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Newman BA, D’Angelo GJ. A Review of Cervidae Visual Ecology. Animals (Basel) 2024; 14:420. [PMID: 38338063 PMCID: PMC10854973 DOI: 10.3390/ani14030420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/21/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
This review examines the visual systems of cervids in relation to their ability to meet their ecological needs and how their visual systems are specialized for particular tasks. Cervidae encompasses a diverse group of mammals that serve as important ecological drivers within their ecosystems. Despite evidence of highly specialized visual systems, a large portion of cervid research ignores or fails to consider the realities of cervid vision as it relates to their ecology. Failure to account for an animal's visual ecology during research can lead to unintentional biases and uninformed conclusions regarding the decision making and behaviors for a species or population. Our review addresses core behaviors and their interrelationship with cervid visual characteristics. Historically, the study of cervid visual characteristics has been restricted to specific areas of inquiry such as color vision and contains limited integration into broader ecological and behavioral research. The purpose of our review is to bridge these gaps by offering a comprehensive review of cervid visual ecology that emphasizes the interplay between the visual adaptations of cervids and their interactions with habitats and other species. Ultimately, a better understanding of cervid visual ecology allows researchers to gain deeper insights into their behavior and ecology, providing critical information for conservation and management efforts.
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Affiliation(s)
- Blaise A. Newman
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
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2
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Foster DH, Nascimento SM. Little information loss with red-green color deficient vision in natural environments. iScience 2023; 26:107421. [PMID: 37593460 PMCID: PMC10428128 DOI: 10.1016/j.isci.2023.107421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/10/2023] [Accepted: 07/13/2023] [Indexed: 08/19/2023] Open
Abstract
Inherited color vision deficiency affects red-green discrimination in about one in twelve men from European populations. Its effects have been studied mainly in primitive foraging but also in detecting blushing and breaking camouflage. Yet there is no obvious relationship between these specific tasks and vision in the real world. The aim here was to quantify the impact of color vision deficiency by estimating computationally the information available to observers about colored surfaces in natural scenes. With representative independent sets of 50 and 100 hyperspectral images, estimated information was found to be only a little less in red-green color vision deficiency than in normal trichromacy. Colorimetric analyses revealed the importance of large lightness variations within scenes, small redness-greenness variations, and uneven frequencies of different colored surfaces. While red-green color vision deficiency poses challenges in some tasks, it has much less effect on gaining information from natural environments.
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Affiliation(s)
- David H. Foster
- Department of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, UK
| | - Sérgio M.C. Nascimento
- Physics Center of Minho and Porto Universities (CF-UM-UP), University of Minho, 4710-057 Braga, Portugal
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3
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Martínez-Domingo MÁ, Galdón A, Gómez-Robledo L, Huertas R, Hernández-Andrés J, Valero EM. Color vision deficiencies and camouflage: a comparative study between normal and CVD observers. OPTICS EXPRESS 2022; 30:13699-13713. [PMID: 35472977 DOI: 10.1364/oe.451525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/19/2022] [Indexed: 06/14/2023]
Abstract
There is a belief that observers with color vision deficiencies (CVD) perform better in detecting camouflaged objects than normal observers. Some studies have concluded contradictory findings when studying the performance of normal and CVD observers in the camouflage detection tasks in different conditions. This work presents a literature review on this topic, dividing it into three different and contradictory types of results: better performance for CVD, for normal observers, or same performance. Besides, two psychophysical experiments have been designed and carried out in a calibrated computer monitor on both normal and CVD human observers to measure the searching times of the different types of observers needed to find camouflaged stimuli in two different types of stimuli. Results show the trend that, in our experimental conditions, normal observers need shorter searching times than CVD observers in finding camouflaged stimuli both in images of natural scenes and in images with synthetic stimuli.
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4
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Barros PKS, Castro FN, Pessoa DMA. Detection of conspicuous and cryptic food by common marmosets (Callithrix jacchus): An evaluation of the importance of color and shape cues. Behav Processes 2021; 192:104495. [PMID: 34487831 DOI: 10.1016/j.beproc.2021.104495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 08/21/2021] [Accepted: 09/01/2021] [Indexed: 11/25/2022]
Abstract
In primates, the advantage of trichromacy (i.e., color vision expressed by most humans) over dichromacy (i.e., color vision expressed by many colorblind humans) has been linked to the detection of yellowish/reddish targets against a background of mature green leaves. Nevertheless, mostly because of studies conducted in humans, we know that achromatic cues might also play an important role in object identification, particularly when camouflage is involved. For instance, dichromacy favors the detection of camouflaged targets by exploitation of shape cues. The present study sought to evaluate the relative importance of color and shape cues on the detection of food targets by female and male marmosets (Callithrix jacchus). Animals were observed with respect to their foraging behavior and the number of food targets captured. We confirmed that females are advantageous in detecting conspicuous food against a green background and revealed that females and males rely on shape cues to segregate cryptic food. Unexpectedly, males outperformed females in cryptic food foraging, while camouflage improved males' (but not females') performance. Here we show that dichromats could potentially benefit from a better segregation of green natural targets (e.g., immature fruits, green insects, and gum trees) when viewed against a green dappled background.
