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Color Discrimination in Dogs
Abstract
In this study, an experiment was carried out to clarify the color perception in dogs. Two female Shiba breed dogs were trained using an operant conditioning method in which they pressed a switch with their muzzles in order to obtain some food, to discriminate between simultaneously presented colored and gray cards. The left and right positions of the two cards were shifted at random. After the dogs were fully trained, their color perception ability was tested on three primary colors, red, blue and green. The dogs were subjected daily to one or two sessions which consisted of 20 trials each.The criterion of successful discrimination was 3 consecutive sessions with more than 15 correct choices (P<0.05, Chi-square test). In the red vs. gray discrimination test, the dogs respectively took 3 and 12 sessions to reach the criterion. In the blue vs. gray and green vs. gray tests, both dogs were able to attain the criterion by the 13th session. The results of this study suggest that the color vision of dogs is relatively developed and dogs are able to discriminate between all three primary colors and gray.
... As a result, researchers assumed that dogs' color vision is relatively good and dog eyes can distinguish between each of the three major hues as well as gray. However, overall study also implies that dogs have less accurate color perception than species with trichromatic color vision, like human (Tanaka et al., 2000). To sum up other research on related matters, it stated that canines have dichromatic color vision, which is similar to human red-green blindness (Siniscalchi et al., 2017). ...
... • Dogs, practically, can differentiate colors, although not that precisely as humans (Tanaka et al., 2000). • Canines have dichromatic vision, which means they can distinguish the most yellow and blue colors (Siniscalchi et al., 2017), (Jacobs et al., 1993), (Neitz, Geist and Jacobs, 1989). ...
... The concept illustration and the model embodied the interpretation of what owner and dog interior cohabitation means ( Fig.4.11). Color choice inspired by visual cognitions of a dog and human (Tanaka et al., 2000), (Siniscalchi et al., 2017), (Jacobs et al., 1993), (Neitz, Geist and Jacobs, 1989), so as to explore what both of them can perceive relatively the same in terms of color ( Fig.4.10). ...
...Compared to cats, dogs are not able to use vertical areas, therefore space planning with consideration of dogs is less flexible. Owners who live in condensed apartments looking for a functional and balanced living environment, where human and dog cohabit without major compromises on each other's wellbeing. Concept of Environmental Enrichment assist to determine suitable living area for a dog, together with canine sensory features. Therefore, the research investigates on how to manipulate a small interior in order to make cohabitation functional and balanced between both users (Where balcony or patio are absent as an additional living unit).
... ;https://doi.org/10.1101https://doi.org/10. /2024 period of training: to mainly understand the limits of canine color vision (Tanaka et al. 2000, Byosiere 2018, Kasparson et al. 2013. It was hitherto unknown if and how untrained dogs are affected by color cues in their environment. ...
Most of the research on color vision related behaviors in dogs has involved training the dogs to perform visual discrimination tasks. We investigated the meaning of color to untrained Indian free-ranging dogs (FRDs). Using one-time multi-option choice tests for color preference in 134 adult dogs, we found the dogs to prefer yellow objects over blue or gray ones (p < 0.001, Cramer’s V = 0.433) while there was no preference between blue and gray (N = 102, p = 0.165). We next pitted a yellow object against a gray object that had food. Here, the dogs ignored the food to approach the yellow object first, both when the food was biscuit (N = 52, p < 0.001, Cramer’s V = 0.576) and chicken (N = 61, p < 0.001, Cramer’s V = 0.540), indicating the color preference to be quite strong. Color preference has previously been investigated in many other animals and has implications for behaviors like mate choice and foraging. Our study provides a new perspective into the ecology of Indian FRDs and might have implications for pet dogs as well, if they too show this preference.
Highlights
Indian free-ranging dogs (FRDs) show preference toward the color yellow over blue and gray.
Indian FRDs show no preference between blue and gray colors.
