of projection into a future time. I really do not have a method that I favour but I believe that the prediction is based on both sensory and motor information and very probably is an assortment of methods.

 

 

So we can give as possible functions of consciousness, the housing in the consciousness structure of a predictive/prospective/projective ‘now’ that covers an awkward lag in awareness, monitors the accuracy of sensory perception, monitors the accuracy of motor control, and perhaps gives warning of conflicting motor commands before they are sent.

 

 

Babel’s Dawn – the book

A number of years back I encountered a blog called Babel’s Dawn written by Edmund Blair Bolles. It is now inactive although all the postings are still on-line to read at http://www.babelsdawn.com . It has been turned into a book called Babel’s Dawn, A Natural History of the Origins of Speech by the same author, EB Bolles. The book is a narrative and a very easy, enjoyable read. It is the same material as the blog but not in essay form. Instead it is ordered chronologically and presented as a walk through a museum exhibition. If you are at all interested in language, human nature, evolution, culture (and I expect many of my readers are interested in that type of subject matter) get the book and have a good read over Christmas.

 

The narrative starts with a character given the name Sara who is the putative last common ancestor of us and Chimps 6 million years ago. Using characters like this at points along the way, language is traced from its roots to something we understand as a proper language over a time span of 5.1 million years. What has to happen further in the last 900,000 years is added at the end. At no place was I left wondering, how it we get from there to here – no almighty leaps – no magic fairy dust.

 

The logic is convincing. It does not rely on many new powers but is grounded in perception, attention, and communal living. It bypasses rules of syntax, symbols, and the like to get a much more biologically based notion of what language is and what it does.

 

The key idea is that apes have the abilities that we adapted into language but they do not use them in the way we do, mainly because they do not trust one another. We are trusting, cooperating, social animals. We jointly pay attention to a topic (Bolles calls this the speech triangle of speaker, listener and topic). It is to our advantage to do this but it is not to the chimps advantage. From this trusting joint attention all else flows. Words steer attention. Verbs connect topics with news about them. Metaphor allows us to treat all things as though they were concrete and could be perceived. The theory make good sense and seems to fit the data.

 

It is a just-so-story and will probably be overtaken by new data and new ideas eventually. Bolles is well aware of that and points it out himself. But it is a very well done tale, very careful with the data, and in my opinion, it is many head-and-shoulders above other attempts to trace language’s origins.

 

Again I urge you to read the book!

 

How similar and how different are our brains?

We all wonder how similar our individual thoughts are. We are fairly sure that our brains are not identical, not like the little worm C. elegans with its 302 neurons and all the synapses mapped. But we are also fairly sure that we have great similarity in the architecture of our brains; we all have the same little motor homunculus across the top of our brains that we see in illustrations. We all have the primary optical perception in predictable locations at the back of the brain. It seems pretty clear that different aspects of brain function have different levels of individuality – content of memories would be almost completely individual while control of muscles would be quite standardized.

Some light has been shone on the subject by J.A. Clithero and others in NeuroImage (see citation). They have compared fMRI scans ‘within-participants’ with those ‘cross-participants’. Where in the brain is there similar BOLD activity for a type of event in a single person and where is there similarity between people?

Nearly all MVPA studies that employ classifiers build an independent classification model for each participant, based on the trial-to- trial variability in the fMRI signal. This approach is well-suited to identify brain regions that play a consistent functional role within- participants, but it cannot make claims about common cross- participant representation. While relatively few studies have adopted the latter approach, some early applications have targeted deception , different object categories, mental states that are consistent across a wide variety of tasks , attention, biomarkers for psychosis, and Alzheimer’s disease . To date, however, no study has systematically evaluated whether within- and cross-participant analyses provide distinct information about brain function.

