Psychologically pure colors are colors that exhibit a homogeneous appearance on some dimension of perceived color. Purity of appearance is closely tied up with theoretical understandings of the three canonical color attributes of hue, saturation, and lightness. According to the dominant Hering opponent color framework, the hues red, green, blue, and yellow are distinctive and fundamental to all...

When Matthew Blakeslee shapes hamburger patties with his hands, he experiences a vivid bitter taste in his mouth. Esmerelda Jones (a pseudonym) sees blue when she listens to the note C sharp played on the piano; other notes evoke different hues--so much so that the piano keys are actually color-coded, making it easier for her to remember and play musical scales. And when Jeff Coleman looks at p...