Seeing Red? You're Welcome!

The white fluorescent or LED lighting in your living room and kitchen are designed to make things look “natural” – that is, the way they might look in daylight. But – anecdotally at least – consumers don’t tend to like the fluorescent and LED lighting choices that are currently on the market. Why not? For some people, at least, it may have to do with the dullness of colors within that light.

If you’ve ever played with a prism, you know that white light is made up of many different colors shining together. One kind of light can make a perfectly good sandwich look like garbage, if the reds and greens of the tomato and lettuce are washed out. Or, if the light contains too much red, that juicy tomato might look about as tasty as a plastic toy.

To hit the “sweet spot” between too dull and too vivid, lighting companies rely on an international scoring system called the Color Rendering Index (CRI). A perfect score on the CRI is 100.

The trouble is, people seem to prefer lights with slightly lower scores than 100.

What’s going on? NIST researchers wondered whether consumers might prefer more vivid colors of light than the CRI calls for, so they conducted an experiment. There is a small room at NIST with an LED panel in the ceiling, which allows the scientists to control the overhead lighting. During the experiment, each test subject sat on a sofa in the room and looked at plates of fruit and vegetables on a table, as well as their own faces in a mirror. They were shown pairs of different kinds of white light, one after the other, and asked which one they “preferred.”

The researchers found that most test subjects vastly preferred white light that had more vivid reds in it than the light that currently gets the highest scores on the CRI. People also preferred a large bump in the vividness of green light, though they seemed to be most sensitive to changes in red.

After continuing these experiments with different colors, scientists hope to use the information to make new standards that take people’s preferences into account – so that your LED lamps, at least, will provide a “natural” as well as more pleasing illumination for your indoor tie-choosing, lipstick-applying, and sandwich-making needs.