Tuesday, July 09, 2013

The Individual Differences Reply to Introspective Pessimism

I'm an introspective pessimist: I think people's introspective judgments about their stream of conscious experience are often radically mistaken. This is the topic of my 2011 book, Perplexities of Consciousness. Over the past few years, I've found the most common objection to my work to be what I'll call the Individual Differences Reply.

Many of my arguments depend on what I call the Argument from Variability: Some people report experiences of Type X, others report experience of Type not-X, but it's not plausible that Group 1 and Group 2 differ enough in their underlying stream of experience to make both claims true. Therefore, someone must be mistaken about their experience. So for example: People used to say they dreamed in black and white; now people don't say that; so someone is wrong about their dream experiences. Some people say that tilted coins in some sense look elliptical as though projected upon a 2D visual screen, while others say that visual experience is robustly 3D with no projective distortions at all. Some people say that objects seen 20 degrees from the point of fixation look fairly clear and colorful, while others say objects 20 degrees from center look extremely sketchy and indeterminate of color. Assuming a common underlying experience, disagreement reveals someone to be mistaken. (Fortunately, we needn't settle which is the mistaken party.)

The Individual Differences Reply challenges this assumption of underlying commonality. If people differ in their experience as radically as is suggested by their introspective reports, then no one need be mistaken! Maybe people did really used to dream in black and white and now they dream in color (see Ned Block's comment on a recent Splintered Mind post). Maybe some people really do see tilted coins as elliptical while others do not.

There are two versions of the Individual Difference Reply, which I will call the Stable Differences and the Temporary Differences versions. On the Stable Differences version, people durably differ in their experiences in such a way as to render their reports accurate as generalizations about their experiences. On the Temporary Differences version, people might be similar in their experiences generally, but when faced with the introspective task itself their experience shifts in such a way as to match their reports. For example, maybe everyone generally has similar experiences 20 degrees into the visual periphery, but when asked to introspect their visual experience, some people experience (and accurately report) clarity while others experience (and accurately report) haziness.

People who have pressed versions of the Individual Differences Reply on me include Alsmith forthcoming, Hohwy 2011, Jacovides 2012 and Hurlburt in Hurlburt & Schwitzgebel 2007.)

Here's how I think the dispute should be resolved: Look, on a case-by-case basis, for measurable brain or behavioral differences that tightly correlate with the differences in introspective report and which are plausibly diagnostic of the underlying variability. If those correlations are found, accept that the reports reveal real differences. If not, conclude that at least one party is wrong about their experience.

Consider black and white dreaming. Theoretically, we could hook up brain imagining machinery to people who report black and white dreams and to people who report color dreams. If the latter group shows substantially more neural activity in color-associated neural areas while dreaming, the reports are substantiated. If not, the reports are undermined. Alternatively, examine color term usage in dream narratives: How often do people use terms like "red", "green", etc., in dream diaries? If the rates are different, that supports the existence of difference; if not, that supports the hypothesis of error. In fact, I looked at exactly this in Chapter 1 of Perplexities, and found rates of color-term usage in dream reports to be the same during the peak period of black-and-white dream reporting (USA circa 1950) and recently (USA circa 2000).

Generally, I think the evidence often shows a poor relationship between differences in introspective report and differences in plausibly corresponding behavior or physiology.

Sometimes there is no systematic evidence, but antecedent plausibility considerations suggest against at least the Stable Differences version of the Individual Differences Reply: It seems highly unlikely that the people who report sharp visual experiences 20 degrees into the periphery differ vastly in general visual capacity or visual physiology from those who report highly indeterminate shape and color 20 degrees into the periphery. But that's an empirical question, so test it if you like!


John Baez said...

Do you think of these questions as more about 'philosophy' or more about more 'psychology'? (Or do you dislike that division?) It seems to me that as long as we can make these questions amenable to empirical tests of some sort, they fall under psychology. Philosophy enters when we're trying to figure out how and whether they're amenable to empirical tests. For example, we can easily imagine someone arguing that it makes no sense to ask whether someone is right or wrong about whether their dreams are in color, and that no empirical tests can answer such a nonsensical question. It might take a philosopher to convince such a person that they're wrong.

Do you see yourself as providing philosophical assistance to what might someday be just a routine branch of science?

Anonymous said...



Eric Schwitzgebel said...

Hi John --

I see myself as working at the border between philosophy and psychology, which I think isn't sharp. Empirical tests in this area need to be interpreted in light of considerations that are big-picture enough to count as philosophical, and philosophical proposals have more or less value depending on the empirical facts that those proposals highlight or idealize away from.

I'm inclined to think that once you back far enough away into the big picture and the overall epistemic grounds of empirical inquiry type X, you are doing philosophy of X (whether your departmental affiliation is Philosophy or not), and so I'm inclined to think that we should always think of the biggest questions about consciousness as part of philosophy -- if also, equally, part of psychology.