This is the missing perspective that they were looking at. Here is their abstract:

Analyzing distributed patterns of brain activation using multivariate pattern analysis (MVPA) has become a popular approach for using functional magnetic resonance imaging (fMRI) data to predict mental states. While the majority of studies currently build separate classifiers for each participant in the sample, in principle a single classifier can be derived from and tested on data from all participants. These two approaches, within- and cross-participant classification, rely on potentially different sources of variability and thus may provide distinct information about brain function. Here, we used both approaches to identify brain regions that contain information about passively received monetary rewards (i.e., images of currency that influenced participant payment) and social rewards (i.e., images of human faces). Our within- participant analyses implicated regions in the ventral visual processing stream—including fusiform gyrus and primary visual cortex—and ventromedial prefrontal cortex (VMPFC). Two key results indicate these regions may contain statistically discriminable patterns that contain different informational representations. First, cross-participant analyses implicated additional brain regions, including striatum and anterior insula. The cross-participant analyses also revealed systematic changes in predictive power across brain regions, with the pattern of change consistent with the functional properties of regions. Second, individual differences in classifier performance in VMPFC were related to individual differences in preferences between our two reward modalities. We interpret these results as reflecting a distinction between patterns showing participant-specific functional organization and those indicating aspects of brain organization that generalize across individuals.

 

ResearchBlogging.org

Clithero, J., Smith, D., Carter, R., & Huettel, S. (2011). Within- and cross-participant classifiers reveal different neural coding of information NeuroImage, 56 (2), 699-708 DOI: 10.1016/j.neuroimage.2010.03.057

Possible functions of consciousness 4 – place to imagine

People have noted often that we are conscious of our memory recall from episodic and semantic memory and also of imaginings. That is what it means to recall or to imagine – to be aware of the memory or the imagining. It is as if conscious awareness was a structure into which our awareness of ‘now’ or of some memory of past time or even some imagining of future or fictitious time, can be housed. It has been likened to a work space, a theatre, a model world – for now I am going to call it the conscious awareness structure. It is a 3D space centered on ‘here’, ‘now’ and ‘I’ but with the ‘here’, ‘now’ and occasionally the ‘I’ being ‘virtual’ when dealing with recalled memories or imaginings. We seem to be able to tell the difference between our awareness of the three different sources of the experience. It is not that the mechanics of recall or imagining are conscious but that the awareness of the result is in our conscious experience. I suspect that the same structure is used to house dreams.

It may be (and appears to me likely) that the process of recall is not a simple one. When I try to remember events from long ago, I find that they now incorporate changes or additions that make them fit with my current view of the world. I remember the pinkness of a particular dawn and it is placed in a particular farm yard. It is a familiar image from being recalled many times. Then I run across a photograph of the yard in question and I am surprised that my memory is physically impossible – there is no place in that yard to see the perspective I remember. Now when I recall the dawn it is seen corrected from its previous deviation. When we recall, we must fit the memory into our current conscious awareness structure. Throughout our lives, our bank of memories is reworked, consolidated, updated and so on to keep the bank useful and consistent. Some may think this is a poor way to arranged things. It would be better if evolution had produced an indelible, accurate trace of our past. But the purpose of our memories is not accuracy or permanence; it is usefulness because memory gives the elements used to think, solve problems, learn, plan the future, invent, avoid disaster. If I buy a new stove, I still want to use the lessons I learned on my old stove, not re-learn cooking with each change in my kitchen. Old memories have to be made to fit in the current structure of our awareness or they become useless. Little and large bits of memory are part of the stuff of thought.

We may (and again it appears to me likely) use fragments of memory to create imaginings. Stripped of their reference to a particular event, fragments can be furnish the pieces of an image – a tree here and a park bench there. Tulving’s notions of mental time travel and the possible connection of amnesia and inability to imagine are pointers to this sort of use of memory for imagining. These fragments used to form imaginings do not effect the original memory though, because the context of the original memory has to be part of the reworking that can occur with memory recall.

How important is the link between memory and consciousness? David Chalmers postulates the idea of a type of zombie that is indistinguishable from a conscious person but lacks consciousness. He says because we can envisage such zombies, they must be logically possible and therefore….well, many things follow. But it does not seem to me that his idea of zombies can be envisaged. People without consciousness would be very distinguishable from those without. A person without consciousness is likely to have no memory or a very poor one and no imagination or a very poor one. They would be very poor learners and speakers. The fluid easy flow of elements between consciousness and memory is extremely important to how the brain works. The conscious awareness structure is a very important component of the brain. It is well worth its cost in biological terms.

In the next post in the series, I am going to leave the memory connection and deal with other possible functions of consciousness. The reason for examining memory first is that I think it is neglected in discussions of consciousness.

There is more to come. Previous posts in this series:

Possible functions of consciousness 1 – leading edge of memory

Possible functions of consciousness 2 – gate to meaning

Possible functions of consciousness 3 – working memory

Uniqueness

Quantity has a quality all its own“, which Stalin may or may not have said, is worth thinking about. Many inquiries start with a qualitative difference between man and other animals. This all-important difference is searched for and guessed at. The effort to find the unique x has disrupted and distorted the normal scientific path. On the other hand, quantitative differences between us and other species is a much more fruitful objective to search for.

