05/12/2010 by admin.

The OnTheHuman site has an article by J. Prinz (here). I certainly like his approach and find his arguments very convincing.

We … ask which of our psychological states can be conscious. Answers to this question range from boney to bulgy. At one extreme, there are those who say consciousness is limited to sensations; in the case of vision, that would mean we consciously experience sensory features such as shapes, colors, and motion, but nothing else. This is called conservatism (Bayne), exclusivism (Siewert), or restrictivism (Prinz). On the other extreme, there are those who say that cognitive states, such as concepts and thoughts, can be consciously experienced, and that such experiences cannot be reduced to associated sensory qualities; there is “cognitive phenomenology.” This is called liberalism, inclusivism, or expansionism. If defenders of these bulgy theories are right, we might expect to find neural correlates of consciousness in the most advanced parts of our brain. …

Not only do I think consciousness is restricted to the senses; I think it arises at a relatively early level of sensory processing. Consider vision. According to mainstream models in neuroscience, vision is hierarchically organized. Let’s consider where in that hierarchy consciousness arises. … I think consciousness arises at the intermediate level. We experience the world as a collection of bounded objects from a particular point of view, not as disconnected, edged, or viewpoint invariant abstractions. … I think this is true in other senses as well. For example, when we listen to a sentence, the words and phrases bind together as coherent wholes (unlike low-level hearing), and we retain specific information such as accent, pitch, gender, and volume (unlike high-level hearing). Across the senses, the intermediate-level is the only level at which perception is conscious. …

Expansionists say we can be conscious of concepts and thoughts, and that such experiences outstrip anything going on at the intermediate-level of perception. … Associative visual agnosia … cannot recognize objects, but they seem to see them. When presented with an object, they can accurately describe or even draw its shape, but they can’t say what it is. Bayne thinks their experiences are incomplete. He thinks knowing the identity of an object changes our experience of it. This is intuitively plausible. … Instead, we can suppose that our top-down knowledge of the meaning changes how we parse the image. … imaginatively impose a new orientation; we segment figure and ground; and we generate emotions and verbal labels, which we experience consciously along with the image; these are just further sensory states—bodily feelings in the case of emotions, and auditory images in the case of words. I think features of this kind can also explain what is missing in agnosia. Without meaning, images can be hard to parse, and associated images and behaviors do not come to mind.

Another argument comes from Charles Siewert. He focuses on our experience of language. Sometimes, when hearing sentences, we undergo a change in phenomenology, and that change occurs as a result of a change in our cognitive interpretation of the meanings of the words. … Phenomenology also changes when we repeat a word until it becomes meaningless, or when we learn the meaning of a word in a foreign language. In all these cases, we experience the same words across two different conditions, but our experience shifts, suggesting that assignment of meaning is adding something above and beyond the sound of the words. … But there are many sensory changes that take place as a result of sentence comprehension. First, we form sensory imagery. … Second, comprehension effects parsing. … Third, comprehension entails knowing how to go on in a conversation … Fourth, meaning effect emotions. …

The third argument I will consider comes from David Pitt. He begins with the observation that we often know what we are thinking, and we can distinguish one thought from another. This knowledge seems to be immediate, not inferential, which suggests we know what we are thinking by directly experiencing the cognitive phenomenology of our thoughts. The most obvious reply is that knowledge of what we are thinking is based on verbal imagery. … I think this is a kind of illusion. We erroneously believe that we are directly aware of the contents of our thoughts when we hear sentences in the mind’s ear. This belief stems from two things. First, we often use verbal imagery as a vehicle for thinking …Second, when contemplating a word that we understand, we can effortlessly call up related words or imagery, which gives us the impression that we have a direct apprehension of the meaning of that word. Our fluency makes us mistake awareness of a word for awareness of what it represents. …

Putting these points together, I think restrictivsts should admit that thinking has an impact on phenomenology, but that impact can be captured by appeal to sensory imagery including images of words, emotions, and visual images of what our thoughts represent. Expansionists must find a case where cognition has an impact on experience, without causing a concomitant change in our sensory states. That’s a tall order.

At this point the dispute between restrictivists and expansionists often collapses into a clash on introspective intuitions. … By way of conclusion, I will try to break this stalemate by sketching five reasons for thinking restrictivism is preferable even if introspection does not settle the debate.

Next comes the arguments for excluding cognitive phenomenology.

