What’s New in Consciousness?

April 18, 2012

I am just back from the four-day “Toward a Science of Consciousness” conference in Tucson. I heard 32 papers on a wide variety of topics and I’m trying to tell myself what I’ve learned about consciousness. Today, I’ll focus on the most fundamental of the difficulties in this area, known to afficionados as “the Hard Problem of consciousness”. The following four statements explain the problem in a way that leaves open to many different kinds of response to it.

1. Data concerning our sensations and feelings correlate with data concerning the firings of neurons in our brains.

There is overwhelming evidence for this statement. Strokes in the back of the head, or severe injuries there, cause loss of vision. The extent of the area in which one can no longer see is well correlated with the extent of the damage. Pin pricks normally hurt; but if injury or drugs prevent  the neural signals they cause from reaching the brain, you won’t feel a thing. Direct electrical stimulation of some brain locations produces experiences. And so on.

2. What neurons do is to fire or not fire.

Neurons can fire faster or slower. There can be bursts of rapid firing, separated by intervals of relative quiescence, and there can be patterns of such bursts. With 100 billion or so neurons, that allows an enormous range of possible combinations of neural activities. We know of no other aspects of neural activity that are relevant to what we are experiencing.

3. We experience a large number of qualities – the colors, the tastes, the smells, the sounds, feelings like warmth, itchiness, nausea, and pain; and feelings such as jealousy, anger, joy, and remorse.

4. The qualities noted in 3. seem quite different from the neural firing patterns in 2, and from any complex physical property.

The Hard Problem is this: What is the relation between our experiences and their qualities, and our neural firing patterns? How can we explain why 1. is true?

There are two fundamental responses to the Hard Problem, and many ways of developing each of them. They are:

Physicalism. Everything is physical. Experiences are the same things as neural events of some particular kind. (It is not claimed that we know what particular kind of neural event is the same as any particular kind of experience.) The explanation of 1. is that the data concerning experiences and neural events are correlated, since experiences and neural events are just the same thing. It’s like the explanation of why accurate data about Samuel Clemens’ whereabouts would be perfectly correlated with accurate data about Mark Twain’s whereabouts.

Dualism. Experiences are not identical to neural events. 1. is true either because neural events cause experiences, or because some events have both neural properties and other properties that cannot be discovered by the methods of science.

Today, the dominant view (about two to one, by my unscientific estimate) is physicalism. The reason is suggested by my descriptions. Dualists evidently have to say how neural events can cause experiences, or explain the relation between the properties known to science and the properties not known to science. Physicalists have no such task: if there is just one thing under two names, there is no “relation” or “connection” to be explained.

But physicalism has another task, namely, to explain how 4. can be true. According to physicalism, blueness = some complex physical property X, the feeling of nausea = some complex physical property Y, and so on. How could these pairs of items even seem to be different, if they were really just the same?

Of course, it will not do to say that blue is the way a physical property X appears to us, the feeling of nausea is the way a physical property Y appears to us, and so on. That would just introduce ways things appear. But then we would just have to ask how physical properties are related to their ways of appearing. They do not appear as what (according to physicalism) they really are; i.e., they do not appear as complex physical properties. So how, according to physicalism, could it happen that X can appear as blue, but not as complex physical property X, if blue = X?

The new developments reported at the conference that were of most interest to me were attempts by physicalists of ways of dealing with this last question. Here are brief summaries of two key ideas.

A. To be feeling something is nothing other than to record and adjust action in the following ways. (i) Recognize dependence of changes of input to one’s sensory devices upon movement of one’s own body. (ii) Recognize changes of input to one’s sensory devices from sources that do not depend on one’s own body (and distinguish these from the changes in (i)). (iii) Process some parts of input more intensively than others. (When we do this, it is called attending to some aspects of our situation more than others.)

We understand how these features could be instantiated in a robot; so we understand how we could make a robot – a purely physical thing – that feels.

B. What is in the world is all physical. Experienced qualities like blue and the feeling of nausea are not in the world – they are its “form”, not its “content”. So, there is no question of “relating” experienced qualities to what is in the world – in fact, it is misleading to speak of “experienced qualities” at all, since that phrase suggests (falsely, on this view) they are something that is in the world.

