In a paper published in this month’s LEUKOS (the journal of the Illuminating Engineering Society of North America), Dr. Houser and company asked 39 non-colorblind subjects to sort five pieces of identical material based on whiteness, with each item containing a different concentration of FWAs.
Under a normal halogen light, the subjects were able to order the items from dullest to brightest without issue, accurately sorting them from lowest to highest concentration of FWAs. Under typical LED light, however, things fell apart: since the LEDs emit no ultraviolet light, the FWA effect disappears. The subjects were reduced to moving the samples around at random. Read more at Gizmodo.