Eric Schwitzgebel said...

Anon Jul 10: Thanks for the links! I agree that Rees is doing some of the best work relating conscious experience to neural properties. My experience with these corners of neuroscience is that trends come and go and work doesn't always stand the test of time -- so let's see where this is in 5-10 years. Also, I wouldn't deny that there are *some* good correlations between neural properties and subjective reports, e.g., general damage to visual areas of the cortex and subjectively reported (and behaviorally confirmed) blindness.

Let me clarify that my view is that often -- perhaps surprisingly often -- variations in subjective report don't correlate very well with objective measures. But I certainly wouldn't make the universal claim that they never do.

Arnold Trehub said...

Eric, imagine this situation:

An artist stares at a blank canvas on an easel as you look over his shoulder. Suddenly, an image that was created in the brain of the artist distinctly appears to him to be on the canvas without his making a mark on it. He says that he sees the image right there in front of him, and you believe him because you see an image on the canvas just like the one he describes to you.

How would Introspective Pessimism undercut the introspective report of both parties in this situation?

Mike J. said...

Sometimes there is no systematic evidence, but antecedent plausibility considerations suggest against at least the Stable Differences version of the Individual Differences Reply:

I'm sympathetic with these remarks and with the implicit hesitation about generalizing to the temporary difference view. If two people get an 'x' to disappear into the blind spot, and one person says that the newly present white patch looks clear and another says it looks fuzzy, I don't think that we can expect to find a physiological difference or a difference in capacity between the two subjects.

I bet just about everyone generally sees more than 10 degrees as subjectively clear. Having a playing card approach from the periphery while staring ahead is a special case. I bet that if you ask someone who thinks that only ten degrees are subjectively clear all the time to stop what they're doing and describe the breadth of subjectively clear field, consciously or not, they'll stare straight ahead. You can't generate the feeling of narrow clarity while your eyes are darting about. So, that could be a physiological mark of a temporary difference.

I think that people who can manage the gestalt switch from seeing in three-d to seeing a two dimensional array will be better at realistic painting that people who can't, and that it will be very hard to find someone who is good at realistic painting who can't see the world as a two dimensional array. An empirical question, test it if you like!

Mike J. said...

Mike J.=Mike Jacovides, incidentally.

Eric Schwitzgebel said...

Arnold: There's something I'm not getting about your example. Why do I see the same image? Because his description is so evocative?

Eric Schwitzgebel said...

Interesting suggestions, Mike!

On 1: Yes, that seems likely. The best case would be to solicit reports while the eyes are still saccading around naturally, but that's pretty difficult. The best I can confidently do is have them saccade around semi-naturally while avoiding landing within a few degrees of some external detail to which I am paying attention. In this case, my experience seems to be unclarity.

Your second suggestion also seems plausible to me -- rather in accord with Sean Kelly's view. The standard version of the 2D view, of course, is that we all experience things that way, even non-artists. One question is whether in shifting to a 2D array, we are really discoving something fundamentally important about our ordinary experience or whether it's more like being able to see how long it would take to rollerskate from one represented position in the visual field to another.

Arnold Trehub said...

Eric: "There's something I'm not getting about your example."

Your puzzlement is justified because, in your experience, if you look at a blank canvas you will see nothing more than a blank canvas. So let me introduce a slight modification to the situation I described earlier:

An artist stares at a canvas on an easel as you look over his shoulder. In the center of the canvas is a vertical slit in which a vertical array of dots, moving up and down, disappear, and then reappear, in periodic fashion. Suddenly, an image of a full two-dimensional object that was created in the brain of the artist distinctly appears to him to be on the canvas without his making a mark on it. He says that he sees the object right there in front of him, and you believe him because you see the object on the canvas just like the one he describes to you, even before he describes it to you.

How would Introspective Pessimism undercut the introspective report of both parties in this situation?

Eric Schwitzgebel said...

Arnold: I'm assuming the dots are the result monitor outputs from a computer screen hidden within the canvas, or something like that. If you're trying to suggest hallucination while avoiding the word "hallucination" to avoid begging some question, then let me know.

I'm inclined to think that in such a situation, I should probably believe that the artist is having some sort of visual or quasi-visual or imagistic experience of the sort he describes, since that seems the best explanation of our otherwise-rather-inexplicably convergent reports.

Arnold Trehub said...

Yes, both you and the artist have the same hallucination (there, I said it). The big question is why is this the case? And wouldn't you have to suspend your introspective pessimism in this case?

Eric Schwitzgebel said...

Arnold: Yes I would tentatively suspend it, for similar reasons as in my earlier reply. I'm not a blanket skeptic. I just think that we're wrong much more commonly and much more severely than most people tend to think.