is the ability to see four basic colors in place of the standard three - red
. While the existance of Tetrachromatists has not been confirmed yet, Dr. Neitz and Dr. Jordan are both conducting studies and are trying to find people with this disorder
. Due to the genetics
of vision, these people must be female and chances are that their male children will be color-blind
Why is this so? The genes for green and red photopigments are found on the X chromosome, that for blue is located far off on another chromosome. Since men only have only one X chromosome, no error-checking occurs when the new X chromosome is created in the egg. Since the red and green pigments are located so proximally they somtimes cross over; some of the eggs are disadvantaged from the start. The X chromosome might lack either a red or green photopigment gene or have dual red/green photopigment genes - regardless, the male offspring is bound to be color-blind.
However, if the lucky sperm cell enriches the egg with another X chromosome and a phenomenon called X inactivation occurs, there is the possibility of a Tetrachromatist. Through X inactivation, all four pigment-genes would be activated and the woman would have receptors for Red, Green, Off-green (or Off-red) and blue color vision.
Jeremy Nathans, a pioneer in color-vision research at Johns Hopkins University School of Medicine postulates that the brain would be able to interpret the fourth signal without trouble and assign it a new 'color.' The true determining aspect for seeing the fourth color is the degree of seperation between the peak in sensitivity for the new pigment versus red or green - if the peaks are too close, the person might only see a different (although alien) shade of green or red. Possible advantages of this would include increased awareness of skin tones (see if a child is bleak or flushed, even to a small degree;) the universal knowledge of a fourth color could aid in categorization and general awareness - try to imagine life without one of the three primaries.
So there is a color we're not seeing. Has anyone else read up on this, could it be perceived through biochemical manipulation? Since all the actual interpretation and assigning of a color takes place in the mind, this should be possible... too bad they can't tell us what the new color looks like, this is slowly driving me insane =)