Here is a quote from Marc Bekoff in a recent post (here):

For as long as human animals have pondered how we might differ from nonhuman animals (hereafter animals for convenience) many ideas have come and gone. For example, it’s been postulated that humans are created in the image of God and are the only rational beings. People vary in their opinions on whether we are the only animals who are created in the image of God and of course it’s not a claim that can be proven or disproven. However, ample research has shown that animals are rational beings and that they also share with us many other traits that were once thought to be uniquely human, including manufacturing and using tools, having culture, having a sense of self, using complex systems of communication, producing art, and having rich and deep emotional lives and knowing right from wrong. Two traits that seem to separate us from other animals are we’re the only animals who cook food and no other animals are as destructive and evil…

The time has come to debunk the myth of human exceptionalism once and for all. It’s a hollow, shallow, and self-serving perspective on who we are. Of course we are exceptional in various arenas as are other animals. Perhaps we should replace the notion of human exceptionalism with species exceptionalism, a move that will force us to appreciate other animals for who they are, not who or what we want them to be.

Separating how we think about humans and other animals is like separating how we think about rivers and the Nile. It is not an efficient way to understand the Nile and it robs effort from understanding rivers in general. The only way this sort of thing happens if we start with “the Nile is not a river”, “don’t use concepts that describe the Nile for any other river (nilomorphism to coin a word)” or “it belittles the Great Nile to say it behaves like other rivers”. We have built an artificial boundary here, we have not ‘divided nature at its joints’. We will sink down to playing semantic games – trying to define Nile so other rivers are not included and trying to define river so that it includes them all except for the Nile. In the same way, dividing man from other animals is also artificial – not the way science should be done.

Human uniqueness has been a sort of holy grail. People have been searching for this mythical piece of knowledge – what is the important distinction. But the important knowledge is the ability to trace how all those things that we share with the other animals have been mixed and modified to produce the unexceptional uniqueness of all animal species. No part of our makeup and our culture started from nothing; everything (gene, gene-like, meme or meme-like) has evolved to its present state; it had evolutionary roots. Science should not be trying to separate us from other animals but should be drawing the connections. By and large Biology has been doing this for years but with the newer brain sciences it has been tough trying to break through the mind-set that humans are unique in a unique way.

 

I'm on ScienceSeeker-Microscope

Primitive brain

I have this picture that appeals to me but for which I have never had an evidence. It is not something I believe or even suspect may possibly be true, more an outside chance but interesting.

 

Think of the brain stem-part of the brain. In some early organism it was all the brain there was and it did everything. It was not that clever but it was in charge of the whole show. Even now if we have a fair amount of the ancient brain alive we can survive in a vegetative state. We can think of that primitive brain having grown its own on-line computer in the form of the mid-brain. Then later, the mid-brain having grown its own on-line computer in the form of the fore-brain. Each layer has deputized a new layer to do some of its functions while keeping some of its control intact.

 

For example the area that controls whether we are alert or asleep is deep in the brain stem. It causes the thalamus to be either alert or not. The thalamus causes the cortex to be conscious or not.

 

Science Daily has an item about research of E. Miller of MIT cited below:

Our brains have evolved a fast, reliable way to learn rules such as “stop at red” and “go at green.” Dogma has it that the “big boss” lobes of the cerebral cortex, responsible for daily and long-term decision-making, learn the rules first and then transfer the knowledge to the more primitive, large forebrain region known as the basal ganglia, buried under the cortex.

Although both regions are known to be involved in learning rules that become automatic enough for us to follow without much thought, no one had ever determined each one’s specific role…

Their results suggest that the basal ganglia first identify the rule, and then “train” the prefrontal cortex, which absorbs the lesson more slowly….

Common wisdom suggests that when we learn new things, the prefrontal cortex figures things out first. Then, as our behaviors become familiar and habitual, the more primitive, subcortical basal ganglia take over so that the now-familiar routines can be run off automatically and occupy less of our thoughts.