1. To make a convincing case for cognitive phenomenology, expansionists should find a case where the only difference between two phenomenologically distinct cases is a cognitive difference. But so far, no clear, uncontroversial case has been identified.

2. The second argument points to the fact that alleged cognitive qualities differ profoundly from sensory qualities in that the latter can be isolated in imagination. … If other qualia can be isolated, why not cognitive qualia?

3. Third, it is nearly axiomatic in psychology that we have poor access to cognitive processes. … The only processes we ever seem to experience consciously are those that we have translated, with great distortion, into verbal narratives.

4. A fourth argument follows on this one. The incessant use of inner speech is puzzling if we have conscious access to our thoughts. Why bother putting all this into words when thinking to ourselves without any plans for communication? …

5. Finally, expansionism seems to dash hopes for a unified theory of consciousness. … But there is little reason to think a single mechanism could explain how both perception and thought can be conscious, if cognitive phenomenology is not reducible to perception. This is especially clear if the mechanism is attention. There is no empirical evidence for the view that we can attend to our thoughts. There are no clear cognitive analogues of pop-out, cuing, resolution enhancement, fading, multi-object monitoring, or inhibition of return. Thoughts can direct attention, but we can’t attend to them. Or rather, thoughts become objects of attention only when they are converted into images, words, and emotions. Expansionists might say that thought and sensations attain consciousness in different ways, but, if so, why think that the term “consciousness” has the same meaning when talking about thoughts, if it does not refer to the same mechanism?

This fits with the idea that only what enters the cortex through the thalamus, can be involved in the thalamo-cortical loops that synchronize their firing during the conscious experience. This category is sensory input (except the bulk of smell) and input about movement and emotion input via the basal ganglia.

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21/10/2010 by admin.

Perception of shapes is possible by touch and by sight. Kim and Zatorre have been using a coding of shape information into sound information to examine the nature of shape perception. They use boards with 2D drawings on them have textured surfaces giving visual and tactile targets. These are coded to give matching ’soundscapes’ where one dimension is coded by frequency and the other by stereo panning. With current and previous experiments, they show that subjects can be trained to identify both visual and tactile targets from soundscapes. Further subjects trained to match sound and touch can do the matching of sight and sound without further training.

Here is the abstract:

Shape is an inherent property of objects existing in both vision and touch but not audition. Can shape then be represented by sound artificially? It has previously been shown that sound can convey visual information by means of image-to-sound coding, by whether sound can code tactile information is not clear. Blindfolded sighted individuals were trained to recognize tactile spatial information using sounds mapped from abstract shapes. After training, subjects were able to match auditory input to novel auditory-tactile pairings. Furthermore, they showed complete transfer to novel visual shapes, despite the fact that training did not involve any visual exposure. In addition, we found enhanced tactile acuity specific to the training stimuli. The present study demonstrates that as long as tactile space is coded in a systematic way, shape can be conveyed via a medium that is not spatial, suggesting a metamodal representation.

Not mentioned in the abstract is their theory of what these experiments say about the perception of shapes.

This transfer of crossmodal learning further supports our hypothesis that shape can be represented at a highly abstract level in a form independent of the sensory modality in which it is learned. This amodal, abstract representation of shape is closely associated with the findings of human imaging studies that identified the lateral occipital region as a common brain region involved in shape recognition by both vision and touch and by audition using the same type of sound transformation used in the current study.

It is interesting to think of shape perception as a link between two aspect of perception: the housing of our perceptions in a three dimensional space and the separation of our perceptions into distinct objects. Both of these seem hardwired and at the foundation of the form our conscious awareness takes.

Kim, J., & Zatorre, R. (2010). Can you hear shapes you touch? Experimental Brain Research, 202 (4), 747-754 DOI: 10.1007/s00221-010-2178-6

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18/10/2010 by admin.

There were two recent items in ScienceDaily reporting two sides of the brain’s flexibility. In one paper S. Lomber and others reported that in cats born deaf, vision is reorganized to use the neural space that is usually used by hearing. This gives better localization in peripheral vision and better motion detection. (here) In the other paper J. Rauschecker and others found that people blind from birth show fMRI activity in visual modules from sound and touch stimuli. These modules analyzed spatial location, patterns and motion. (here)

There are some interesting aspects of this plasticity. First, the ‘born’ in born deaf and born blind is probably very important. If the eyes are not signaling then the visual cortex is not undergoing the developmental stage that ties it to vision. If the ears are not signaling then the auditory cortex is not tied to hearing. This lack of the normal connection probably allows unusual connections to be made more easily.

