Chromatic and achromatic vision: parameter choice and limitations for reliable model predictions

  title={Chromatic and achromatic vision: parameter choice and limitations for reliable model predictions},
  author={Peter Olsson and Olle Lind and Almut Kelber},
  journal={Behavioral Ecology},
Many animals use vision to detect, discriminate, or recognize important objects such as prey, predators, homes, or mates. These objects may differ in color and brightness-having chromatic and achromatic contrast to the background or to other objects. Visual models are powerful tools to investigate contrast detection, but need to be calibrated by experimental data to provide robust predictions. The most critical parameter of current models-receptor noise-is usually estimated from a small number… 

High resolution of colour vision, but low contrast sensitivity in a diurnal raptor

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It is confirmed that luminance contrast discrimination thresholds are context-dependent and should therefore be interpreted with caution, and the RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law.

More than noise: context-dependent luminance contrast discrimination in a coral reef fish (Rhinecanthus aculeatus)

Analysis of luminance detection thresholds of triggerfish (Rhinecanthus aculeatus) reveals that the receptor noise limited (RNL) model needs to be used with caution in an achromatic context, confirming that luminance contrast discrimination thresholds are context dependent and should therefore be interpreted with caution.

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A new formulation is provided that accommodates and extends models to any number of photoreceptor types, offers flexibility to build user‐defined models, and allows users to easily adjust chromaticity diagram sizes to account for changes when using different number of Photoreceptors.

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The limits of chromatic discrimination in Metriaclima benetos, a rock-dwelling cichlid from Lake Malawi, are demonstrated, for the first time, using behavioral experiments and visual modeling, and blue is most chromatically contrasting against yellows and space-light, which might be important for discriminating male nuptial colorations and detecting males against the background.

Do not be distracted by pretty colors: a comment on Olsson et al.

It is thus impossible to predict receptor noise from behavioral data; instead, noise must be measured with appropriate electrophysiological procedures, and the RNL model was originally introduced for determining color thresholds and not for calculating perceptual differences between easily distinguishable colors.

Flower signal variability overwhelms receptor-noise and requires plastic color learning in bees

Observed behavioral color discrimination functions considering the respective conditioning procedures closely matched the range of signal variability for both honeybees and bumblebees, showing that color vision in bees cannot be described by a single fixed value, and plasticity is a key component of bee foraging behavior in natural environments.

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Chickens discriminated slightly smaller colour differences between two stimuli presented on a similarly coloured background, compared with a background of very different colour, indicating that background colour affects the certainty with which the animals discriminate the colours.



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The capabilities of di- and trichromatic vision are compared, and why some animals have more than three spectral types of receptors are asked, and awareness of colour and colour qualia cannot be easily tested in animals.

Photoreceptor sectral sensitivities in terrestrial animals: adaptations for luminance and colour vision

This review outlines how eyes of terrestrial vertebrates and insects meet the competing requirements of coding both spatial and spectral information, and looks at spectral tuning and diversification among ‘long-wavelength’ receptors (sensitivity maxima at greater than 500 nm), which play a primary role in luminance vision.

Receptor noise as a determinant of colour thresholds

  • M. VorobyevD. Osorio
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 1998
Spectral sensitivities, measured under bright conditions, for di–, tri–, and tetrachromatic eyes from a range of animals can be modelled by assuming that thresholds are set by colour opponency mechanisms whose performance is limited by photoreceptor noise, the achromatic signal being disregarded.

Bird colour vision: behavioural thresholds reveal receptor noise

The results suggest that chickens use spatial pooling of cone outputs to mitigate photon-shot noise, and the lowest intensity at which chickens can discriminate colours is 0.025 and 0.08 cd m−2 for the orange and green series.

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The dual rod system of amphibians supports colour discrimination at the absolute visual threshold

Together, the results indicate that different pathways are involved in processing colour cues depending on the ecological relevance of this information for each task, and approaches theoretical limits set by photon fluctuations and intrinsic noise.

The spatial tuning of achromatic and chromatic vision in budgerigars.

The study determined the spatial contrast sensitivity to achromatic and isoluminant red-green and blue-green color gratings in budgerigars and demonstrated the importance of the spatial dimension of color vision; fine patterns remain unresolved even if they present large color contrasts.

Thresholds and noise limitations of colour vision in dim light

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Spatial contrast sensitivity of birds

Six species of birds that represent a range of visual adaptations to varying environments exhibited low CS relative to humans and most mammals, which suggests that low CS is a general characteristic of birds.

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  • G. FieldA. Sampath
  • Biology
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2017
This article describes behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold and considers mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise.