Puzzler...

Last week's puzzler had more wrong answers than I usually see – chaparral esoterica must not be the repertoire of most of my readers! But, having said that, I must also say that more than half (about 57%) of you got it right: chaparral plants are generally of uniform size because they're all about the same age. They're all the same age because many of the chaparral plants require fire for their seeds to germinate – so they all sprouted in the year or two following the last fire that burned over the area. In the case of Lawson Valley, where I live, that last happened in 1973.

This week's puzzler is on a technology phenomena. There are only a few choices of technology that can light your home in the absence of sunlight: flames (candles, gas lights), materials heated to incandescence (incandescent bulbs, halogen lamps), fluorescence (fluorescent lamps, CFLs), photonic emission from plasma (neon lamps), and light-emitting semiconductors (LED lamps). All of these technologies produce light, but the light produced is not all the same.

This is something anyone can readily observe, without any instruments: observe any ordinary, multi-colored object under the various kinds of lighting and they look different under each kind, even if the brightnesses are the same. Women know that their makeup looks different under incandescent lighting than it does under fluorescent lighting. Similarly, photographers and painters are picky about their lighting sources, because their subjects will look different under different kinds of lights.

When people can freely choose the type of lighting they want, without being constrained by cost or considerations of efficiency, they will almost always choose high-brightness incandescent lighting (such as halogen lamps). Several studies have tested thousands of subjects in side-by-side tests. The study that most impressed me put people in a room where light was “piped in” in such a way that they could not determine its source. The test subjects were given a switch and a dimmer control that let them choose between incadescent bulbs, halogen bulbs, CFLs, traditional fluorescent lamps, and LED lamps (though the test subjects didn't know which kind of lighting corresponded to which position of the switch). They were asked to choose the kind of lighting and the lighting level that they though was most pleasing. The room contained furniture, pictures on the wall, and a table full of magazines. Over 98% of the test subjects chose halogen lighting at within 10% of maximum brightness.

Here's the question: what exactly is it that makes one lighting technology more pleasing to the eye than another?