Second, parts of the cortex that do not get normal stimulation take on stimulation from neighbouring parts of the cortex – rather than being idle or dieing.

Third, aspects of perception like the position of something in three dimensional space can involve more than one sense mode. I can tell where something is by the sound it makes or if trained by the echoes from it; I can tell from the position of my body when I touch it where it is; and I can see where the light is reflected off the object. Location and movement in space is so important to perception that we can think of it as the pre-existing framework that objects are placed in. Location is not so much a product of vision as vision is a tool of location and not its only tool.

Fourth, consciousness has this spatial framework no matter what sense is feeding it. Thus born blind can ’see’ what they hear and the born deaf can ‘hear’ what they see. Seeing really has two meanings, one that means sensory information that comes via the eye and one that means the usual conscious awareness of the world from a viewpoint similar to the eye’s. Hearing also has two meanings. Hearing is what we get from our ears and it can also mean the part of our consciousness that we know as sound.

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20/09/2010 by admin.

Much of what we know of perception has come from studying illusions. Finding situations were the processes reveal themselves in their ‘mistakes’ give clues to how those processes work under ordinary conditions. Of course, our sensory processes have not actually made a mistake; we have misled them.A new illusion is a new departure because it added the specialized perception of faces to visual effects.

Giovanni Caputo from the University of Urbino has developed an experimental setup involving an observer staring for a long time at their face in the mirror under low light conditions, low enough to weaken colour perception. By a minute of fixed staring the face started to change. By 10 minutes, the subjects had seen:

“(a) huge deformations of one’s own face (reported by 66% of the fifty participants); (b) a parent’s face with traits changed (18%), of whom 8% were still alive and 10% were deceased; (c) an unknown person (28%); (d) an archetypal face, such as that of an old woman, a child, or a portrait of an ancestor (28%); (e) an animal face such as that of a cat, pig, or lion (18%); (f ) fantastical and monstrous beings (48%). ”

You will notice that these percentages sum to more that 100% and so the images in the mirror may have gone through more that one transformation.

Under this situation of prolonged staring at a central fixation, the perception of an object is expected to get weaker or vanish. This is not what happens with faces – in situations were an object should disappear, a face does not but instead is free to become another face. Here is another piece of evidence that perception of faces is very special and not like seeing other things. My way of looking at this illusion is that the object ‘face’ remains in place but the attributes bound to that face disappear in the prolonged fixed staring. Other attributes can then take the place of the original ones.

Interestingly the face in the mirror also loses its identification with the subject’s self and becomes a vision of another. Only the face remains – not the look or the identity. Face appears to be a powerful category, which is probably why we see them anywhere (clouds, cracks) and why we spend so much time looking at people’s faces (not feet or shoulders).

Caputo, G. (2010). Strange-face-in-the-mirror illusion Perception, 39 (7), 1007-1008 DOI: 10.1068/p6466

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23/06/2010 by admin.

Mark Changizi wrote a posting in PsychologyToday about colour qualia (here). He has some good thoughts about colour that stem from his research.

How do we know that your ‘red’ looks the same as my ‘red’? For all we know, your ‘red’ looks like my ‘blue’. In fact, for all we know your ‘red’ looks nothing like any of my colors at all! If colors are just internal labels, then as long as everything gets labeled, why should your brain and my brain use the same labels?…

However, I would suggest that most discussions of rearrangements of color qualia severely underestimate how much structure comes along with our color perceptions. Once one more fully appreciates the degree to which color qualia are linked to one another and to non-color qualia, it becomes much less plausible to single color qualia out as especially permutable…other qualia are deeply interconnected with hosts of other aspects of our perceptions. They are part of a complex structured network of qualia, and permuting just one small part of the network destroys the original shape and structure of the network - and when the network’s shape and structure is radically changed, the original meanings of the perceptions (and the qualia) within it are obliterated. But we’re beginning to know more about what colors are for, and as we learn more, color qualia are becoming more and more like other qualia in their non-permutability…

colors are part of a three dimensional space of colors, a space having certain well-known features. The space is spanned by a red-green axis, a yellow-blue axis, and a black-white axis. These three axes have opponent colors at opposite ends, and these extreme ends of the axes are pure or primary (i.e., not being built via a combination of other colors). All the colors we know of are a perceptual combination of these three axes. For example, burnt orange is built from roughly equal parts yellow and red, and is on the darker side of the black-white dimension…