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Affiliation(s)
- Priscilla Kelly Silva Barros
- Laboratory of Sensory Ecology, Department of Physiology and Behavior, Biosciences Center, Federal University of Rio Grande do Norte, Natal, RN, 59072-970, Brazil; Primate Center, Department of Physiology and Behavior, Biosciences Center, Federal University of Rio Grande do Norte, Natal, RN, 59072-970, Brazil
| | - Felipe Nalon Castro
- Laboratory of Human Behavior Evolution, Department of Physiology and Behavior, Biosciences Center, Federal University of Rio Grande do Norte, Natal, RN, 59072-970, Brazil
| | - Daniel Marques Almeida Pessoa
- Laboratory of Sensory Ecology, Department of Physiology and Behavior, Biosciences Center, Federal University of Rio Grande do Norte, Natal, RN, 59072-970, Brazil; Primate Center, Department of Physiology and Behavior, Biosciences Center, Federal University of Rio Grande do Norte, Natal, RN, 59072-970, Brazil.
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5
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de Moraes PZ, Diniz P, Spyrides MHC, Pessoa DMA. The effect of pelage, background, and distance on predator detection and the evolution of primate color vision. Am J Primatol 2021; 83:e23230. [PMID: 33475188 DOI: 10.1002/ajp.23230] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 10/23/2020] [Accepted: 11/17/2020] [Indexed: 11/10/2022]
Abstract
Primates' predators, such as carnivore mammals, usually rely on camouflage to increase proximity to prey and start a predatory attempt. Camouflage depends not only on the color pattern presented by a predator's pelage but also on the background scene in which the hunting takes place. Another factor that influences camouflage effectiveness is prey's color vision since a given camouflage strategy might not work for all visual phenotypes. Still, little research has been made on the effect of primate visual phenotype on predator detection. Here, we investigate the effects of natural pelages, background scenarios, visual phenotypes, and detection distances on predator detection. We used photographs of taxidermized carnivores (ocelots, cougars, and lesser grisons) as detection stimuli, taken in three different natural scenarios (forest, savanna, and grassland), and at two viewing distances (near and far). On a touchscreen monitor, sets of four images (only one containing a hidden animal) were randomly presented to 39 human males (19 dichromats and 20 trichromats). We found that trichromats, when compared to dichromats, present a lower latency and a higher accuracy of carnivore detection for some conditions tested. We also found that pelage color, background scenario, and detection distance interact to influence the effectiveness of camouflage. Our results suggest that trichromacy might be even more advantageous for carnivore detection than thought before, since it facilitates detection of mammals with diverse pelage colorations, in environments with different phytophysiognomies, and at longer distances. We also propose that the higher rates of dichromacy found in modern human societies could have resulted from a relaxation in predation.
