Research examines chickens perception of colour
Chickens can find the correct colour in redder lighting conditions, researchers from Lund University and the University of Bristol have found.
Their study indicates that – like humans – chickens have colour constancy, a feature of the colour perception system which ensures that the perceived colour of objects remains relatively constant under varying illumination conditions.
Peter Olsson and Professor Almut Kelber of Lund University, in collaboration with Dr David Wilby from the Ecology of Vision Group in Bristol's School of Biological Sciences, led the investigation.
Testing in different lighting conditions
The birds easily learned under white light to choose a food container of a specific orange colour and to avoid food containers with a yellow or red colour. The researchers found that the chickens could easily find the correct colour in redder illuminations, meaning that they do have colour constancy, just like humans.
The birds could recognise the correct orange colour in more strongly changed illuminations if the difference between the orange and the yellow and red colour was also more pronounced. However, their colour constancy was not perfect.
Comparison to chicken ancestral behaviour
In an analysis of their experiments, the scientists compared the amount of illumination change in which the chickens remained colour constant to the changes between forest light and daylight, which the chickens' Red Junglefowl ancestors would have experienced in their natural environment.
The chickens in the experiment remained colour constant in larger illumination changes than they would experience in their natural environment. Chickens, and very likely other birds as well, can thereby rely on their colour vision in the different environments they move between to find and identify food and mates.
The paper 'Quantitative studies of animal colour constancy: using the chicken as model' by Peter Olsson, David Wilby and Almut Kelber has been published in Proceedings of the Royal Society of London B.
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