Our primate color vision is peculiar in its cone sensitivities (with the M and L cones having sensitivities that are uncomfortably close), but these peculiar cone sensitivities are just right for sensing the peculiar spectral modulations hemoglobin in the skin undergoes as the blood varies in oxygenation. Also, the naked-faced and naked-rumped primates are the ones with color vision; those primates without color vision have your typical mammalian furry face…In essence, … our color-vision eyes are oximeters like those found in hospital rooms, giving us the power to read off the emotions, moods and health of those around us. On this new view of the origins of color vision, color is far from an arbitrary permutable labeling system. Our three-dimensional color space is steeped with links to emotions, moods, and physiological states, as well as potentially to behaviors. …

Furthermore, these associations are not arbitrary or learned. Rather, these links from color to our broader mental life are part of the very meanings of color - they are what color vision evolved for…The entirety of these links is, I submit, what determines the qualitative feel of the colors we see. If you and I largely share the same “perceptual network,” then we’ll have the same qualia. And if some other animal perceives some three-dimensional color space that differs radically in how it links to the other aspects of its mental life, then it won’t be like our color space. …its perceptions will be an orange of a different color.

The question now is not why colour? or is you red the same as my red? but why are colours so vivid and beautiful in our consciousness?.

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25/03/2010 by admin.

The MindHacks blog had a link to a interview of Nicholas Humphrey by Alan Saunders in Philosophers Zone (here). Here is another interesting observation from the recording. He is giving a possible reason for consciousness.

…What these experiments establish is a lot of other evidence which corroborates it, is that perception, the representation of things in the world, their characteristics, their physical characteristics, is going on independent of sensation. So that raises the huge question of, OK, well then what is sensation for? In the old days people didn’t need to ask that question because they said, ‘Well sensation is what gives the information for perception. You first have an image, your eye,you sensed that as a set of coloured sensations. You then build up your infer the existence of the objects out there in the world. We now know you don’t need that first step, you can go directly to perception. So, what is sensation for?

…Sensations have some very strange and wonderful properties, chief of which perhaps is their extraordinary thickness in time. Sensations are not instants, they’re not physical instants. Every sensation seems to last for more time than it actually occupies. And so instead of moving through life like a kind of point on a single trajectory, we move through it as a substantial entity. I’ve used the analogy we move through life as in a kind of time-ship which has both a prow and an after-end to it, and space inside to move around.

…So I’ve been trying to come up with a new story about why consciousness should matter and why it should have evolved. … the new line I’m taking is not to be looking for things which consciousness helps us to achieve. It doesn’t give us any particular new skills, it’s not like for example the wings of a bird enables the bird to fly. Your understanding English enables you to understand what I’m saying now. I don’t think consciousness enables us to do anything, what I think it does is it encourages us to do things which we wouldn’t do otherwise; to think about ourselves and relate to the world in ways which we wouldn’t do otherwise.

In other words, consciousness changes our psychology, not in the sense of giving us new cognitive skills, but changing our sense of what it is to be ourselves and what it is to live in the extraordinary world which consciousness delivers to us. Basically, it makes ourselves think of ourselves as being of hugely greater metaphysical significance (we don’t of course use that word ) but simply thinking of ourselves as mattering, of our lives as mattering, and indirectly of course, of other people’s lives as mattering because we have been privileged to have been given this miraculous phenomenon at the centre of our lives.

I have to say that this sounds like an interesting side effect of consciousness rather than a reason for its existence. However, it is worth thinking about.

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22/03/2010 by admin.

The MindHacks blog had a link to a interview of Nicholas Humphrey by Alan Saunders in Philosophers Zone (here). There are a number of interesting observations in the recording. Here is one about the separation of perception and sensation.

…The essential point to make is that seeing, hearing or touch or smelling for that matter, is not a single dimension, it hasn’t got just one dimension to it. It’s terribly important to distinguish perception from sensation. The perception of red means understanding, representing the effect about the world, that there is a traffic light out there and that it has a particular coloured light coming from it, or to take another example, that there’s a tree standing in the forest and that it’s quite a particular shape and position and so on. Those are facts about the world, and we use our eyes, use other senses, to get that kind of other information.