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Affiliation(s)
- Pedro Z de Moraes
- Laboratory of Sensory Ecology, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, 59078-970, Brazil
| | - Pedro Diniz
- Ecology Graduation Program, University of Brasilia, Brasilia, 70910-900, Brazil.,Laboratory of Animal Behavior, Department of Zoology, University of Brasilia, Brasilia, 70910-900, Brazil
| | - Maria Helena C Spyrides
- Department of Statistics, Federal University of Rio Grande do Norte, Natal, 59078-970, Brazil
| | - Daniel M A Pessoa
- Laboratory of Sensory Ecology, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, 59078-970, Brazil.,Primate Center, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, 59078-970, Brazil
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6
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Galloway JAM, Green SD, Stevens M, Kelley LA. Finding a signal hidden among noise: how can predators overcome camouflage strategies? Philos Trans R Soc Lond B Biol Sci 2020; 375:20190478. [PMID: 32420842 PMCID: PMC7331011 DOI: 10.1098/rstb.2019.0478] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Substantial progress has been made in the past 15 years regarding how prey use a variety of visual camouflage types to exploit both predator visual processing and cognition, including background matching, disruptive coloration, countershading and masquerade. By contrast, much less attention has been paid to how predators might overcome these defences. Such strategies include the evolution of more acute senses, the co-opting of other senses not targeted by camouflage, changes in cognition such as forming search images, and using behaviours that change the relationship between the cryptic individual and the environment or disturb prey and cause movement. Here, we evaluate the methods through which visual camouflage prevents detection and recognition, and discuss if and how predators might evolve, develop or learn counter-adaptations to overcome these. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- James A M Galloway
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Samuel D Green
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Laura A Kelley
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
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7
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Widayati KA. Color Perception in Protanomalous Female Macaca fascicularis. Iperception 2019; 10:2041669519846136. [PMID: 31066374 PMCID: PMC6488792 DOI: 10.1177/2041669519846136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 04/02/2019] [Indexed: 11/17/2022] Open
Abstract
Protanomalous females with X chromosome-linked color vision deficiency exhibit mild abnormalities, whereas dichromats show a distinct deficiency in discriminating certain color pairs. Dichromats have an advantage in detecting a textured target when it is camouflaged by red-green colors, owing to their insensitivity to these colors. However, it is not certain whether protanomalous females possess a similar advantage in breaking camouflage. Here, we introduce an animal model of dichromatic macaque monkeys and protanomalous females. We examined whether protanomalous females have the same advantage in breaking color camouflage as shown by dichromatic macaques. We also tested whether they could discriminate a certain color pair that trichromats could, where the dichromats are confused. Our experiments show that protanomalous macaques can break color camouflage, similar to dichromats, and can discriminate colors similarly to trichromats. Protanomalous females are thus thought to have the combined ecological advantages of being both trichromats and dichromats.
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8
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Doron R, Sterkin A, Fried M, Yehezkel O, Lev M, Belkin M, Rosner M, Solomon AS, Mandel Y, Polat U. Spatial visual function in anomalous trichromats: Is less more? PLoS One 2019; 14:e0209662. [PMID: 30673711 PMCID: PMC6343896 DOI: 10.1371/journal.pone.0209662] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 12/09/2018] [Indexed: 12/03/2022] Open
Abstract
Color deficiency is a common inherited disorder affecting 8% of Caucasian males with anomalous trichromacy (AT); it is the most common type of inherited color vision deficiency. Anomalous trichromacy is caused by alteration of one of the three cone-opsins’ spectral sensitivity; it is usually considered to impose marked limitations for daily life as well as for choice of occupation. Nevertheless, we show here that anomalous trichromat subjects have superior basic visual functions such as visual acuity (VA), contrast sensitivity (CS), and stereo acuity, compared with participants with normal color vision. Both contrast sensitivity and stereo acuity performance were correlated with the severity of color deficiency. We further show that subjects with anomalous trichromacy exhibit a better ability to detect objects camouflaged in natural gray scale figures. The advantages of color-deficient subjects in spatial vision performance could explain the relatively high prevalence of color-vision polymorphism in humans.
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Affiliation(s)
- Ravid Doron
- Department of Optometry and Vision Science, Hadassah Academic College, Jerusalem, Israel
| | - Anna Sterkin
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Moshe Fried
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Oren Yehezkel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Maria Lev
- The School of Optometry and Vision Science, The Mina & Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat-Gan, Israel
| | - Michael Belkin
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Mordechai Rosner
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Arieh S. Solomon
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Hashomer, Israel
| | - Yossi Mandel
- The School of Optometry and Vision Science, The Mina & Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat-Gan, Israel
- Bar-Ilan Institute for Nanotechnology and Advanced Material (BINA), Bar Ilan University, Ramat-Gan, Israel
- * E-mail: (UP); (YM)
| | - Uri Polat
- The School of Optometry and Vision Science, The Mina & Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat-Gan, Israel
- * E-mail: (UP); (YM)
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9
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Troscianko J, Wilson-Aggarwal J, Griffiths D, Spottiswoode CN, Stevens M. Relative advantages of dichromatic and trichromatic color vision in camouflage breaking. Behav Ecol 2017; 28:556-564. [PMID: 29622920 PMCID: PMC5873837 DOI: 10.1093/beheco/arw185] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 11/24/2016] [Accepted: 12/07/2016] [Indexed: 11/13/2022] Open
Abstract
There is huge diversity in visual systems and color discrimination abilities, thought to stem from an animal’s ecology and life history. Many primate species maintain a polymorphism in color vision, whereby most individuals are dichromats but some females are trichromats, implying that selection sometimes favors dichromatic vision. Detecting camouflaged prey is thought to be a task where dichromatic individuals could have an advantage. However, previous work either has not been able to disentangle camouflage detection from other ecological or social explanations, or did not use biologically relevant cryptic stimuli to test this hypothesis under controlled conditions. Here, we used online “citizen science” games to test how quickly humans could detect cryptic birds (incubating nightjars) and eggs (of nightjars, plovers and coursers) under trichromatic and simulated dichromatic viewing conditions. Trichromats had an overall advantage, although there were significant differences in performance between viewing conditions. When searching for consistently shaped and patterned adult nightjars, simulated dichromats were more heavily influenced by the degree of pattern difference than were trichromats, and were poorer at detecting prey with inferior pattern and luminance camouflage. When searching for clutches of eggs—which were more variable in appearance and shape than the adult nightjars—the simulated dichromats learnt to detect the clutches faster, but were less sensitive to subtle luminance differences. These results suggest there are substantial differences in the cues available under viewing conditions that simulate different receptor types, and that these interact with the scene in complex ways to affect camouflage breaking.
