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Author |
Macuda, T.; Timney, B. |
![find record details (via OpenURL) openurl](img/xref.gif)
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Title |
Luminance and chromatic discrimination in the horse (Equus caballus) |
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Journal Article |
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Year |
1999 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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44 |
Issue |
3 |
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301-307 |
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Colour vision; Chromatic discrimination; Luminance discrimination; Horse |
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Abstract |
Equine colour vision was measured under conditions that minimised the possibility of animals using brightness cues to make chromatic discriminations. In a two-stage study, we first obtained luminance discrimination functions for achromatic targets then tested for chromatic discrimination over a range of target luminances. Horses were trained on a two-choice discrimination task. The positive stimulus was varied in luminance and/or colour using neutral density and broad band colour filters. The negative stimulus appeared as a uniform grey. In the brightness discrimination task, the horses performed well at large luminance differences but their percentage of correct responses declined to near chance levels at differences of less than 0.2 log units. In addition, a decrement in performance was noted at luminance differences of less than 0.2 log units for green and yellow chromatic discrimination functions, suggesting that horses cannot easily discriminate yellow and green from grey. However, the chromatic discrimination functions for red and blue showed that animals performed very well across the full range of target luminances. These results suggest that horses are at least dichromats. |
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844 |
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Author |
Harman, A.M.; Moore, S.; Hoskins, R.; Keller, P. |
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Title |
Horse vision and an explanation for the visual behaviour originally explained by the 'ramp retina' |
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Journal Article |
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Year |
1999 |
Publication |
Equine veterinary journal |
Abbreviated Journal |
Equine Vet J |
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Volume |
31 |
Issue |
5 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
384-390 |
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Animals; Behavior, Animal; Cell Count; Eye/*anatomy & histology; Ganglia, Sensory/cytology; Horses/*physiology; Refractive Errors/veterinary; Retina/cytology/*physiology; Vision/*physiology; Visual Acuity; Visual Fields |
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Here we provide confirmation that the 'ramp retina' of the horse, once thought to result in head rotating visual behaviour, does not exist. We found a 9% variation in axial length of the eye between the streak region and the dorsal periphery. However, the difference was in the opposite direction to that proposed for the 'ramp retina'. Furthermore, acuity in the narrow, intense visual streak in the inferior retina is 16.5 cycles per degree compared with 2.7 cycles per degree in the periphery. Therefore, it is improbable that the horse rotates its head to focus onto the peripheral retina. Rather, the horse rotates the nose up high to observe distant objects because binocular overlap is oriented down the nose, with a blind area directly in front of the forehead. |
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Department of Psychology, University of Western Australia, Nedlands, Australia |
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0425-1644 |
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PMID:10505953 |
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refbase @ user @ |
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836 |
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Blackmore, T.L.; Foster, T.M.; Sumpter, C.E.; Temple, W. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
An investigation of colour discrimination with horses (Equus caballus) |
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Journal Article |
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2008 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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78 |
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3 |
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387-396 |
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Chromatic discrimination; Colour vision; Horse; Operant |
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The ability of four horses (Equus caballus) to discriminate coloured (three shades of blue, green, red, and yellow) from grey (neutral density) stimuli, produced by back projected lighting filters, was investigated in a two response forced-choice procedure. Pushes of the lever in front of a coloured screen were occasionally reinforced, pushes of the lever in front of a grey screen were never reinforced. Each colour shade was randomly paired with a grey that was brighter, one that was dimmer, and one that approximately matched the colour in terms of brightness. Each horse experienced the colours in a different order, a new colour was started after 85% correct responses over five consecutive sessions or if accuracy showed no trend over sessions. All horses reached the 85% correct with blue versus grey, three horses did so with both yellow and green versus grey. All were above chance with red versus grey but none reached criterion. Further analysis showed the wavelengths of the green stimuli used overlapped with the yellow. The results are consistent with histological and behavioural studies that suggest that horses are dichromatic. They differ from some earlier data in that they indicate horses can discriminate yellow and blue, but that they may have deficiencies in discriminating red and green. |
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0376-6357 |
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Equine Behaviour @ team @ |
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5336 |
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Siniscalchi, M.; Sasso, R.; Pepe, A.M.; Vallortigara, G.; Quaranta, A. |
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Title |
Dogs turn left to emotional stimuli |
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Journal Article |
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Year |
2010 |
Publication |
Behavioural Brain Research |
Abbreviated Journal |
Behav. Brain. Res. |