Sensation, by contrast, isn’t about what’s out there in the world, it’s about our own response to the stimulation falling on our sense organs… These two things, sensation and perception, are often confused and it’s been traditional in philosophy and certainly I think it’s most people’s view that actually perception depends on sensation. We only get to know that the traffic light is red because first of all we have a sensation. …

What I try to do in the beginning of the book is to show that actually and amazingly this isn’t the case. Perception proceeds independently of sensation; we don’t have to have the sensation in order to get to know what’s out there in the world. And I go through a lot of examples to make that case. Perhaps the most remarkable is the phenomenon of blind sight. It’s something I guess I was responsible for discovering many years ago when I was working, not with human beings but with monkeys.

As a student in Cambridge I had the opportunity to study a monkey who had the visual cortex at the back of her brain removed. My supervisor had done the experiment. He had established that this monkey was apparently quite blind … I had the chance to spend some time with this monkey, she was called Helen, and over literally a few days, sitting with her, playing with her, it became clear to me that she wasn’t actually as blind as she was meant to be. … But I realised there was something very strange about her vision. There must have been something wrong with her you could have guessed, because she didn’t have any visual cortex to see with, but what I became convinced of was that she didn’t believe that she could see. She didn’t seem to have the evidence in front of her eyes if I can put it like that, that she could see. Although every day she would demonstrate objectively that she could. She would run, climb a tree, she would pick up a bit of chocolate from the floor or whatever it may be, she’d come up and take my hand. Out of that work I began to speculate about the possibility of unconscious vision, visual perception occurring without the possibility, without I should say, the fact of sensation. So the subject wouldn’t understand why they could see or have any reasons to believe that they could see.

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08/02/2010 by admin.

Previously I looked at C. Here is the E in an AtoZ by P. Long in My Brain on My Mind. (here)

Easy Problem. Philosopher’s lingo for the problem in neuroscience of comprehending the neuronal correlates of consciousness. When you see red, what exactly are your neurons doing? When you remember your grandfather’s face, what are your neurons doing? It may be difficult to parse the answer but in principle we can do it. It’s easy. The Hard Problem is the mystery of subjective experience. When long light waves stimulate our neural pathways, why do we experience the color red? And what survival benefit caused our brains to develop, through eons of evolution, an ability to experience a “sense of self,” a self able to see itself as special or heroic or smart or not so smart—as, on occasion, a complete failure?

I am not going to discuss a sense of self here, as it seems self evident that a sense of self is useful.

It is not usually quoted as an example of the hard question. Usually we see colour mentioned. Why does the personal experience of colour seem unexplainable? or at least a different order of mystery from other things?

What is the function of colour? It is definitely not there so that we can know the wavelength of light. We do not need or want to know the wavelength of light and, further more, colour is not a reliable measure of wavelength The colours that we see are ‘corrected’ in so many ways and to such an extent that their mapping to the physical wavelength of light is very approximate. Forget wavelength.

What colour does is to help give us objects. Our experience is of a three-dimensional space that is populated with objects. Objects are created by our perception to have particular locations, sizes and surfaces. We understand the world in terms of its objects and the world at any point in time is just objects in space. We recognize them, remember them, categorize them, name them and so on. Our lives are easier if objects that are not actually shrinking or growing, keep their size no matter how much of our retina they take up. We do not want them to move unless they are mobile even though our eyes are flicking their image around on our retina. We do not want objects to suddenly disappear or appear unless they actually are intermittent. And we do not want the surface of an object to change unless it is actually chemically or physically changing. The light (and sound) that is reflected off (and the feel to touch or smell of) an object is important to recognizing that object – such as noticing the archetypal tiger in the long grass at twilight. What our perception creates is objects and they have surface as important property. Those surfaces have colour as part of their image. So colour is very useful in recognizing and remembering objects.

Why is colour so complex in its nature and so delightful to us? The more complex it is, the more we can differentiate between similar surfaces. As far as delighting us – all the aspects of all our senses delight us or disgust us as appropriate. We build a model of the world; we are aware of parts of that model when we are conscious; we remember that model as we live in it; what is important and memorable in the model at any time is what we attend to and remember.

We do not have an explanation for colour or other aspects of subjective experience, but when put in a biological context, it does not seem any harder than many other questions. When we compare it to other questions in biology, why assume it was somehow different and unsolvable?

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15/01/2010 by admin.

There is a site called Less Wrong that I visit (here) because occasionally there is an outstanding post there. I do not comment on the posts as a rule because it is something of a boys club of AI guys and I don’t feel that I belong. But last week there was a post that got me a little worked up and I commented. My efforts lost me some karma but never mind, I didn’t know I had been playing the Less Wrong game. Here is the comment:

“The local worldview reduces everything to some combination of physics, mathematics, and computer science, with the exact combination depending on the person. I think it is manifestly the case that this does not work for consciousness.”

No it doesn’t work because you have left out BIOLOGY. You cannot just jump from physics and algorithms to how brains function.

Here is the outline of a possible path:

1. We know that consciousness has an important function because it consumes a great deal of energy – that’s how evolution works.

2. Animals move – therefore they must have a model of where they are, where they are going etc. - like the old Swedish joke, ‘I cant yump when I got no place to stood’.

3. To make a model, animals need to sense the environment and translate the info into elements of the model (perception).

4. In order to use the model to plan and monitor motor action, they have to also model themselves – so the model is of the animal-in-the-world - the tree is not the real tree in reality but the modeled tree and the me in the model is not the real me in reality but the modeled me.

5. In order to make a good model that was useful it would have to be a unified global model of the animal in the world – all the parts of the model have to be brought together in order to create the best fit scenario and in order for various functions to use the information.

6. In order to make a good model that could be used to plan and valuate actions it would have to model the needs of the animal such as goals, motivations, emotions etc – the model has to have a theory of mind for the animal - so my thoughts in the model are not my real thoughts in reality but the modeled mind. When we introspect we are aware of our model of ourselves but not of ourselves in reality. Definitions can be a problem here – do we use the word ‘mind’ for cognition or for awareness? For we have trouble if we confuse these two things.

7. To make the model more useful it should be predictive to overcome the time it takes to construct the model – so if ‘now’ is t, then the model would be created from the information the brain has at t-x used to predict what reality will be after x duration where x is the time it takes to construct the model – this allows errors in motor actions to be monitored and corrected because the sensory data coming it does not match the model prediction – even the ‘now’ is a modeled now and not the now in reality.

8. So the biological criteria for a good model are unity, speed, accuracy and predictive power. The elements used to create the model must be easily manipulated in order to achieve these goals and must also be capable of being stored as memories, imagined, communicated etc. The qualia of the model will be anything and everything that is biologically possible and makes a good model. We have the data that the sense organs can measure and some effective ways of representing that information in the model.

So the question “Why red?” can be answered with “Why not – it works.” And the question “Where is the red?” can be answered by “In the structural elements of the model”. If someone has a better way to model the frequency of light, I have never heard of it.

If you cannot envisage this modeling as a sequential computer program that is because it isn’t one. It is a massively parallel assembly of overlapping feedback loops that involve most of the cortex, the thalamus, the basal ganglia and even points in the brain stem. It has more in common with analogue computers then digital ones.

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09/01/2010 by admin.

J. Hoffman in the New York Times writes in ”Taking mental snapshots to Plumb our inner selves’, about the work of R. Hurlburt (here), who is attempting to document the contents of consciousness. The method is to fit a person with a random beeper and instructions to record everything they are aware of when the beeper sounds. The people were later interviewed about each recorded moment of consciousness.

After hundreds of introspective interviews, Dr. Hurlburt still hesitates to generalize from his findings. But he has observed that the basic makeup of inner life varies substantially from person to person.

“My research says that there are a lot of people who don’t ever naturally form images, and then there are other people who form very florid, high-fidelity, Technicolor, moving images,” he said. Some people have inner lives dominated by speech, body sensations or emotions, he said, and yet others by “unsymbolized thinking” that can take the form of wordless questions like, “Should I have the ham sandwich or the roast beef?”

In a 2006 book, “Exploring Inner Experience,” Dr. Hurlburt suggests that these differences may be linked to personality and behavior. Inner speakers tend to be more confident, for example, and those who think in pictures tend to have trouble empathizing with others.

Many feel that this is not a very objective experiment. How do we know that people can or do report their conscious awareness in an isolated moment with accuracy, nothing added and nothing missed.

It may be that turning introspection into a science is as impractical as “trying to turn up the gas quickly enough to see how the darkness looks,” as William James wrote in 1890.

But Dr. Hurlburt remains hopeful. Maybe, he said, “it is possible with our modern technology to take a flash picture in the dark.”

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