Quantitative studies of animal colour constancy: using the chicken as model

Colour constancy is the capacity of visual systems to keep colour perception
constant despite changes in the illumination spectrum. Colour constancy has
been tested extensively in humans and has also been described in many
animals. In humans, colour constancy is often studied quantitatively, but
besides humans, this has only been done for the goldfish and the honeybee.
In this study, we quantified colour constancy in the chicken by training the
birds in a colour discrimination task and testing them in changed illumination
spectra to find the largest illumination change in which they were able
to remain colour-constant. We used the receptor noise limited model for
animal colour vision to quantify the illumination changes, and found that
colour constancy performance depended on the difference between the colours
used in the discrimination task, the training procedure and the time the
chickens were allowed to adapt to a new illumination before making a
choice. We analysed literature data on goldfish and honeybee colour constancy
with the same method and found that chickens can compensate for
larger illumination changes than both. We suggest that future studies on
colour constancy in non-human animals could use a similar approach to
allow for comparison between species and populations.