A limited color vision philosophical zombie?

This article at IO9 reminded me of the recent discussion some of us had on philosophical zombies.

Ever heard of the philosophical zombie? It’s a philosophical concept that rarely translates into physiology – until now. A case of false color-blindness makes us wonder: What’s the difference between seeing something and knowing that you’re seeing something?

The patient in question was recovering from a stroke, and one of his complaints was a loss of color vision. His medical providers noticed he wasn’t making the same mistakes that many people with limited color vision do, and so they had him do a quick test. They showed different colors to him, and asked him to take a guess at what they were. He guessed right much of the time. They then asked how accurately he thought he was guessing. He gave an estimate of his accuracy, and that estimation shot up for the times when he guessed right.

So not only was this person seeing most colors, he knew, most of the time that he was seeing them. He just had no consciousness of the colors he was seeing. He was, in essence, a philosophical zombie when it came to color vision. Although he could behave as if he saw colors, he never, consciously did. So what do you think? Can you be a zombie, without anyone guessing that you are?

I don’t know if any of us would really be tempted to call this poor patient a p-zombie, but it does remind me of the attention schema theory of consciousness that sees it as basically a feedback mechanism, a way for the brain to summarize its current state (albeit incompletely and not always accurately) for use by the language center and other areas of the brain.

Viewed in that light, what’s damaged in this patient’s brain is probably the connection between the vision processing centers of their brain, and the module that summarizes the information.  So, they see color, but can’t consciously experience the color anymore.

One thing that I do find puzzling is that they can still articulate the color when pressed to make a best guess.  That means that there are enough connections to get the information to their language centers, but not necessarily through the consciousness centers.  That’s weird, but reminds me of other site blindness issues I’ve read about before.  These cases seem to imply that the language center isn’t totally dependent on consciousness.  (Which actually isn’t too surprising given how often I shoot my mouth off without thinking.)

5 thoughts on “A limited color vision philosophical zombie?

  1. Clearly color is spiritually visible, and while this man’s material brain couldn’t comprehend color due to injury, the immaterial soul was doing the job just fine.

    Or something.


  2. It’s not quite like the p-zombie because they are at least aware that something is wrong. Still, I’ve made an argument against qualia along lines that might be undermined by cases like this.

    Suppose you lose the mysterious qualia of colour but keep everything else, including the causal connections that lead to you correctly identifying colours etc. So you are a p-zombie with regard to colour alone. Would you notice anything was missing? I think not, because if all the functional aspect of colour perception is in tact, you will behave in exactly the same way. You will not be able to articulate what is missing, and you will think all the same thoughts. This leads me to suggest that qualia are logically necessary consequences of the functionality of perception. Without qualia, you would not be able to discriminate between green and red, because qualia are the only means by which the difference can be identified.

    Even in cases like this, and cases like blindsight, where the patient maintains there are no qualia, if they have the ability to make a guess then they are detecting something, some kind of internal hunch. This feeling could be conceived of as a quale, though perhaps a much less vivid one than they had experienced formerly.


    1. I think that’s right. There are actually cases where brain damaged people have their consciousness damaged in a way where they don’t notice any problem. One condition has people who can no longer perceive their left field of vision. They don’t notice that they can’t perceive their left field of vision anymore, the concept of a left field of vision becomes incomprehensible to them.

      There are also people who lose the ability to recognize faces, or their own body. They don’t always understand their limitation, except for when their friends and family tell them that they’re missing something. Even then, their understanding is only abstract.


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