I have always been fascinated by synesthesia, a physical phenomenon in which “stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway” (Wikipedia). Those who experience this phenomenon describe sensory conjunctions that suggest a strong parallel between seemingly disconnected senses; they can visualize particular shapes when tasting specific flavors or see color when listening to certain sounds.
The latter example came to my mind when reading about color compatibility in The Complete Color Harmony by Leatrice Eiseman.
According to Eiseman, the color wheel explains color compatibilities, which provide “standard harmonies of color.” One can look to these compatibilities, like monochrome, monochromatic, and analogous (among others), like guidelines for selecting colors to use together which will feel harmonious. Although one might deviate from these guidelines, it is most often done with strong intention to do so.
Like color compatibilities, musical scales provide guidelines by which musicians can select notes to “use together.” Whether major, melodic minor, or harmonic minor (or any of the forty-five other scales), the musician selects the scale which will serve as his or her “guideline.”
And so, the purpose of and application for color compatibilities and musical scales is quite similar. It seems that despite our differences, us humans have remarkably similar tastes across many senses. Just as a musician must select the scale (or combination of scales) for his or her masterpiece, the designer must select the color compatibilities for his or her design.
In applying this to my own experience as a designer: Stick to color conventions, but sometimes don’t. More seriously: Color conventions serve as wonderful, universal guidelines, and they should followed unless the intention of the design necessitates a deviation from the norm.