“What we found was evidence for something very different,” Pasupathy said. “We found that as monkeys learn new, simple rules–associations analogous to ‘stop at red, go at green’–the striatum of the basal ganglia shows evidence of learning much sooner and faster than the prefrontal cortex. But, an interesting wrinkle is that the the monkeys’ behavior improved at a slow rate, similar to that of the slower changes in prefrontal cortex.”

This suggests that while the basal ganglia “learn” first, their output forces the prefrontal cortex to change, albeit at a slower rate. The researchers speculate that perhaps the faster learning in the basal ganglia allows us (and our primitive ancestors who lacked a prefrontal cortex) to quickly pick up important information needed for survival. The prefrontal cortex then monitors what the basal ganglia have learned. Its slower, more deliberate learning mechanisms allow it to gather a more judicious “big picture” of what is going on by taking into account more history and thereby exert executive control over behavior.

ResearchBlogging.org

Pasupathy, A., & Miller, E. (2005). Different time courses of learning-related activity in the prefrontal cortex and striatum Nature, 433 (7028), 873-876 DOI: 10.1038/nature03287

Two old ways of learning

The common ancestor of mollusks, arthropods and chordates (sea snail, fruit fly and mouse) was about 530 million years ago. Bjorn Brembs posts on two learning systems that appear to be this old. (here)

Synaptic plasticity which changes the connectivity between neurons seems to have two different chemical routes: (1) neural transmitter, rutabaga adenylyl cyclase, cAMP, PKA, CREB, DNA to give long-term memory (2) similar but a different cyclase enzyme instead of rutabaga, PKC instead of PKA, FoxP instead of CREB.

The two chemical routes can be separated by either a PKC inhibitor or interfering with the FoxP gene. The research has been done on the sea snail, fruit fly and mouse. By killing the PKC route it appears that the PKA route is likely to be used for classical conditioning which relies on external cues and is thought similar to declarative memory. And it appears that the PKC route is likely to be used for operant conditioning which relies on self motion and is thought similar to procedural memory.

If this turns out to be confirmed, it would mean that our two basic memory systems are as distinct as they appear and are very old indeed. It is interesting that the FoxP gene is involved procedural memory – this is a gene that in humans and song birds appears to help facilitate learning language and song. Also interesting is that there may be a link between classic conditioning and declarative (passing through consciousness) memory.

Possible functions of consciousness 3 – working memory

As well as the episodic and semantic types of explicit memory featured in the first two parts of this series (and the implicit or procedural memory which seems to have no connection with consciousness), there is another important type of memory – working memory. How working memory actually works is far from a settled question. It may not be one thing – but several separate working memories. The working memory that I am discussing has these characteristics: it has limited capacity of 7 or less items in memory; it holds those items for a limited time, about a second unless replaced by new items; items being held can be manipulated; the items appear to be in consciousness or extremely easily brought to consciousness; they seem to be the focus of attention or extremely easily made so. This is the working memory that is needed for intelligence and correlates with IQ. It is needed for certain types of accurate detailed calculations and similar cognition. It is needed for creating and interpreting complex sentences. It is required for keeping concentration on a task and some other executive functions. Most descriptions of consciousness include working memory as well as a larger less detailed world view (a global ‘gist’) and attention. Avoiding problems with exactly how both consciousness and working memory are defined and bounded, whether one is a part of the other or they are separate mechanisms – let us just consider them as inseparable under normal conditions.

Daniel Kahneman introduced the terminology of System 1 thinking and System 2 thinking. System 1 is unconscious, automatic, very fast while System 2 is conscious, does orderly reasoning, and is very slow. I think that all actual cognition is like System 1, and System 2 only differs by passing through consciousness.

More and more it appears that cognition is primarily an unconscious activity. We are aware of only a very tiny proportion of the cognition our brains do. And even for that tiny proportion we are not aware of the actual cognition but only of the changes it makes in the items held in working memory. If I add 5 to 17, I am aware of: task is to add 5 to 17, add 5 to 7, that is 12, but it is 17 not 7 so add 10 to 12, answer 22. But I have no awareness of how these steps are done – my awareness just jumps from one step to the next. Even given that the cognition itself is not a function of consciousness – we still seem to require consciousness to feed and hold items in working memory so that they can be manipulated. Tasks that are not sequential are difficult to do using working memory and tasks that are sequential are difficult without working memory. When working memory is used, the changes in what is held in the working memory are registered in consciousness.

