Colorblind Synesthete experiences colors his eyes can’t see.
Synesthesia is a neurological condition where a certain sensory experience is mapped or overlaid with another sense. The most common form of this is Grapheme (numbers or letters) to color synesthesia. What's really interesting is most synesthetes can easily differentiate a grapheme's actual color from it's "synthetic" color. This all gets really weird when you get a synesthete who is colorblind. He sees colors in his mind that his eyes are physically unable to detect.
In a more generally comment about all this interesting research, we seem to be learning more and more about how the mind works, when just a few decades ago it really seemed like a black box. We could send stimuli in, and get responses out, but opening the box to see how it works made it stop working. While previously needed someone to be brain damaged in a very specific way to determine what a section of the brain did, Now the amazing detail they are coaxing out of various brain imaging methods combined with the ability to stimulate the brain directly without opening up the skull, it really seems some huge breakthroughs are in the pipe.