A1 Journal article (refereed)
Behavioural thresholds of blue tit colour vision and the effect of background chromatic complexity (2021)

Silvasti, S. A., Valkonen, J. K., & Nokelainen, O. (2021). Behavioural thresholds of blue tit colour vision and the effect of background chromatic complexity. Vision Research, 182, 46-57. https://doi.org/10.1016/j.visres.2020.11.013

JYU authors or editors

Publication details

All authors or editorsSilvasti, Sanni A.; Valkonen, Janne K.; Nokelainen, Ossi

Journal or seriesVision Research



Publication year2021


Pages range46-57


Publication countryUnited Kingdom

Publication languageEnglish


Publication open accessNot open

Publication channel open access

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/74297


Vision is a vital attribute to foraging, navigation, mate selection and social signalling in animals, which often have a very different colour perception in comparison to humans. For understanding how animal colour perception works, vision models provide the smallest colour difference that animals of a given species are assumed to detect. To determine the just-noticeable-difference, or JND, vision models use Weber fractions that set discrimination thresholds of a stimulus compared to its background. However, although vision models are widely used, they rely on assumptions of Weber fractions since the exact fractions are unknown for most species. Here, we test; i) which Weber fractions in long-, middle- and shortwave (i.e. L, M, S) colour channels best describe the blue tit (Cyanistes caeruleus) colour discrimination, ii) how changes in hue of saturated colours and iii) chromatic background noise impair search behaviour in blue tits. We show that the behaviourally verified Weber fractions on achromatic backgrounds were L: 0.05, M: 0.03 and S: 0.03, indicating a high colour sensitivity. In contrast, on saturated chromatic backgrounds, the correct Weber fractions were considerably higher for L: 0.20, M: 0.17 and S: 0.15, indicating a less detailed colour perception. Chromatic complexity of backgrounds affected the longwave channel, while middle- and shortwave channels were mostly unaffected. We caution that using a vision model whereby colour discrimination is determined in achromatic viewing conditions, as they often are, can lead to misleading interpretations of biological interactions in natural – colourful – environments.

Keywordsperception (activity)senseseyesightcolourssensory receptor cellsanimal behaviourblue tit

Free keywordsavian vision model; Cyanistes caeruleus; discrimination thresholds; pavo; receptor-noise; vision testing; Weber fraction

Contributing organizations

Ministry reportingYes

Reporting Year2021

JUFO rating1

Last updated on 2024-03-04 at 20:06