The Experts below are selected from a list of 16077 Experts worldwide ranked by ideXlab platform
Andrew C Smith - One of the best experts on this subject based on the ideXlab platform.
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effect of Colour Vision status on insect prey capture efficiency of captive and wild tamarins saguinus spp
Animal Behaviour, 2012Co-Authors: Andrew C Smith, Alison K Surridge, Mark J Prescott, Daniel Osorio, Nicholas I Mundy, Hannah M BuchanansmithAbstract:The Colour Vision polymorphism of most New World primates is a model system to study the function of Colour Vision. Theories for the evolution of primate trichromacy focus on the efficient detection and selection of ripe fruits and young leaves among mature leaves, when trichromats are likely to be better than dichromats. We examined whether Colour Vision status affected insect capture in groups of tamarins (Saguinus spp.) in captivity and in the field. Trichromatic tamarins caught more prey than dichromats, but dichromats caught a greater proportion of camouflaged prey than trichromats. The prey caught did not differ in size between the two visual phenotypes. Thus two factors may contribute to the maintenance of the genetic polymorphism of middle- to long-wavelength photopigments in platyrrhines: the advantage in finding fruit and leaves, which supports the maintenance of the polymorphism through a heterozygote advantage, and the dichromats’ exploitation of different (e.g. camouflaged) food, which results in frequency-dependent selection on the different Colour Vision phenotypes.
Daniel Osorio - One of the best experts on this subject based on the ideXlab platform.
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An Ishihara-style test of animal Colour Vision
The Journal of Experimental Biology, 2019Co-Authors: Karen L. Cheney, Daniel Osorio, Misha Vorobyev, Naomi F. Green, Alexander P. Vibert, N. Justin Marshall, John A. EndlerAbstract:ABSTRACT Colour Vision mediates ecologically relevant tasks for many animals, such as mate choice, foraging and predator avoidance. However, our understanding of animal Colour perception is largely derived from human psychophysics, and behavioural tests of non-human animals are required to understand how Colour signals are perceived. Here, we introduce a novel test of Colour Vision in animals inspired by the Ishihara Colour charts, which are widely used to identify human Colour deficiencies. In our method, distractor dots have a fixed chromaticity (hue and saturation) but vary in luminance. Animals can be trained to find single target dots that differ from distractor dots in chromaticity. We provide MATLAB code for creating these stimuli, which can be modified for use with different animals. We demonstrate the success of this method with triggerfish, Rhinecanthus aculeatus , which quickly learnt to select target dots that differed from distractor dots, and highlight behavioural parameters that can be measured, including success of finding the target dot, time to detection and error rate. We calculated discrimination thresholds by testing whether target Colours that were of increasing Colour distances (Δ S ) from distractor dots could be detected, and calculated discrimination thresholds in different directions of Colour space. At least for some Colours, thresholds indicated better discrimination than expected from the receptor noise limited (RNL) model assuming 5% Weber fraction for the long-wavelength cone. This methodology could be used with other animals to address questions such as luminance thresholds, sensory bias, effects of sensory noise, Colour categorization and saliency.
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An Ishihara-style test of animal Colour Vision
bioRxiv, 2018Co-Authors: Karen L. Cheney, Daniel Osorio, Misha Vorobyev, Naomi F. Green, Alexander P. Vibert, N. Justin Marshall, John A. EndlerAbstract:Abstract Colour Vision mediates ecologically relevant tasks for many animals, such as mate choice, foraging and predator avoidance. However, our understanding of animal Colour perception is largely derived from human psychophysics, even though animal visual systems differ from our own. Behavioural tests of non-human animals are required to understand how Colour signals are perceived by them. Here we introduce a novel test of Colour Vision in animals inspired by the Ishihara Colour charts, which are widely used to identify human Colour deficiencies. These charts consist of dots that vary in Colour, brightness and size, and are designed so that a numeral or letter is distinguishable from distractor dots for humans with normal Colour Vision. In our method, distractor dots have a fixed chromaticity (hue and saturation) but vary in luminance. Animals can be trained to find single target dots that differ from distractor dots in chromaticity. We provide Matlab code for creating these stimuli, which can be modified for use with different animals. We demonstrate the success of this method with triggerfish, Rhinecanthus aculeatus, and highlight behavioural parameters that can be measured, including success of finding the target dot, time to detect dot and error rate. Triggerfish quickly learnt to select target dots that differed from distractors dots regardless of the particular hue or saturation, and proved to use acute Colour Vision. We measured discrimination thresholds by testing the detection of target Colours that were of increasing Colour distances (ΔS) from distractor dots in different directions of Colour space. At least for some Colours, thresholds indicated better discrimination than expected from the Receptor Noise Limited (RNL) model assuming 5% Weber fraction for the long-wavelength cone. This methodology seems to be highly effective because it resembles natural foraging behavior for the triggerfish and may well be adaptable to a range of other animals, including mammals, birds, bees and freshwater fish. Other questions may be addressed using this methodology, including luminance thresholds, sensory bias, effects of sensory noise in detection tasks, Colour categorization and saliency.