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208 |
Issue |
2 |
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516-521 |
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Dog; Laterality; Vision; Behaviour; Physiology; Cognition; Emotion; Animal welfare |
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During feeding behaviour, dogs were suddenly presented with 2D stimuli depicting the silhouette of a dog, a cat or a snake simultaneously into the left and right visual hemifields. A bias to turn the head towards the left rather than the right side was observed with the cat and snake stimulus but not with the dog stimulus. Latencies to react following stimulus presentation were lower for left than for right head turning, whereas times needed to resume feeding behaviour were higher after left rather than after right head turning. When stimuli were presented only to the left or right visual hemifields, dogs proved to be more responsive to left side presentation, irrespective of the type of stimulus. However, cat and snake stimuli produced shorter latencies to react and longer times to resume feeding following left rather than right monocular visual hemifield presentation. Results demonstrate striking lateralization in dogs, with the right side of the brain more responsive to threatening and alarming stimuli. Possible implications for animal welfare are discussed. |
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0166-4328 |
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Equine Behaviour @ team @ |
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5080 |
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Author |
Anderson, C.; Franks, N.R. |
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Title |
Teams in animal societies |
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Journal Article |
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Year |
2001 |
Publication |
Behavioral Ecology |
Abbreviated Journal |
Behav. Ecol. |
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12 |
Issue |
5 |
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534-540 |
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animal societies, cooperation, division of labor, groups, invertebrates, task types, teams, vertebrates |
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We review the existence of teams in animal societies. Teams have previously been dismissed in all but a tiny minority of insect societies. “Team” is a term not generally used in studies of vertebrates. We propose a new rigorous definition of a team that may be applied to both vertebrate and invertebrate societies. We reconsider what it means to work as a team or group and suggest that there are many more teams in insect societies than previously thought. A team task requires different subtasks to be performed concurrently for successful completion. There is a division of labor within a team. Contrary to previous reviews of teams in social insects, we do not constrain teams to consist of members of different castes and argue that team members may be interchangeable. Consequently, we suggest that a team is simply the set of individuals that performs a team task. We contrast teams with groups and suggest that a group task requires the simultaneous performance and cooperation of two or more individuals for successful completion. In a group, there is no division of labor--each individual performs the same task. We also contrast vertebrate and invertebrate teams and find that vertebrate teams tend to be associated with hunting and are based on individual recognition. Invertebrate teams occur in societies characterized by a great deal of redundancy, and we predict that teams in insect societies are more likely to be found in large polymorphic (“complex”) societies than in small monomorphic (“simple”) societies. |
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10.1093/beheco/12.5.534 |
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2070 |
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Bartoš, L.; Bartošová, J.; Starostová, L. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Position of the head is not associated with changes in horse vision |
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Journal Article |
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Year |
2008 |
Publication |
Equine Veterinary Journal |
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40 |
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6 |
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599-601 |
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horse; horse vision; head position; pupil rotation |
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It has become accepted that the horse cannot see directly in front when the nose is lowered and must therefore rely on the rider. We tested the hypothesis that this conclusion would be correct only if the horse did not adjust the eyeball horizontal axis to changes of the head position. The results of the present study suggest that it is unlikely that horses have limited vision in relation to their head position when driven by the rider, and that the horse maintains the optimal horizontal eyeball position regardless of head position relative to the ground. |
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Blackwell Publishing Ltd |
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2042-3306 |
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Equine Behaviour @ team @ |
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5679 |
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Garamszegi, L.Z.; Møller, A.P.; Erritzøe, J. |
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Title |
Coevolving avian eye size and brain size in relation to prey capture and nocturnality |
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Journal Article |
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2002 |
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Proceedings of the Royal Society of London. Series B: Biological Sciences |
Abbreviated Journal |
Proc Roy Soc Lond B Biol Sci |
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269 |
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1494 |
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961-967 |
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adaptation; behaviour; brain size; coevolution; eye size; vision |