It’s time for disclosure: I am a dualist. Not surprisingly, I didn’t find either of these efforts to offer a good solution to what I see as the key problem for physicalism. I’ve done my best to represent A. and B. fairly, but you should, of course, remember that what you’re getting here is what a dualist has been able to make of physicalists’ efforts.


How Does Your Food Taste?

March 26, 2012

One question I’ve thought about, without much success, is what exactly is different about our neural firings when we have different sensations. Imagine, for example, looking at a ripe, red tomato on a white tablecloth. Now imagine everything the same, except that you’ve replaced the tomato with an unripe green one of the same size. It’s a sure bet that something different is happening in the back of your head that’s different in these two cases. We know some parts of the story about this kind of difference, but it would be nice to have a full and detailed accounting.

I thought I might get some enlightenment about this question by looking up what’s known about tastes. I suspected that this might be a somewhat simpler case, because I knew that despite the complexity of the lovely tastes that emerge from my wife’s exquisite cooking, they are all combinations of just five basic tastes – sweet, salty, sour, bitter, and umami.

Or, then again, maybe not.

The article that causes my doubts was published by David V. Smith and colleagues in 2000, but I was unaware of it until recently. The Wikipedia entry for “Taste” is organized around the above five “basic” tastes, so perhaps others have also missed this article.

The key problem about taste arises from the fact that taste buds are generally sensitive to many different chemicals. They differ in the degree to which different substances will raise their activation, but they will show some amount of increased activation for many different components of the foods we eat.

This fact supports the view that the cause of a taste is a set of relative degrees of activation across many taste buds. Moreover, we cannot think of each taste bud as devoted to one of the five tastes, and the pattern of relative degrees of activation as a pattern of five kinds of response. Instead, there is a pattern of greater and lesser activations of cells, each of which responds in one degree or another to many kinds of inputs.

A natural question is how the five-basic-taste theory has seemed so good for so long. According to Smith and colleagues, the answer lies in a certain methodological practice. This method involves identifying different kinds of taste buds by their “best response”. That means, for example, that a cell will be classified as a “sweet” cell if its activation is raised more by glucose than by other inputs such as salt or quinine.

Such classifications tend to obscure the point that a so-called “sweet” cell will also be activated by things that aren’t sweet. They may be highly activated by other substances, just not as much so as by glucose.

An even more important point is that the results of this method depend on one’s choice of substances used in comparing relative activations. Smith and colleagues identify another set of chemicals that are quite different from the usual ones, but that, using the same methodology, would give a different set of “basic” tastes. This result casts doubt on the utility of the “best response” methodology for identifying basic tastes.

More generally, it suggests, at least to me, that the story about the neural activations that underlie the differences among our sensations will turn out to be very complex, and will involve patterns of activity across a large number of neural cells.

Bon appetit!

[ David V. Smith, Steven J. St. John, John D. Boughter, Jr., (2000) “Neuronal cell types and taste quality coding”, Physiology and Behavior 69:77-85. ]


Is There an Appearance/Reality Distinction for Pain?

January 23, 2012

In a recent article, philosopher Kevin Reuter has provided an interesting example of experimental philosophy that challenges a widely held view.

The background is that many philosophers (including me) hold that there is no appearance/reality distinction for pain. Pain is nothing but a feeling, so if you have a painful feeling there is no question but that you have a pain. You can be fooled about what is causing you to have the pain; for example, you might think you’ve got a tumor when it’s just a cyst. But you can’t be fooled about whether you are suffering. (Another author in the same journal humorously imagines lack of success for a doctor who would refuse to prescribe painkillers, explaining that the patient is only having an appearance of pain, not a real one.)

There are parallels for our “outer” senses. You can, for example, be fooled about what color a thing is, because you might be looking at it in bad lighting. But you can’t be fooled about the way it *looks*. You might inadvertently pick the wrong word for the color a thing looks to you, but hardly makes sense to say that a thing might seem to look to you other than the way it does look to you. The way a thing looks just is its appearance, and while things in your kitchen can appear other than they really are, appearances themselves can do no such thing.