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effect of Colour Vision status on insect prey capture efficiency of captive and wild tamarins saguinus spp
Animal Behaviour, 2012Co-Authors: Andrew C Smith, Alison K Surridge, Mark J Prescott, Daniel Osorio, Nicholas I Mundy, Hannah M BuchanansmithAbstract:The Colour Vision polymorphism of most New World primates is a model system to study the function of Colour Vision. Theories for the evolution of primate trichromacy focus on the efficient detection and selection of ripe fruits and young leaves among mature leaves, when trichromats are likely to be better than dichromats. We examined whether Colour Vision status affected insect capture in groups of tamarins (Saguinus spp.) in captivity and in the field. Trichromatic tamarins caught more prey than dichromats, but dichromats caught a greater proportion of camouflaged prey than trichromats. The prey caught did not differ in size between the two visual phenotypes. Thus two factors may contribute to the maintenance of the genetic polymorphism of middle- to long-wavelength photopigments in platyrrhines: the advantage in finding fruit and leaves, which supports the maintenance of the polymorphism through a heterozygote advantage, and the dichromats’ exploitation of different (e.g. camouflaged) food, which results in frequency-dependent selection on the different Colour Vision phenotypes.
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a review of the evolution of animal Colour Vision and visual communication signals
Vision Research, 2008Co-Authors: Daniel Osorio, Misha VorobyevAbstract:The visual displays of animals and plants are often Colourful, and Colour Vision allows animals to respond to these signals as they forage for food, choose mates and so-forth. This article discusses the evolutionary relationship between photoreceptor spectral sensitivities of four groups of land animals--birds, butterflies, primates and hymenopteran insects (bees and wasps)--, the Colour signals that are relevant to them, and how understanding is informed by models of spectral coding and Colour Vision. Although the spectral sensitivities of photoreceptors are known to vary adaptively under natural selection there is little evidence that those of hymenopterans, birds and primates are specifically adapted to the reflectance spectra of food plants or animal visual signals. On the other hand, the Colours of fruit, flowers and feathers may have evolved to be more discriminable for the Colour Vision of their natural receivers than for other groups of animals. Butterflies are unusual in that they have enjoyed a major radiation in receptor numbers and spectral sensitivities. The reasons for the radiation and diversity of butterfly Colour Vision remain unknown, but may include their need to find food plants and to select mates.
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effect of polymorphic Colour Vision for fruit detection in the spider monkey ateles geoffroyi and its implications for the maintenance of polymorphic Colour Vision in platyrrhine monkeys
The Journal of Experimental Biology, 2004Co-Authors: Pablo Ribahernandez, Kathryn E Stoner, Daniel OsorioAbstract:Most platyrrhine monkeys have an X-linked tri-allelic polymorphism for medium and long wavelength (M/L) sensitive cone photopigments. These pigments' sensitivity maxima (λmax) range from 535 to 562 nm. All animals also have an autosomally coded short-wavelength-sensitive (S) cone pigment. In populations with three M/L alleles there are six different Colour Vision phenotypes. Heterozygous females have trichromatic Colour Vision, while males and homozygous females are dichromats. The selective basis for this polymorphism is not understood, but is probably affected by the costs and benefits of trichromatic compared to dichromatic Colour Vision. For example, it has been suggested that trichromats are better equipped than dichromats to detect fruit against a leaf background. To investigate this possibility, we modeled fruit detection by various Colour Vision phenotypes present in the frugivorous spider monkey, Ateles geoffroyi. Our study population is thought to have three M/L alleles with cone pigment λmax values close to 535, 550 and 562 nm. The model predicted that all trichromat phenotypes had an advantage over dichromats, and the 535/562 nm phenotype was best; however, the model predicted that dichromats could detect all of the fruit species consumed by spider monkeys. We conclude that the heterozygote advantage experienced by females may be the most plausible explanation for the maintenance of this polymorphism in A. geoffroyi. Nevertheless, more studies need to evaluate social foraging behaviour and the performance of different phenotypes of other New World monkeys to determine if this is a global explanation for this phenomena or more specific to A. geofforyi.