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Affiliation(s)
- Jolyon Troscianko
- University of Exeter, School of Biosciences, Penryn Campus, Penryn TR10 9FE, UK
| | | | - David Griffiths
- University of Exeter, School of Biosciences, Penryn Campus, Penryn TR10 9FE, UK.,FoAM - Kernow, Workshop E, Jubilee Warehouse, Commercial Road, Penryn TR10 8FG, UK
| | - Claire N Spottiswoode
- University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, UK, and.,DST-NRF Centre of Excellence at the FitzPatrick Institute, University of Cape Town, Rondebosch 7701, South Africa
| | - Martin Stevens
- University of Exeter, School of Biosciences, Penryn Campus, Penryn TR10 9FE, UK
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10
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Lišková S, Landová E, Frynta D. Human Preferences for Colorful Birds: Vivid Colors or Pattern? EVOLUTIONARY PSYCHOLOGY 2015. [DOI: 10.1177/147470491501300203] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In a previous study, we found that the shape of a bird, rather than its color, plays a major role in the determination of human preferences. Thus, in the present study, we asked whether the preferences of human respondents towards uniformly shaped, colorful birds are determined by pattern rather than color. The experimental stimuli were pictures of small passerine birds of the family Pittidae possessing uniform shape but vivid coloration. We asked 200 participants to rank 43 colored and 43 identical, but grayscaled, pictures of birds. To find the traits determining human preferences, we performed GLM analysis in which we tried to explain the mean preference ranks and PC axes by the following explanatory variables: the overall lightness and saturation, edges (pattern), and the portion of each of the basic color hues. The results showed that the mean preference ranks of the grayscale set is explained mostly by the birds' pattern, whereas the colored set ranking is mostly determined by the overall lightness. The effect of colors was weaker, but still significant, and revealed that people liked blue and green birds. We found no significant role of the color red, the perception of which was acquired relatively recently in evolution.
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Affiliation(s)
- Silvie Lišková
- National Institute of Mental Health, Klecany, Czech Republic
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University, Praha 2, Czech Republic; National Institute of Mental Health, Klecany, Czech Republic
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University, Praha 2, Czech Republic; National Institute of Mental Health, Klecany, Czech Republic
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11
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Tajima S, Komine K. Saliency-based color accessibility. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2015; 24:1115-1126. [PMID: 25608304 DOI: 10.1109/tip.2015.2393056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Perception of color varies markedly between individuals because of differential expression of photopigments in retinal cones. However, it has been difficult to quantify the individual cognitive variation in colored scene and to predict its complex impacts on the behaviors. We developed a method for quantifying and visualizing information loss and gain resulting from individual differences in spectral sensitivity based on visual salience. We first modeled the visual salience for color-deficient observers, and found that the predicted losses and gains in local image salience derived from normal and color-blind models were correlated with the subjective judgment of image saliency in psychophysical experiments, i.e., saliency loss predicted reduced image preference in color-deficient observers. Moreover,saliency-guided image manipulations sufficiently compensated for individual differences in saliency. This visual saliency approach allows for quantification of information extracted from complex visual scenes and can be used as an image compensation to enhance visual accessibility by color-deficient individuals.
