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Author Farmer, K.; Krueger, K.; Byrne, R. pdf  url
doi  openurl
  Title Visual laterality in the domestic horse (Equus caballus) interacting with humans Type Journal Article
  Year 2010 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 13 Issue (up) Pages 229-238  
  Keywords Horse – Laterality – Eye preference – Emotion – Vision  
  Abstract Most horses have a side on which they are easier to handle and a direction they favour when working on a circle, and recent studies have suggested a correlation between emotion and visual laterality when horses observe inanimate objects. As such lateralisation could provide important clues regarding the horse’s cognitive processes, we investigated whether horses also show laterality in association with people. We gave horses the choice of entering a chute to left or right, with and without the passive, non-interactive presence of a person unknown to them. The left eye was preferred for scanning under both conditions, but significantly more so when a person was present. Traditionally, riders handle horses only from the left, so we repeated the experiment with horses specifically trained on both sides. Again, there was a consistent preference for left eye scanning in the presence of a person, whether known to the horses or not. We also examined horses interacting with a person, using both traditionally and bilaterally trained horses. Both groups showed left eye preference for viewing the person, regardless of training and test procedure. For those horses tested under both passive and interactive conditions, the left eye was preferred significantly more during interaction. We suggest that most horses prefer to use their left eye for assessment and evaluation, and that there is an emotional aspect to the choice which may be positive or negative, depending on the circumstances. We believe these results have important practical implications and that emotional laterality should be taken into account in training methods.  
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  Call Number Equine Behaviour @ team @ Serial 4953  
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Author Smith, S.; Goldman, L. url  openurl
  Title Color discrimination in horses Type Journal Article
  Year 1999 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 62 Issue (up) 1 Pages 13-25  
  Keywords Horses; Vision; Color; Discrimination; Behavior  
  Abstract Four Arabian horses and one Thoroughbred were presented with a series of two-choice color vs. gray discrimination problems. Testing was done in a stall containing a wall with two translucent panels that were illuminated from behind by light projected through color or gray filters to provide the discriminative stimuli. Horses first learned to push one of the panels in order to receive the food reward behind the positive stimulus in an achromatic light-dark discrimination task, and were then tested on their ability to discriminate between gray and four individual colors: red (617 nm), yellow (581 nm), green (538 nm), and blue (470 nm). The criterion for learning was set at 85% correct responses, and final testing for all color vs. gray discriminations involved grays of varying intensities, making brightness an irrelevant cue. Three subjects were tested with all four colors. Two of those subjects successfully reached the criterion for learning on all four color vs. gray discriminations, while the third reached criterion with red and blue, but performed at chance levels for yellow and green. A fourth horse was only tested with green and yellow, and a fifth only with blue, and both of those horses successfully reached criterion on the discriminations they attempted. With the exception of the one subject's poor performance with yellow and green, there was no significant difference between horses on any of the discrimination tasks, and no significant difference in their performance with different colors. The results suggest that horses have color vision that is at least dichromatic, although partial color-blindness may occur in some individuals.  
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  Call Number refbase @ user @ Serial 850  
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Author Hirata, S. doi  openurl
  Title A note on the responses of chimpanzees (Pan troglodytes) to live self-images on television monitors Type Journal Article
  Year 2007 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 75 Issue (up) 1 Pages 85-90  
  Keywords Animals; *Discrimination Learning; Female; Male; Pan troglodytes/*psychology; *Self Concept; Self Psychology; Social Behavior; Television  
  Abstract The majority of studies on self-recognition in animals have been conducted using a mirror as the test device; little is known, however, about the responses of non-human primates toward their own images in media other than mirrors. This study provides preliminary data on the reactions of 10 chimpanzees to live self-images projected on two television monitors, each connected to a different video camera. Chimpanzees could see live images of their own faces, which were approximately life-sized, on one monitor. On the other monitor, they could see live images of their whole body, which were approximately one-fifth life-size, viewed diagonally from behind. In addition, several objects were introduced into the test situation. Out of 10 chimpanzees tested, 2 individuals performed self-exploratory behaviors while watching their own images on the monitors. One of these two chimpanzees successively picked up two of the provided objects in front of a monitor, and watched the images of these objects on the monitor. The results indicate that these chimpanzees were able to immediately recognize live images of themselves or objects on the monitors, even though several features of these images differed from those of their previous experience with mirrors.  