Attraction towards a yellow object can be stronger than attraction towards food rewards for Indian FRDs.
... Dogs typically consumed more of the food they chose by smelling first, suggesting they did not need to taste each food to choose (Hall et al., 2017). Odour preference in food has been studied, dogs prefer beef over lamb and horse (Houpt et al., 1978) while recent study show that they prefer beef odour than chicken and fish (Li et al., 2018), Although dogs' ability to distinguish different colours remains controversial (Byosiere et al., 2018), early histological studies suggested that dogs may be able to see only yellow and blue (Jacobs et al., 1993;Neitz et al., 1989), while later studies suggested that dogs are able to appropriately identify a positive stimulus (red, blue, or green compared to grey) (Tanaka et al., 2000). Dogs preferentially use colour over brightness cues when presented with yellow and blue stimuli in a discrimination task (Kasparson et al., 2013). ...
Improper feeding methods can be linked to canine behaviour problems, as the conventional bowl-feeding approach fail to mimic natural behaviour and is associated with obesity. Feeding toys can potentially contribute to the enhancement of dog behaviour by mimicking natural hunting behaviour and promoting increased canine activity. Para rubber is a natural rubber with high flexibility and is tolerant of animal teeth, making it safer for animals compared to plastic and silicone. This study had two main objectives: firstly, to examine dogs' preferences for the scent and colour added to a para rubber toy; and secondly, to explore the impact of using para rubber feeding toys on dog behaviours. The feeding toys were produced from natural rubber, with added scents and colours incorporated during their production. Subsequently, these toys were distributed to dog owners for evaluation. Owners completed the Thai version of the C-BARQ questionnaire, which evaluate canine behaviour both prior to and following a month of interaction with the toys. The findings indicated that dogs exhibited a preference for yellow toys over blue ones, as well as a preference for vanilla-scented toys compared to those with a beef scent. Following one month of consistent use of the para rubber toy, dogs tended to reduce various undesirable behaviours. Notably, excitation behaviour showed a nearly threefold decrease, and this reduction was statistically significant (p = 0.003). These outcomes emphasise the potential of natural rubber feeding toys in mitigating excitation-related behaviours, while also highlighting dogs' preference towards specific colours and scents. Consequently, there is a suggestion that enhancing toys with appealing scents or colours might foster greater interaction between dogs and their toys, potentially leading to a positive influence on their overall behavioural welfare.
... Although discrimination learning encompasses a large number of tasks that we ask of our working dogs, the methods and procedures to produce discrimination learning are typically treated as an accessory question and rarely a central focus of research. Rather, questions on discrimination accuracy/capability for various target odors or cognitive tasks have been the primary focus (82)(83)(84)(85)(86)(87)(88)(89)(90). ...
Dogs are trained for a variety of working roles including assistance, protection, and detection work. Many canine working roles, in their modern iterations, were developed at the turn of the 20th century and training practices have since largely been passed down from trainer to trainer. In parallel, research in psychology has advanced our understanding of animal behavior, and specifically canine learning and cognition, over the last 20 years; however, this field has had little focus or practical impact on working dog training. The aims of this narrative review are to (1) orient the reader to key advances in animal behavior that we view as having important implications for working dog training, (2) highlight where such information is already implemented, and (3) indicate areas for future collaborative research bridging the gap between research and practice. Through a selective review of research on canine learning and behavior and training of working dogs, we hope to combine advances from scientists and practitioners to lead to better, more targeted, and functional research for working dogs.
... 44 Although this is likened to human red/green color blindness (deuteranopia), dogs are capable of discriminating colors by brightness intensities and distinguish red and green from gray. [53][54][55] The visual spectrum in dogs allows for differentiation of hues in the blue spectrum (430-485 nm) and yellow spectrum (500-620 nm) (Fig. 3). 44,[56][57][58] Due to multiple factors, Considerations in Olfaction, Vision, and Audition including a UV-transparent lens and a specific cone sensitivity to sections of the UVspectrum, dogs likely are able to appreciate UV light as a blue-violet color. ...