Hannah M Buchanansmith - One of the best experts on this subject based on the ideXlab platform.
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effect of Colour Vision status on insect prey capture efficiency of captive and wild tamarins saguinus spp
Animal Behaviour, 2012Co-Authors: Andrew C Smith, Alison K Surridge, Mark J Prescott, Daniel Osorio, Nicholas I Mundy, Hannah M BuchanansmithAbstract:The Colour Vision polymorphism of most New World primates is a model system to study the function of Colour Vision. Theories for the evolution of primate trichromacy focus on the efficient detection and selection of ripe fruits and young leaves among mature leaves, when trichromats are likely to be better than dichromats. We examined whether Colour Vision status affected insect capture in groups of tamarins (Saguinus spp.) in captivity and in the field. Trichromatic tamarins caught more prey than dichromats, but dichromats caught a greater proportion of camouflaged prey than trichromats. The prey caught did not differ in size between the two visual phenotypes. Thus two factors may contribute to the maintenance of the genetic polymorphism of middle- to long-wavelength photopigments in platyrrhines: the advantage in finding fruit and leaves, which supports the maintenance of the polymorphism through a heterozygote advantage, and the dichromats’ exploitation of different (e.g. camouflaged) food, which results in frequency-dependent selection on the different Colour Vision phenotypes.
J A B Spalding - One of the best experts on this subject based on the ideXlab platform.
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medical students and congenital Colour Vision deficiency unnoticed problems and the case for screening
Occupational Medicine, 1999Co-Authors: J A B SpaldingAbstract:The results are given of a questionnaire study to determine the range of difficulties that doctors notice in their work due to congenital Colour Vision deficiency (CCVD). The study is primarily qualitative. A questionnaire was sent to 40 self-selected doctors, 35 of whom were general practitioners (GPs). All were administered a number of Colour Vision tests to assess the type and severity of their deficiency. Many difficulties and some ways of overcoming them were reported. Those with a mild deficiency reported fewer difficulties and this relationship was significant. Twenty-three of the doctors also reported difficulties as medical students and their answers are given verbatim. The results are discussed in relation to other studies and data on Colour Vision. The reasons for and against screening medical students for this deficiency are considered and it is concluded that there is a strong case for screening.
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doctors with inherited Colour Vision deficiency their difficulties in clinical work
1997Co-Authors: J A B SpaldingAbstract:The range of difficulties in clinical practice of doctors – mainly GPs – with inherited Colour Vision deficiency was determined by questionnaire and related to results of Colour Vision testing for type and severity. Many difficulties were found, more amongst those with moderate or severe defects, and doctors’ attitudes to their own Colour deficiencies varied. Vocational screening and counselling for prospective doctors should be considered.
Almut Kelber - One of the best experts on this subject based on the ideXlab platform.
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bird Colour Vision from cones to perception
Current opinion in behavioral sciences, 2019Co-Authors: Almut KelberAbstract:Birds use spectral information for circadian control, magnetic orientation and phototaxis but most importantly for discriminating the Colours of important objects such as food items or mates. Their tetrachromatic Colour Vision is based on four types of single cones expressing four opsin-based visual pigments and fine-tuned by the carotenoid composition in cone oil droplets. Bird Colour Vision is not as uniform as previously thought, and single visual pigments have been lost in several bird lineages. Diurnal birds have fine Colour discrimination and good Colour constancy but can generalize over similar though discriminable Colours. Bird Colour discrimination is ultimately limited by receptor noise but can be impaired in natural conditions, depending on light intensity and background coloration.
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Limits of Colour Vision in dim light.
Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 2010Co-Authors: Almut Kelber, Olle LindAbstract:Humans and most vertebrates have duplex retinae with multiple cone types for Colour Vision in bright light, and one single rod type for achromatic Vision in dim light. Instead of comparing signals from multiple spectral types of photoreceptors, such species use one highly sensitive receptor type thus improving the signal-to-noise ratio at night. However, the nocturnal hawkmoth Deilephila elpenor, the nocturnal bee Xylocopa tranquebarica and the nocturnal gecko Tarentola chazaliae can discriminate Colours at extremely dim light intensities. To be able to do so, they sacrifice spatial and temporal resolution in favour of Colour Vision. We review what is known about Colour Vision in dim light, and compare Colour Vision thresholds with the optical sensitivity of the photoreceptors in selected animal species with lens and compound eyes.
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the intensity threshold of Colour Vision in two species of parrot
The Journal of Experimental Biology, 2009Co-Authors: Olle Lind, Almut KelberAbstract:We have used behavioural tests to determine the intensity thresholds of Colour Vision in Bourke's parrots (Neopsephotus bourkii) and budgerigars (Melopsittacus undulatus). We have also examined the relationship between these thresholds and the optical sensitivities of single photoreceptors using morphological methods. Bourke's parrots lose Colour Vision in brighter light (0.4 cd m(-2)) than budgerigars (0.1 cd m(-2)) and both birds lose Colour Vision in brighter light ('end of civil twilight') than humans (0.02 cd m(-2),. moonlight'). The optical sensitivities of single cones are similar in both birds (budgerigar 0.27 mu m(2) sr, Bourke's parrot 0.25 mu m(2)sr) but Bourke's parrots have more (cone to rod ratio, 1.2:1.0), thinner (2.8 mu m) and longer rods (18.5 mu m) than budgerigars (2.1:1.0, 3.4 mu m, 13.3 mu m). Bourke's parrots thus have an eye type that, with a flexible pooling mechanism, allows for high resolution or high absolute sensitivity depending on the light conditions. The results nicely agree with the activity patterns of the birds, Bourke's parrots being active during the day and in twilight while budgerigars are not normally active before sunrise and after sunset. However, Bourke's parrots have fewer cones than budgerigars, which implies that a smaller number of cones are pooled within each retinal integration area. That could explain why Bourke's parrots have a higher intensity threshold of Colour Vision than budgerigars. Furthermore, the study emphasises the need to expand the sensitivity measure so that photoreceptor integration units are used rather than single receptors. (Less)
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animal Colour Vision behavioural tests and physiological concepts
Biological Reviews, 2003Co-Authors: Almut Kelber, Misha Vorobyev, Daniel OsorioAbstract:Over a century ago workers such as J. Lubbock and K. von Frisch developed behavioural criteria for establishing that non-human animals see Colour. Many animals in most phyla have since then been shown to have Colour Vision. Colour is used for specific behaviours, such as phototaxis and object recognition, while other behaviours such as motion detection are Colour blind. Having established the existence of Colour Vision, research focussed on the question of how many spectral types of photoreceptors are involved. Recently, data on photoreceptor spectral sensitivities have been combined with behavioural experiments and physiological models to study systematically the next logical question: 'what neural interactions underlie Colour Vision?' This review gives an overview of the methods used to study animal Colour Vision, and discusses how quantitative modelling can suggest how photoreceptor signals are combined and compared to allow for the discrimination of biologically relevant stimuli.
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polarisation dependent Colour Vision in papilio butterflies
The Journal of Experimental Biology, 2001Co-Authors: Almut Kelber, Christel Thunell, Kentaro ArikawaAbstract:Butterflies of the genus Papilio have polarisation-sensitive photoreceptors in all regions of the eye, and different spectral types of receptor are sensitive to different e-vector orientations. We have studied the consequences of this eye design for Colour Vision in behavioural tests and find that Papilio spp. see false Colours due to the polarisation of light. They discriminate between vertically and horizontally polarised light of the same Colour in the contexts of oviposition and feeding. The discrimination depends on the spectral composition of the stimuli. In the blue and probably in the green range, discrimination does not depend on intensity. However, Colour discrimination is influenced by polarisation. Thus, Colour and polarisation processing are not separated in the visual system of Papilio spp. From these results, we propose hypotheses about which photoreceptors contribute to Colour Vision in Papilio spp. and what adaptational value such a system might have for the butterflies. Finally, we give examples for other eyes that have a similar structure.
