Sorry, maybe the broad use of 'prefers' was poor wording on my part, of course the human eye can't subjectively prefer something. However, it is more sensitive to detail and attention is easier to maintain with low CCT at low light levels and vice versa for high light levels. This effect is often also evident in the general rating of light 'pleasantness'. Below is a quote from a (partially) relevant source found in a quick Google search on the subject.
'In 1941, a Dutch researcher, A.A. Kruithof ("Tubular Luminescence Lamps for General Illumination," Philips Technical Review, vol.6, 65-96, 1941), published a graph (see illustration) summarizing the relationship between color temperature, intensity, and the "pleasant" quality of an illumination source. According to the Kruithof curve, an observer prefers lower color temperature lighting when the light level is lower, and prefers a higher color temperature when the light level is higher. In essence, Kruithof provided a quantitative basis for describing a phenomenon that we all experience. For example, a space uniformly illuminated at 20 footcandles by daylight at a color temperature above 6000° K appears gloomy and overcast, whereas the same space illuminated at the same 20 footcandles with tungsten-halogen lamps at 3000° K appears pleasant and comfortable. The conclusion drawn from Kruithof's curve is that our color-temperature preference changes based on the intensity of the light within a space.'
Bold added by me. Perhaps this does not in actuality apply to each and every one of us, but as it is a generally accepted and widely tested and empirically supported effect I would expect (even if simply by the laws of statistics) if tested yourself for you to also experience the same 'tint preference shift' depending on level/intensity of light output.
Another quote from further down the same source. This is referring to the results of a more recent follow up study:
'The fact that most observers chose the same preferred color temperature within a narrow range is further evidence that the choice of color temperature involves more than an arbitrary aesthetic preference. It is based on a fundamental property of human vision. To further understand the preference for a specific color temperature, additional studies were undertaken in a non-art context. A white reflective surface was illuminated at a fixed intensity as the color temperature was increased and decreased in small increments between 3000° K and 4700° K. Observers were asked to describe the light as warm, cool or intermediate. For a surface illuminated at 20 foot candles, a value around 3700° K was chosen as the intermediate value, measured with a Minolta photographic color temperature meter (Model II). At 20 foot candles, 3700° K appears as an achromatic white light compared to higher or lower color temperature sources. Coincidentally, the choice of 3700° K was the preferred color temperature chosen on aesthetic grounds when looking at paintings. This suggests that the aesthetic preference for a specific color temperature derives from a fundamental characteristic of human color perception.'
But I'm not sure it's possible with a single LED at the current technology level, maybe for massive LED arrays..
