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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 1 Pages (up) 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 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 1 Pages (up) 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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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5051  
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Author Hanggi, E.B.; Ingersoll, J.F. url  doi
openurl 
  Title Lateral vision in horses: A behavioral investigation Type Journal Article
  Year 2012 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 91 Issue 1 Pages (up) 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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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5621  
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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 1 Pages (up) 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 Wolfe, J.M. openurl 
  Title Hidden visual processes Type Journal Article
  Year 1983 Publication Scientific American Abbreviated Journal Sci Am  
  Volume 248 Issue 2 Pages (up) 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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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 1-2 Pages (up) 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 Regolin, L.; Marconato, F.; Vallortigara, G. doi  openurl
  Title Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus) Type Journal Article
  Year 2004 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 7 Issue 3 Pages (up) 162-170  
  Keywords Animals; Discrimination Learning/physiology; Dominance, Cerebral/*physiology; Female; Form Perception/*physiology; Imprinting (Psychology)/*physiology; Pattern Recognition, Visual/*physiology; Photic Stimulation; Random Allocation; Vision, Monocular/*physiology  
  Abstract Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders (“amodal completion”). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a “global” analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a “featural” analysis of visual scenes.  
  Address Department of General Psychology, University of Padova, Via Venezia 8, 35131, Padova, Italy. lucia.regolin@unipd.it  
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  ISSN 1435-9448 ISBN Medium  
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  Notes PMID:15241654 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2519  
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Author Kilian, A.; Fersen, L. von; Güntürkün, O. url  doi
openurl 
  Title Left hemispheric advantage for numerical abilities in the bottlenose dolphin Type Journal Article
  Year 2005 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 68 Issue 2 Pages (up) 179-184  
  Keywords Bottlenose dolphin; Hemispheric specialization; Monocular vision; Numerical ability  
  Abstract In a two-choice discrimination paradigm, a bottlenose dolphin discriminated relational dimensions between visual numerosity stimuli under monocular viewing conditions. After prior binocular acquisition of the task, two monocular test series with different number stimuli were conducted. In accordance with recent studies on visual lateralization in the bottlenose dolphin, our results revealed an overall advantage of the right visual field. Due to the complete decussation of the optic nerve fibers, this suggests a specialization of the left hemisphere for analysing relational features between stimuli as required in tests for numerical abilities. These processes are typically right hemisphere-based in other mammals (including humans) and birds. The present data provide further evidence for a general right visual field advantage in bottlenose dolphins for visual information processing. It is thus assumed that dolphins possess a unique functional architecture of their cerebral asymmetries.  
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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5366  
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Author Marten, K.; Psarakos, S. doi  openurl
  Title Using self-view television to distinguish between self-examination and social behavior in the bottlenose dolphin (Tursiops truncatus) Type Journal Article
  Year 1995 Publication Consciousness and Cognition Abbreviated Journal Conscious Cogn  
  Volume 4 Issue 2 Pages (up) 205-224  
  Keywords Animal Communication; Animals; *Attention; Discrimination Learning; Dolphins/*psychology; Female; Male; *Self Concept; *Social Behavior; *Television; *Visual Perception  
  Abstract In mirror mark tests dolphins twist, posture, and engage in open-mouth and head movements, often repetitive. Because postures and an open mouth are also dolphin social behaviors, we used self-view television as a manipulatable mirror to distinguish between self-examination and social behavior. Two dolphins were exposed to alternating real-time self-view (“mirror mode”) and playback of the same to determine if they distinguished between them. The adult male engaged in elaborate open-mouth behaviors in mirror mode, but usually just watched when played back the same material. Mirror mode behavior was also compared to interacting with real dolphins (controls). Mark tests were conducted, as well as switches from front to side self-views to see if the dolphins turned. They presented marked areas to the self-view television and turned. The results suggest self-examination over social behavior.  
  Address Earthtrust, Kailua, Hawaii 96734, USA  
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  ISSN 1053-8100 ISBN Medium  
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  Notes PMID:8521259 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4164  
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Author Saslow, C.A. url  doi
openurl 
  Title Understanding the perceptual world of horses Type Journal Article
  Year 2002 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 78 Issue 2-4 Pages (up) 209-224  
  Keywords Horse; Perception; Vision; Olfaction; Touch; Hearing; Pain; Training; Psychophysics; Umwelt  
  Abstract From the viewpoint of experimental psychology, there are two problems with our current knowledge of equine perception. The first is that the behavioral and neurophysiological research in this area has enormous gaps, reflecting that this animal is not a convenient laboratory subject. The second is that the horse, having been a close companion to humans for many millennia, entrenched anecdotal wisdom is often hard to separate from scientific fact. Therefore, any summary at present of equine perception has to be provisional. The horse appears to have developed a visual system particularly sensitive to dim light and movement, it may or may not have a weak form of color vision in part of the retina, it has little binocular overlap, and its best acuity is limited to a restricted horizontal band which is aimed primarily by head/neck movements. However, the total field of view is very large. Overall, as would be expected for a prey animal, horse vision appears to have evolved more for detection of predator approach from any angle than for accurate visual identification of stationary objects, especially those seen at a distance. It is likely that, as for most mammals except the primates, horses rely more heavily on their other senses for forming a view of their world. Equine high-frequency hearing extends far above that of humans, but horses may be less able to localize the point of origin of brief sounds. The horse's capacity for chemoreception and its reliance on chemical information for identification may more closely resemble that of the dog than of the human. Its tactile sensitivity is high, and the ability of its brain and body to regulate pain perception appears to be similar to that found in other mammals. There is room for a great deal of future research in both the area of equine perception and sensory-based cognition, but for the present time persons interacting with this animal should be made aware of the importance of the sounds they make, the movements of their bodies, the way they touch the animal, and the odors they emit or carry on their clothing.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 400  
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