On the other hand, some people are very sensitive to color. Scientists call this phenomenon as tetromromatic because it can see four colors - not three. Birds and reptiles are classified as tetrachromatic, and this allows them to look into the infrared and ultraviolet spectra. The tetrachromatic man can not see beyond the seemingly normal-looking light spectrum, but has the most sensitive photoreceptor of color in red and green scales, making them more sensitive to all colors for normal humans. For these people, other people are the "color blind", because most people will not be able to ease easily in the summer and green that is common in Spain. As for a tetromromatic it will be obvious. So yes, if we both see the sunset, maybe I see something you can not see, or you see something I can not see.