I'm reading up a bit on consciousness and subjectivity, as this seems to be one of the biggest stumbling blocks for AI. A 'quick' browse of Wikipedia led me to the Mary's Room thought experiment (http://en.wikipedia.org/wiki/Mary%27s_room).
First, is it possible to grow up in a monochrome environment? Couldn't Mary look at her own body for examples of color? Second, would her nervous system still be able to perceive color after so long without it? If a person lives in a cave for a long time, they will emerge blind. Third, even if there is a difference, wouldn't that simply mean that there are at least tow different types of knowledge: objective and subjective? Objective knowledge would be that which does not require personal experience. Subjective knowledge would require the perception of a mind. Fourth, would we experience the same thing as Mary? If she saw a red apple, and we saw a read apple, are we seeing the same red? Maybe I'm seeing what Mary would call yellow. But as long as we are internally consistent and call the colors by the same name, we would never know. Subjectively, we could never truly describe what color we were actually seeing to the other.
The first and second questions lead me to wonder if this is even a valid thought experiment. The third breaks knowledge into qualia and not-qualia. The fourth leads us to physicalism and tells us that the qualia are nothing more that how our brains interpret a scene.