Open AccessChicken colour discrimination depends on background colour
Author(s) -
Peter Olsson,
Robin D. Johnsson,
James J. Foster,
John D. Kirwan,
Olle Lind,
Almut Kelber
Publication year - 2020
Publication title -
journal of experimental biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.367
H-Index - 185
eISSN - 1477-9145
pISSN - 0022-0949
DOI - 10.1242/jeb.209429
Subject(s) - psychometric function , stimulus (psychology) , psychophysics , detection threshold , orange (colour) , mathematics , biology , statistics , pattern recognition (psychology) , artificial intelligence , psychology , perception , cognitive psychology , computer science , real time computing , neuroscience , horticulture
How well can a bird discriminate between two red berries on a green background? The absolute threshold of colour discrimination is set by photoreceptor noise, but animals do not perform at this threshold; their performance can depend on additional factors. In humans and zebra finches, discrimination thresholds for colour stimuli depend on background colour, and thus the adaptive state of the visual system. We have tested how well chickens can discriminate shades of orange or green presented on orange or green backgrounds. Chickens discriminated slightly smaller colour differences between two stimuli presented on a similarly coloured background, compared to a background of very different colour. The slope of the psychometric function is steeper when stimulus and background colours are similar but shallower when they differ markedly, indicating that background colour affects the certainty with which the animals discriminate the colours. The effect we find for chickens is smaller than that shown for zebra finches. We modelled the response to stimuli using Bayesian and maximum likelihood estimation (MLE) and implemented the psychometric function to estimate the effect size. We found that the result is independent of the psychophysical method used to evaluate the effect of experimental conditions on choice performance.