  Address Great Ape Research Institute, Hayashibara Biochemical Laboratories Inc., Okayama, Japan. hirata@gari.be.to  
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  ISSN 0376-6357 ISBN Medium  
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  Notes PMID:17324534 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4145  
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Author Hanggi, E.B.; Ingersoll, J.F. doi  openurl
  Title Stimulus discrimination by horses under scotopic conditions Type Journal Article
  Year 2009 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 82 Issue (up) 1 Pages 45-50  
  Keywords Discrimination learning; Equine; Horse; Night vision; Scotopic vision  
  Abstract Scotopic vision in horses (Equus caballus) was investigated using behavioral measurements for the first time. Four horses were tested for the ability to make simple visual discriminations of geometric figures (circles and triangles) under various brightness levels within an enclosed building. Measurements of brightness ranging from 10.37 to 24.12 magnitudes per square arcsecond (mag/arcsec2; in candelas per square meter--7.70 to 2.43E-05 cd/m2) were taken using a Sky Quality Meter. These values approximated outdoor conditions ranging from twilight in open country to a dark moonless night in dense forest. The horses were able to solve the discrimination problems in all brightness settings up to 23.77 mag/arcsec2 (3.35E-05 cd/m2). Moreover, they easily navigated their way around obstacles located within the testing area in extremely dim light (>23.50 mag/arcsec2; 4.30E-05 cd/m2), which were in conditions too dark for the human experimenters to see. These findings support physiological data that reveal a rod-dominated visual system as well as observations of equine activity at night.  
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  Call Number Equine Behaviour @ team @ Serial 5051  
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Author Hanggi, E.B.; Ingersoll, J.F. url  doi
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  Title Lateral vision in horses: A behavioral investigation Type Journal Article
  Year 2012 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 91 Issue (up) 1 Pages 70-76  
  Keywords Lateral vision; Horse; Equine; Stimulus discrimination; Field of view; Peripheral  
  Abstract This study investigated lateral vision in horses (Equus caballus) for the first time from a behavioral point of view. Three horses were tested using a novel experimental design to determine the range of their lateral and caudolateral vision with respect to stimulus detection and discrimination. Real-life stimuli were presented along a curvilinear wall in one of four different positions (A, B, C, D) and one of two height locations (Top, Bottom) on both sides of the horse. To test for stimulus detection, the correct stimulus was paired against a control; for stimulus discrimination, the correct stimulus was paired against another object. To indicate that the correct stimulus was detected or discriminated, the horses pushed one of two paddles. All horses scored significantly above chance on stimulus detection trials regardless of stimulus position or location. They also accurately discriminated between stimuli when objects appeared in positions A, B, and C for the top or bottom locations; however, they failed to discriminate these stimuli at position D. This study supports physiological descriptions of the equine eye and provides new behavioral data showing that horses can detect the appearance of objects within an almost fully encompassing circle and are able to identify objects within most but not all of their panoramic field of view.  
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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5621  
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Author Mills, D.S.; Riezebos, M. doi  openurl
  Title The role of the image of a conspecific in the regulation of stereotypic head movements in the horse Type Journal Article
  Year 2005 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 91 Issue (up) 1-2 Pages 155-165  
  Keywords Behaviour; Horse; Nodding; Perception; Stereotypy; Vision; Weaving  
  Abstract Weaving is a common locomotor stereotypy in horses, which has been shown to be reduced by the presence of a mirror in the stable; however, it remains unclear whether this effect is due to the reflected image of a horse or some other property associated with the introduction of a mirror. To investigate this further, the response of six known weaving horses to each of three different types of poster was recorded. The poster images consisted of a life-size image of a horse's face (true image), a version of the same image cut into 54 squares, which were then randomly rearranged (pixilated image) and a blank (white image) display of the same size as the other posters. Four observation periods were included in each of the two days of observation per treatment condition: 08:00-08:30 h, 10:00-10:30 h, 12:00-12:30 h and 16:00-17:00 h. The first observation period was followed by the provision of concentrate feed and forage, the second observation period by exercise, the third by further forage and the fourth by concentrate feed and forage. The horses' activities and positions in the box were scanned at 1 min intervals and the number of observations registering each activity and position was calculated as a percentage of the total number of observations for each observation period. Weaving was significantly less when the horses were provided with the image of a horse's face (mean percentage of observations +/- S.E.M.; 5.56 +/- 1.57), compared to both the pixilated (14.85 +/- 3.06) and white (20.52 +/- 4.12) images. Nodding was significantly less when provided with the true image of a horse (0.45 +/- 0.15) compared to the pixilated image (2.15 +/- 0.67). The pattern of weaving throughout the day differed from that of nodding, and together these results suggest that the two behaviours are not analogous. The presence of the image of the horse's face was associated with a significant increase in alertness (F112,2 = 11.31, p < 0.001) and recorded time spent looking at the poster(F112,2 = 3.46, p < 0.05). The timing of stereotypic head movements in the horse in this study suggests that they are not associated with boredom, or lack of stimulation but rather acute frustration.  
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  Call Number refbase @ user @ Serial 307  
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Author Timney, B.; Keil, K. doi  openurl
  Title Local and global stereopsis in the horse Type Journal Article
  Year 1999 Publication Vision Research Abbreviated Journal Vision Res  
  Volume 39 Issue (up) 10 Pages 1861-1867  
  Keywords Animals; Depth Perception/*physiology; Female; Horses/*physiology; Pattern Recognition, Visual/physiology; Psychophysics; Sensory Thresholds/physiology; Vision, Binocular/physiology; Vision, Monocular/physiology  
  Abstract 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.  
