Colors are powerful. You can have the blues, see red, or feel green with jealousy.
Colors can feel like perfect representation of emotions. What if it could work the other way? What if just looking at a certain color could effect your mood? And what if one special shade could even overpower you, could cause actual physical weakness in anyone who looked at it?
One scientist in the 1970s tried to answer exactly this question starting with a drunk tank in a naval prison in Seattle. The results of this study, scientific or not, are still changing wall colors and possibly moods in prisons all over the world.