Many leading views say that the same thing holds for pain. There is simply no difference between feeling a pain, or having something appear to you as a pain, and actually having a pain.

Many leading philosophers also believe that this view – “There is no appearance/reality distinction for pains” – is not a philosophical theory. They are not claiming to say what people *ought* to believe about pains and they are not claiming to have made a philosophical discovery. They regard themselves as merely making explicit what is already implicit in the way people in general speak about their pains.

It is this attribution to the general public of the “No appearance/reality distinction for pains” view that Reuter directly challenges.

The key ground for the challenge is something one does not often see in a philosophy paper. It is a statistical analysis of remarks by non-philosophers – in this case, remarks found on health-related internet sites. Reuter gives details about his methods of search and analysis, but I will just summarize the key results, which I think his evidence clearly supports.

To wit: (1) People use both “I feel a pain” and “I have a pain” (and grammatical variants) in reporting both mild pains and severe pains. However, (2) “feel” is used about as often as “have” when mild pains are referred to, whereas “have” is used far more often than “feel” when the reported pain is severe (about 6 times as often on average, ranging from equally often to 14 times as often, depending on exactly what word — e.g., “major” , “severe”, “bad” — is used).

Result (2) is then combined with another observation: When people use variants of “seems” (e.g., “feels” “looks”, “sounds like”, etc.) in the case of senses such as touch, vision, or audition, they are making an appearance/reality distinction, and they are indicating lower confidence in their judgment. For example, if you speak of a blue tie, or say a tie is blue, you are confidently committing yourself to the claim that the tie is blue. But if you say it looks blue, you are leaving open the possibility that it might not really be blue, and that the way it looks – its appearance – is misleading as to how it really is.

The conclusion is then drawn that the difference in frequency of use of “feel” versus “have” that correlates with mildness versus severity of pain indicates that, at least for mild pains, people – users of health-related internet sites – are making an appearance/reality distinction.

Of course, this conclusion depends on supposing that there is not a better explanation of the correlation between “feel”/”have” and mild/severe. Reuter considers several more or less plausible alternative explanations, and adequately rebuts them. The most plausible of these is that “I have a pain” is, implicitly, a request for help. If the pain is mild, there may be no need for help, so the person reduces the help-seeking implication by using “feel” instead of “have”.

Reuter’s point about this suggestion is that more direct means of seeking aid are easily available, so it is unlikely that pain reports have the function of indirectly asking for help.

There is, however, a variant of this alternative that Reuter does not consider. People know that others are likely to empathize with a reporter of pain. So, if the pain is mild, the person who reports it may want to convey something like “Don’t worry, don’t feel bad for me, it’s only a little pain”. Perhaps using “feel” is a way of indicating this lack of need for empathy.

Of course, it’s unlikely that anyone thinks explicitly that this is what they are doing. So, we might wonder whether such an unconscious adjustment of language is too subtle to be plausible. I do not think so. Consider the shades of politeness in the following list:

Shut the door.

Shut the door, ok?

Would you shut the door?

Please shut the door.

Would you shut the door, please?

If you’ll shut the door, we’ll be less likely to be interrupted.

Which of these we use depends on how we are related to the person we’re addressing, and on circumstances. We do use different degrees of politeness, and we may sometimes pay careful attention to how to put a request. But on many occasions, we tailor what we say to relationships and circumstances without reflecting on or attending to our choice of phrasing, or even realizing that we are adjusting our words to relationships and circumstances. So, perhaps we are sometimes engaging in a similar, unreflective shading of politeness when we say that we “feel a pain” instead of that we “have a pain”.

Whether or not that is a good explanation, we should not forget result (1): People sometimes use “feel” even for severe pains that they cannot plausibly be taken to regard as unreal.

[Kevin Reuter (2011) “Distinguishing the Appearance from the Reality of Pain” _Journal of Consciousness Studies_ 18(9-10):94-109.]