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?
Philosophical zombies are a matter of debate in the philosophical community. Start with the concept of a zombie, something that is dead inside, with no consciousness, just a mindless need to feed and a basic response to noise and movement. Now build it up a little. Maybe it shows minor instinctive responses in avoiding danger or getting around obstacles. Now perhaps it can make a few recognizable words, but they're just rote responses.
You get where this is going. Eventually, you can build a "zombie" up so it has no consciousness, but it physically responds the way a human does. It can hold a conversation, drive a car, do a job, and generally live out its days faking humanity. This is a philosophical zombie. It makes us question if there is a difference, tangible or intangible, between a sophisticated response and actual awareness.
That might seem like a purely theoretical distinction, but scientists seem to have found a (very limited) philosophical zombie. Although the patient in question, was able to make the right responses, he had no consciousness of what he was responding to.
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?