Working memory (and therefore consciousness) is involved in doing mental arithmetic because we need the explicit semantic memory to retrieve facts like ’5 plus 7 equals 12′ which we have been taught by rote as small children. The same is true of mental logic, games with rules like bridge or chess, where much of the reasoning is sequential and tends to need explicit memory.

Sentences can be understood or created in a way that seems effortless but it does require a certain amount of juggling – holding this word until it is clear which meaning I should understand by it or which ending is grammatical for it and so on. The words and idiomatic phrases are in semantic memory to be retrieved as needed. Much of the juggling is unconsciously done but the results are past through consciousness for all those cases where working memory is involved.

We need working memory to learn motor skills. Once learned they can be done without working memory or even consciousness. But when learning such motor skills sequence and timing are important and it seems that learning the rough motor idea of a sequence takes the sort of manipulation that can be done on items held in working memory. Once the rough motor program is there, it can be honed and smoothed without consciousness or working memory. Soon there is a high skill level that is disrupted by conscious thought. Golfers must not think about the mechanics of their swing consciously or they will lose their skill.

There is no reason to think of this use of working memory as ‘the conscious mind’. The word ‘mind’ implies a system of cognition; and ‘conscious mind’ implies a system of cognition that is separate from unconscious cognition. However, all the manipulation, all the cognition is not part of awareness. We are not aware of how it is done. We are not aware of how 5 is found a retrieved from memory. It just pops in. All we are aware of is the flow of events, the stream of consciousness. In is more reasonable to think of having one undivided mind which does the work of cognition and a small part of the results rise to consciousness and so we are aware of them – one pop at a time.

So again we come to the function of consciousness. It is involved in a particular type of thinking in that it holds the keys to working memory. This type of thinking is very important to language, mathematics and logic. This function alone would be worth its cost.

hypnosis may be real but rare

A recent paper (citation below) has investigated a particular person who is very easy to hypnotize. The authors make an argument for single case studies at the beginning of an investigation. I found this interesting because I usually feel disappointment in single case studies. This defense seemed to make sense.

 

We propose that the research field of hypnosis should also include an approach that has proven to be very effective in cognitive neuropsychology; namely using detailed case studies as one line of research to make initial theoretical progress in a relatively new and fuzzy area of empirical research. This approach has previously shed new light on many rare phenomena e.g. Capgras syndrome or synaesthesia. Furthermore, such studies have consequently led to better general understanding of brain functioning. However, since we only presented the results of a single case, we cannot draw conclusions about hypnosis in general or even about other hypnotic virtuosos.

 

Two things held them to this study: a particular stare is associated with traces/hypnosis for many observers and some regions of the brain (anterior cingulate cortices and dorsolateral prefrontal cortex) are associated with hypnosis and with control of the eyes. They compared the subject TS-H with a matched group in a normal conscious state, and in a hypnotic one for TS-H and attempting to fake hypnotic stares for the others. The fakers were not without help: they were shown movies to TS-H’s stare and instruction on the various differences between the stare and normal eye movements.

 

We showed that a Hypnotically Induced Stare (HIS) is accompanied by large, objective and inimitable changes in the patterns of eye movements in the case TS-H. The amplitude, velocity and frequency of reflexive saccades were radically suppressed, and the fixation time was increased. Also the pupil size of TS-H diminished during the hypnosis condition.

 

These effects are difficult or impossible to fake and the control group could not – not too surprising as they are automatic actions.

 

We suggest that the hypnotic state does not occur in all who are classified as highly-hypnotizable by using current hypnotisability scales, but only in a small subgroup of them. The external manifestation of those who enter the hypnotic state may be the classical Hypnotically Induced Stare (HIS). However, this result does not rule out the possibility of a hypnotic state being present without accompanying change in eye behaviour.

 

But at least some people can be hypnotized – it is a distinct state of consciousness – it can be objectively observed. Even if suggestibility is a spectrum from people like TS-H and those that completely resist suggestions, it is still clear that the extreme end can be identified and probably cannot be faked. Or if it is rare, it is possible to tell the difference between it and people who are fooling themselves or others. A step forward on the basis of a single case study is causing me to change my prejudice against them.

ResearchBlogging.org

Kallio, S., Hyönä, J., Revonsuo, A., Sikka, P., & Nummenmaa, L. (2011). The Existence of a Hypnotic State Revealed by Eye Movements PLoS ONE, 6 (10) DOI: 10.1371/journal.pone.0026374