  Address Department of Psychology, Faculty of Social Science, University of Western Ontario, London, Canada. timney@julian.uwo.ca  
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  ISSN 0042-6989 ISBN Medium  
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  Notes PMID:10343877 Approved yes  
  Call Number Equine Behaviour @ team @ Serial 3580  
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Author Cheung, C.; Akiyama, T.E.; Ward, J.M.; Nicol, C.J.; Feigenbaum, L.; Vinson, C.; Gonzalez, F.J. doi  openurl
  Title Diminished hepatocellular proliferation in mice humanized for the nuclear receptor peroxisome proliferator-activated receptor alpha Type Journal Article
  Year 2004 Publication Cancer research Abbreviated Journal Cancer Res  
  Volume 64 Issue (up) 11 Pages 3849-3854  
  Keywords Animals; Anticholesteremic Agents/pharmacology; Carcinogens/pharmacology; Cell Division; DNA Replication/drug effects; Fatty Acids/metabolism; Hepatocytes/cytology/drug effects/metabolism/*physiology; Humans; Mice; Mice, Transgenic; Oxidation-Reduction; Peroxisome Proliferators/pharmacology; Pyrimidines/pharmacology; Receptors, Cytoplasmic and Nuclear/genetics/*physiology; Species Specificity; Transcription Factors/genetics/*physiology  
  Abstract Lipid-lowering fibrate drugs function as agonists for the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha). Sustained activation of PPARalpha leads to the development of liver tumors in rats and mice. However, humans appear to be resistant to the induction of peroxisome proliferation and the development of liver cancer by fibrate drugs. The molecular basis of this species difference is not known. To examine the mechanism determining species differences in peroxisome proliferator response between mice and humans, a PPARalpha-humanized mouse line was generated in which the human PPARalpha was expressed in liver under control of the tetracycline responsive regulatory system. The PPARalpha-humanized and wild-type mice responded to treatment with the potent PPARalpha ligand Wy-14643 as revealed by induction of genes encoding peroxisomal and mitochondrial fatty acid metabolizing enzymes and resultant decrease of serum triglycerides. However, surprisingly, only the wild-type mice and not the PPARalpha-humanized mice exhibited hepatocellular proliferation as revealed by elevation of cell cycle control genes, increased incorporation of 5-bromo-2'-deoxyuridine into hepatocyte nuclei, and hepatomegaly. These studies establish that following ligand activation, the PPARalpha-mediated pathways controlling lipid metabolism are independent from those controlling the cell proliferation pathways. These findings also suggest that structural differences between human and mouse PPARalpha are responsible for the differential susceptibility to the development of hepatocarcinomas observed after treatment with fibrates. The PPARalpha-humanized mice should serve as models for use in drug development and human risk assessment and to determine the mechanism of hepatocarcinogenesis of peroxisome proliferators.  
  Address Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA  
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  ISSN 0008-5472 ISBN Medium  
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  Notes PMID:15172993 Approved no  
  Call Number refbase @ user @ Serial 74  
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Author Garamszegi, L.Z.; Møller, A.P.; Erritzøe, J. doi  openurl
  Title Coevolving avian eye size and brain size in relation to prey capture and nocturnality Type Journal Article
  Year 2002 Publication Proceedings of the Royal Society of London. Series B: Biological Sciences Abbreviated Journal Proc Roy Soc Lond B Biol Sci  
  Volume 269 Issue (up) 1494 Pages 961-967  
  Keywords adaptation; behaviour; brain size; coevolution; eye size; vision  
  Abstract 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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  Notes 10.1098/rspb.2002.1967 Approved no  
  Call Number Equine Behaviour @ team @ Serial 5452  
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Author Wolfe, J.M. openurl 
  Title Hidden visual processes Type Journal Article
  Year 1983 Publication Scientific American Abbreviated Journal Sci Am  
  Volume 248 Issue (up) 2 Pages 94-103  
  Keywords Color Perception/*physiology; Humans; Motion Perception/physiology; Ocular Physiology; Vision; Visual Perception/*physiology  
  Abstract Isoluminant stimulus is an image whose edges are defined only by a change in color, not by change in brightness. The stimulus here is imperfect: the blue parts and the green parts of the image are only as nearly equal in brightness as they can be on the printed page. Moreover, the change in brightness beyond the edge of the page is apparent, and so is the fact that the reader is holding the magazine at reading distance. When such cues are removed under laboratory conditions, subjects faced with an isoluminant stimulus prove unable to bring its edges into focus. This deficiency contributes to making a familiar face hard to recognize. The experiment indicates that the brain process underlying visual accommodation (the focusing of the eyes) cannot “see” color; it is a hidden process distinct from the processes that lead to perception. The image shows Groucho Marx as he appeared in the motion picture Horse Feathers.  
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  ISSN 0036-8733 ISBN Medium  
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  Notes PMID:6836258 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4066  
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