Canine companions have learned to aid in performing tasks and conducting work for decades. Areas where unique capabilities of working dogs are harnessed are growing. This expansion, alongside efforts to increase domestic purpose-bred stock and awareness of the important role working dogs play in society, is increasing the role veterinarians provide. This article provides a brief overview of 3 key sensory systems in working dogs and highlights considerations for care related to each olfaction, audition, and vision.
... Colors perceived as different hues of blue by humans have a wavelength of about 430-486 nm, while colors perceived as hues of red by humans are between 656-760 nm [53,54]. Therefore, these two hues are distinguishable by dogs and likely perceived as dark yellow/light brown/grey and blue hues [52,55,56]. In order to prevent misunderstanding regarding different color perception between humans and dogs, we will refer to the cups perceived as red by the experimenter as HR (human red) cup, and to the cups perceived as blue by the experimenter as HB (human blue) cups. ...
Simple Summary
Lysosomes are cell organelles that contain enzymes that break down large molecules to be recycled or discarded. When lysosomal enzymes fail to perform this function, molecules become trapped and cause cellular destruction. Mucopolysaccharidosis I (MPS I) is a rare disease that occurs in dogs and humans due to a deficiency of the lysosomal enzyme, alpha-L-iduronidase. Humans affected with MPS I experience mild to severe clinical signs in facial features, skeletal changes, cognitive decline, and heart, liver, and respiratory disease. Similarly, MPS I in dogs also cause facial changes, musculoskeletal degeneration, spinal cord compression, and heart and liver disease. However, the cognitive ability in dogs affected with MPS I has not been investigated. The purpose of this pilot study was to determine the feasibility of conducting cognitive tests on MPS I affected dogs and their cognitive abilities. Three groups of dogs were tested: MPS I untreated, MPS I treated, and clinically normal. Dogs were successfully trained to perform the cognitive tests. Differences in their ability to reach the criterion was evident in attention oddity and scent discrimination tests. This study found cognition testing of dogs affected with MPS I to be feasible and recommend future studies focus on a single cognitive domain at a time.
Abstract
Mucopolysaccharidosis I (MPS I) results from a deficiency of a lysosomal enzyme, alpha-L-iduronidase (IDUA). IDUA deficiency leads to glycosaminoglycan (GAG) accumulation resulting in cellular degeneration and multi-organ dysfunction. The primary aims of this pilot study were to determine the feasibility of cognitive testing MPS I affected dogs and to determine their non-social cognitive abilities with and without gene therapy. Fourteen dogs were tested: 5 MPS I untreated, 5 MPS I treated, and 4 clinically normal. The treated group received intrathecal gene therapy as neonates to replace the IDUA gene. Cognitive tests included delayed non-match to position (DNMP), two-object visual discrimination (VD), reversal learning (RL), attention oddity (AO), and two-scent discrimination (SD). Responses were recorded as correct, incorrect, or no response, and analyzed using mixed effect logistic regression analysis. Significant differences were not observed among the three groups for DNMP, VD, RL, or AO. The MPS I untreated dogs were excluded from AO testing due to failing to pass acquisition of the task, potentially representing a learning or executive function deficit. The MPS I affected group (treated and untreated) was significantly more likely to discriminate between scents than the normal group, which may be due to an age effect. The normal group was comprised of the oldest dogs, and a mixed effect logistic model indicated that older dogs were more likely to respond incorrectly on scent discrimination. Overall, this study found that cognition testing of MPS I affected dogs to be feasible. This work provides a framework to refine future cognition studies of dogs affected with diseases, including MPS I, in order to assess therapies in a more comprehensive manner.
