Color Blindness Research Today is a free monthly online journal that collates and summarizes the latest research about Color Blindness, including details on causes, classification, red-green and blue-yellow color blindness, diagnosis.

Nocturnal colour vision--not as rare as we might think.

Kelber A, Roth LS

Department of Cell and Organism Biology, Vision Group, Lund University, Helgonavägen 3, S-22362 Lund, Sweden. almut.kelber@cob.lu.se

The dual retina of humans and most vertebrates consists of multiple types of cone for colour vision in bright light and one single type of rod, leaving these animals colour-blind at night. Instead of comparing the signals from different spectral types of photoreceptors, they use one highly sensitive receptor, thus improving the signal-to-noise ratio. However, nocturnal moths and geckos can discriminate colours at extremely dim light intensities when humans are colour-blind, by sacrificing spatial and temporal rather than spectral resolution. The advantages of colour vision are just as obvious at night as they are during the day. Colour vision is much more reliable than achromatic contrast, not only under changing light intensities, but also under the colour changes occurring during dusk and dawn. It can be expected that nocturnal animals other than moths and geckos make use of the highly reliable colour signals in dim light.

Published 16 February 2006 in J Exp Biol, 209: 781-8.
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