Relative colour cues improve colour constancy in birds (original) (raw)

2017, The Journal of Experimental Biology

A ripe strawberry looks red to our eyes in sunlight and in the green light of a forest, although the spectrum of light reflected from its surface differs dramatically. This is caused by two effects, colour constancy, and our ability to learn relative colour cues: the ripe strawberry remains relatively "redder" than an unripe green strawberry. While colour constancy - the ability to recognize colours in shifted illumination - has been studied in many animals, the use of relative colour cues is investigated more rarely. In a previous study on chickens, we measured how large illumination shifts their colour constancy mechanisms tolerate without reliable relative colour cues. Here, we show that chickens remain colour-constant over larger illumination shifts, if they can use such relative colour cues. As relative colour cues are readily available in natural environments, we suggest that their use contributes strongly to colour constancy performance in nature.

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

Proceedings. Biological sciences, 2016

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 da...

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Colour preferences and colour vision in poultry chicks

Proceedings of the Royal Society B: Biological Sciences, 2007

The dramatic colours of biological communication signals raise questions about how animals perceive suprathreshold colour differences, and there are long-standing questions about colour preferences and colour categorization by non-human species. This study investigates preferences of foraging poultry chicks (Gallus gallus) as they peck at coloured objects. Work on colour recognition often deals with responses to monochromatic lights and how animals divide the spectrum. We used complementary colours, where the intermediate is grey, and related the chicks' choices to three models of the factors that may affect the attractiveness. Two models assume that attractiveness is determined by a metric based on the colour discrimination threshold either (i) by chromatic contrast against the background or (ii) relative to an internal standard. An alternative third model is that categorization is important. We tested newly hatched and 9-day-old chicks with four pairs of (avian) complementary ...

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Novel Colours In Animal Perception

Other animals have colour experiences that are different from those of humans. I argue that they experience different colours. How can this be? I show by comparison to the case of auditory pitch and volume that colour vision is relatively unconstrained with regard to what it picks up.

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Inter-species variation in colour perception

Philosophical studies, 2009

Inter-species variation in colour perception poses a well known problem for the view that colours are mind-independent properties. Given that colour perception varies so drastically across species, which species perceive colours as they really are? I argue that all do. Specifically, members of different species perceive properties that are determinates of different, mutually compatible, determinables. This is an instance of the general ‘selectionist’ strategy for dealing with perceptual variation: objects simultaneously instantiate a plurality of mind-independent colours, and subjects select from amongst this plurality which colours they perceive.

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