... Rosengren (1969) observed that three out of four trained Cocker Spaniels successfully discriminated red, blue, green, and yellow coloured dishes across various levels of physical luminance and shades of grey (Rosengren, 1969). Moreover, in a two choice discrimination task, where the light intensity on cards was controlled, Tanaka et al. (2000) found that two Shiba dogs were able to appropriately identify a coloured stimulus (red, blue, or green) compared to grey. Kasparson et al. (2013) observed that dogs appear to preferentially use colour cues over luminance cues, under natural photopic lighting conditions, when presented with yellow and blue stimuli in a discrimination task. ...
Due to the composition of the cone photoreceptors in the retina of dogs, it has been proposed they might demonstrate human-like red/green colour blindness. However, some assessments have shown that dogs may still be able to distinguish between red and green. This suggests that dogs may be differentiating between the two colours on the basis of their brightness. To further explore this issue, the present investigation tested dogs’ abilities to differentiate between two colours at different physical luminance levels. Seven dogs were trained on a simultaneous size discrimination task in which two circles were presented on a monitor. The colours of the circles were then varied such that dogs would choose one stimulus if they could discriminate between two colours and a different stimulus if they could not. Four experiments were conducted. The first presented dogs with yellow, blue, green, and red stimuli at their maximum red, green, and blue (RGB) values. All seven dogs were equally proficient at discriminating between red and green, yellow and blue, and black and white stimuli as no difference in performance was observed (p = 0.52). In Experiments 2–4, the four colours were presented with equal physical luminance across three different intensities. All seven dogs successfully discriminated between all four colours when the colours were isoluminant at 34.6 cd/m² as no differences in performance was observed (p = 0.10). When presented with isoluminant stimuli at 41.9 cd/m², a difference was observed between conditions, with the dogs failing to detect red stimuli presented on a green background compared to the achromatic controls (p = 0.03). When presented with stimuli at 49.3 cd/m², a difference was again observed between conditions, but this time the dogs were unable to detect blue stimuli presented on a yellow background compared to the achromatic controls (p < 0.01). These findings demonstrate that luminance levels of stimuli can affect colour discrimination and what dogs are able to see on computer screens. These results have important implications in how cognition is studied in dogs through the use of presenting stimuli on monitors.
... Even with this limitation in mind, dogs appear to be attentive to the colors they can perceive. Two Shiba dogs were able to appropriately identify a positive stimulus (red, blue, or green compared to grey) in a two-choice discrimination task, where the light intensity on the cards was 450-500 lux (Tanaka, Watanabe, Eguchi, & Yoshimoto, 2000). The authors of this study suggested that color vision is relatively well developed, considering the dogs were able to discriminate between all three primary colors and grey. ...
Over the last 20 years, a large amount of research has been conducted in an attempt to uncover the cognitive abilities of the domestic dog. While substantial advancements have been made, progress has been impeded by the fact that little is known about how dogs visually perceive their external environment. It is imperative that future research determines more precisely canine visual processing capabilities, particularly considering the increasing number of studies assessing cognition via paradigms requiring vision. This review discusses current research on visual cognition and emphasizes the importance of understanding dog visual processing. We review several areas of vision research in domestic dogs, such as sensitivity to light, visual perspective, visual acuity, form perception, and color vision, with a focus on how these abilities may affect performance in cognition tasks. Additionally, we consider the immense diversity seen in dog morphology and explore ways in which these physical differences, particularly in facial morphology, may result in, or perhaps even be caused by, different visual processing capacities in dogs. Finally, we suggest future directions for research in dog vision and cognition.
... Less well established is the dog's visual acuity and their ability to distinguish different colours (Miller and Murphy 1995). While many early studies of colour vision suggested dogs lacked colour vision (Neitz et al. 1989;Rosengren 1969), there is now both behavioural and anatomic evidence that dogs have a potential to perceive colour (Jacobs 1983;Tanaka et al. 2000). However, colour vision capacities in dogs remain unclear. ...