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Behavioural adaptation to ecological conditions can lead to brain size evolution. Structures involved in behavioural visual information processing are expected to coevolve with enlargement of the brain. Because birds are mainly vision–oriented animals, we tested the predictions that adaptation to different foraging constraints can result in eye size evolution, and that species with large eyes have evolved large brains to cope with the increased amount of visual input. Using a comparative approach, we investigated the relationship between eye size and brain size, and the effect of prey capture technique and nocturnality on these traits. After controlling for allometric effects, there was a significant, positive correlation between relative brain size and relative eye size. Variation in relative eye and brain size were significantly and positively related to prey capture technique and nocturnality when a potentially confounding variable, aquatic feeding, was controlled statistically in multiple regression of independent linear contrasts. Applying a less robust, brunching approach, these patterns also emerged, with the exception that relative brain size did not vary with prey capture technique. Our findings suggest that relative eye size and brain size have coevolved in birds in response to nocturnal activity and, at least partly, to capture of mobile prey. |
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10.1098/rspb.2002.1967 |
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Equine Behaviour @ team @ |
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5452 |
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Hare, B.; Brown, M.; Williamson, C.; Tomasello, M. |
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Title |
The domestication of social cognition in dogs |
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Journal Article |
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Year |
2002 |
Publication |
Science (New York, N.Y.) |
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Science |
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298 |
Issue |
5598 |
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1634-1636 |
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Animals; *Animals, Domestic; *Behavior, Animal; *Cognition; *Cues; *Dogs; Food; Humans; Memory; Pan troglodytes; *Social Behavior; Species Specificity; Vision; Wolves |
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Dogs are more skillful than great apes at a number of tasks in which they must read human communicative signals indicating the location of hidden food. In this study, we found that wolves who were raised by humans do not show these same skills, whereas domestic dog puppies only a few weeks old, even those that have had little human contact, do show these skills. These findings suggest that during the process of domestication, dogs have been selected for a set of social-cognitive abilities that enable them to communicate with humans in unique ways. |
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Department of Anthropology, Harvard University, Cambridge, MA 02138, USA. bhare@fas.harvard.edu |
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1095-9203 |
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PMID:12446914 |
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refbase @ user @ |
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595 |
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Hall, C.A.; Cassaday, H.J.; Derrington, A.M. |
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The effect of stimulus height on visual discrimination in horses |
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Journal Article |
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Year |
2003 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
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81 |
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7 |
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1715-1720 |
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Animals; *Discrimination Learning/physiology; Female; Horses/physiology/*psychology; Male; Orientation; *Photic Stimulation; Vision/*physiology |
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This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training. |
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School of Land-based Studies, Nottingham Trent University, Brackenhurst College Campus, Southwell, Nottinghamshire, England NG25 0QF. carol.hall@ntu.ac.uk |
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0021-8812 |
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PMID:12854807 |
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refbase @ user @ |
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835 |
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Author |
Timney, B.; Keil, K. |
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Title |
Local and global stereopsis in the horse |
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Journal Article |
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Year |
1999 |
Publication |
Vision Research |
Abbreviated Journal |
Vision Res |
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39 |
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10 |
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1861-1867 |
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Animals; Depth Perception/*physiology; Female; Horses/*physiology; Pattern Recognition, Visual/physiology; Psychophysics; Sensory Thresholds/physiology; Vision, Binocular/physiology; Vision, Monocular/physiology |
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Although horses have laterally-placed eyes, there is substantial binocular overlap, allowing for the possibility that these animals have stereopsis. In the first experiment of the present study we measured local stereopsis by obtaining monocular and binocular depth thresholds for renal depth stimuli. On all measures, the horses' binocular performance was superior to their monocular. When depth thresholds were obtained, binocular thresholds were several times superior to those obtained monocularly, suggesting that the animals could use stereoscopic information when it was available. The binocular thresholds averaged about 15 min arc. In the second experiment we obtained evidence for the presence of global stereopsis by testing the animals' ability to discriminate between random-dot stereograms with and without consistent disparity information. When presented with such stimuli they showed a strong preference for the cyclopean equivalent of the positive stimulus with the real depth. These results provide the first behavioral demonstration of a full range of stereoscopic skills in a lateral-eyed mammal. |
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Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Canada. timney@julian.uwo.ca |
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0042-6989 |
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PMID:10343877 |
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yes |
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Equine Behaviour @ team @ |
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3580 |
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