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12
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Pessoa DMA, Maia R, de Albuquerque Ajuz RC, De Moraes PZPMR, Spyrides MHC, Pessoa VF. The adaptive value of primate color vision for predator detection. Am J Primatol 2014; 76:721-9. [PMID: 24535839 DOI: 10.1002/ajp.22264] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 12/13/2013] [Accepted: 12/15/2013] [Indexed: 11/09/2022]
Abstract
The complex evolution of primate color vision has puzzled biologists for decades. Primates are the only eutherian mammals that evolved an enhanced capacity for discriminating colors in the green-red part of the spectrum (trichromatism). However, while Old World primates present three types of cone pigments and are routinely trichromatic, most New World primates exhibit a color vision polymorphism, characterized by the occurrence of trichromatic and dichromatic females and obligatory dichromatic males. Even though this has stimulated a prolific line of inquiry, the selective forces and relative benefits influencing color vision evolution in primates are still under debate, with current explanations focusing almost exclusively at the advantages in finding food and detecting socio-sexual signals. Here, we evaluate a previously untested possibility, the adaptive value of primate color vision for predator detection. By combining color vision modeling data on New World and Old World primates, as well as behavioral information from human subjects, we demonstrate that primates exhibiting better color discrimination (trichromats) excel those displaying poorer color visions (dichromats) at detecting carnivoran predators against the green foliage background. The distribution of color vision found in extant anthropoid primates agrees with our results, and may be explained by the advantages of trichromats and dichromats in detecting predators and insects, respectively.
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Affiliation(s)
- Daniel Marques Almeida Pessoa
- Laboratory of Sensory Ecology, Department of Physiology, Federal University of Rio Grande do Norte, Natal, RN, Brazil; Laboratory for the Advanced Study of Primates, Department of Physiology, Federal University of Rio Grande do Norte, Natal, RN, Brazil
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13
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The influence of color on snake detection in visual search in human children. Sci Rep 2011; 1:80. [PMID: 22355599 PMCID: PMC3216567 DOI: 10.1038/srep00080] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 08/12/2011] [Indexed: 11/12/2022] Open
Abstract
It is well known that adult humans detect snakes as targets more quickly than flowers as the targets and that how rapidly they detect a snake picture does not differ whether the images are in color or gray-scale, whereas they find a flower picture more rapidly when the images are in color than when the images are gray-scale. In the present study, a total of 111 children were presented with 3-by-3 matrices of images of snakes and flowers in either color or gray-scale displays. Unlike the adults reported on previously, the present participants responded to the target faster when it was in color than when it was gray-scale, whether the target was a snake or a flower, regardless of their age. When detecting snakes, human children appear to selectively attend to their color, which would contribute to the detection being more rapidly at the expense of its precision.
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14
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The number of discernible colors perceived by dichromats in natural scenes and the effects of colored lenses. Vis Neurosci 2008; 25:493-9. [PMID: 18598424 DOI: 10.1017/s0952523808080620] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The number of discernible colors perceived by normal trichromats when viewing natural scenes can be estimated by analyzing idealized color volumes or hyperspectral data obtained from actual scenes. The purpose of the present work was to estimate the relative impairment in chromatic diversity experienced by dichromats when viewing natural scenes and to investigate the effects of colored lenses. The estimates were obtained computationally from the analysis of hyperspectral images of natural scenes and using a quantitative model of dichromats' vision. The color volume corresponding to each scene was represented in CIELAB color space and segmented into cubes of unitary side. For normal trichromats, the number of discernible colors was estimated by counting the number of non-empty cubes. For dichromats, an algorithm simulating for normal observers the appearance of the scenes for dichromats was used, and the number of discernible colors was then counted as for normal trichromats. The effects of colored lenses were estimated by prior filtering the spectral radiance from the scenes with the spectral transmittance function of the lenses. It was found that in dichromatic vision the number of discernible colors was about 7% of normal trichromatic vision. With some colored lenses considerable improvements in chromatic diversity were obtained for trichromats; for dichromats, however, only modest improvements could be obtained with efficiency levels dependent on the combination of scene, lens and type of deficiency.
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15
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Affiliation(s)
- Shozo Yokoyama
- Department of Biology, Emory University, Atlanta, Georgia 30322;
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16
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Prado CC, Pessoa DM, Sousa FLL, Pessoa VF. Behavioural Evidence of Sex-Linked Colour Vision Polymorphism in the Squirrel Monkey Saimiri ustus. Folia Primatol (Basel) 2008; 79:172-84. [DOI: 10.1159/000113537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 10/04/2007] [Indexed: 11/19/2022]
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