Susceptibility to geometrical visual illusions has been tested in a number of non-human animal species, providing important information about how these species perceive their environment. Considering their active role in human lives, visual illusion susceptibility was tested in domestic dogs (Canis familiaris). Using a two-choice simultaneous discrimination paradigm, eight dogs were trained to indicate which of two presented circles appeared largest. These circles were then embedded in three different illusory displays; a classical display of the Ebbinghaus–Titchener illusion; an illusory contour version of the Ebbinghaus–Titchener illusion; and the classical display of the Delboeuf illusion. Significant results were observed in both the classical and illusory contour versions of the Ebbinghaus–Titchener illusion, but not the Delboeuf illusion. However, this susceptibility was reversed from what is typically seen in humans and most mammals. Dogs consistently indicated that the target circle typically appearing larger in humans appeared smaller to them, and that the target circle typically appearing smaller in humans, appeared larger to them. We speculate that these results are best explained by assimilation theory rather than other visual cognitive theories explaining susceptibility to this illusion in humans. In this context, we argue that our findings appear to reflect higher-order conceptual processing in dogs that cannot be explained by accounts restricted to low-level mechanisms of early visual processing.
... In order to make brightness of coloured stimuli an unreliable cue, the stimuli are either equalized in their brightness or the brightness is varied during the training [3,8]. The first method relies on assumptions (often groundless or completely incorrect) about the animal's luminous efficiency function (i.e. the spectral sensitivity function, which determines the brightness of the stimuli as seen by the animal) [9][10][11]. The second method is not only labour-and time-consuming; its main shortcoming is that animals are actually trained that brightness is an unreliable cue, even though they could use it when discriminating the stimuli. ...
The results of early studies on colour vision in dogs led to the conclusion that chromatic cues are unimportant for dogs during their normal activities. Nevertheless, the canine retina possesses two cone types which provide at least the potential for colour vision. Recently, experiments controlling for the brightness information in visual stimuli demonstrated that dogs have the ability to perform chromatic discrimination. Here, we show that for eight previously untrained dogs colour proved to be more informative than brightness when choosing between visual stimuli differing both in brightness and chromaticity. Although brightness could have been used by the dogs in our experiments (unlike previous studies), it was not. Our results demonstrate that under natural photopic lighting conditions colour information may be predominant even for animals that possess only two spectral types of cone photoreceptors.
Most of the research on color vision related behaviors in dogs has involved training the dogs to perform visual discrimination tasks. We investigated the importance of color to untrained Indian free-ranging dogs (FRDs). Using one-time multi-option choice tests for color preference in 134 adult dogs, we found the dogs to prefer yellow objects over blue or gray ones while there was no preference between blue and gray. We next pitted a yellow object against a gray object that had food. Here, the dogs ignored the food (biscuit or chicken) to approach the yellow object first indicating the color preference to be quite strong. Color preference has previously been investigated in many other animals and has implications for behaviors like mate choice and foraging. Our study provides a new perspective into the ecology of Indian FRDs and might have implications for companion dogs as well, if they too show this preference.
Supplementary Information
The online version contains supplementary material available at 10.1007/s10071-024-01928-9.
During two retreats in 2017 and 2020, a group of international scientists convened to explore the Human-Animal Bond. The meetings, hosted by the Wallis Annenberg PetSpace Leadership Institute, took a broad view of the human-dog relationship and how interactions between the two may benefit us medically, psychologically or through their service as working dogs (e.g. guide dogs, explosive detection, search and rescue, cancer detection). This Frontiers’ Special Topic has collated the presentations into a broad collection of 14 theoretical and review papers summarizing the latest research and practice in the historical development of our deepening bond with dogs, the physiological and psychological changes that occur during human-dog interactions (to both humans and dogs) as well as the selection, training and welfare of companion animals and working dogs. The overarching goals of this collection are to contribute to the current standard of understanding of human-animal interaction, suggest future directions in applied research, and to consider the interdisciplinary societal implications of the findings.
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