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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' |
Type |
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 |
384-390 |
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Keywords |
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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Abstract |
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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no |
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Call Number |
refbase @ user @ |
Serial |
836 |
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Author |
van Niekerk, H.P. |
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Title |
Ethological studies within the man-horse relationship |
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Journal Article |
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Year |
1980 |
Publication |
Journal of the South African Veterinary Association |
Abbreviated Journal |
J S Afr Vet Assoc |
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Volume |
51 |
Issue |
4 |
Pages |
237-238 |
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Keywords |
Animals; Behavior, Animal; Hearing; Horses/*physiology; Humans; Smell; Taste; Touch; Vision |
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Abstract |
Certain aspects of ethology and the horse's senses are discussed to bring about a better understanding between man and horse. Furthermore the behaviour of horses with respect to housing, feeding, breeding, veterinary treatment and work are considered. |
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1019-9128 |
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PMID:7241494 |
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refbase @ user @ |
Serial |
1960 |
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Author |
Timney, B.; Keil, K. |
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Title |
Local and global stereopsis in the horse |
Type |
Journal Article |
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Year |
1999 |
Publication |
Vision Research |
Abbreviated Journal |
Vision Res |
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Volume |
39 |
Issue |
10 |
Pages |
1861-1867 |
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Keywords |
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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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. |
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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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Call Number |
Equine Behaviour @ team @ |
Serial |
3580 |
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Author |
Regolin, L.; Marconato, F.; Vallortigara, G. |
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Title |
Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus) |
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Journal Article |
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Year |
2004 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
7 |
Issue |
3 |
Pages |
162-170 |
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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 |
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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. |
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Department of General Psychology, University of Padova, Via Venezia 8, 35131, Padova, Italy. lucia.regolin@unipd.it |
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1435-9448 |
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PMID:15241654 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2519 |
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Author |
Adler, L.L.; Adler, H.E. |
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Title |
Ontogeny of observational learning in the dog (Canis familiaris) |
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Journal Article |
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Year |
1977 |
Publication |
Developmental Psychobiology |
Abbreviated Journal |
Dev Psychobiol |
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Volume |
10 |
Issue |
3 |
Pages |
267-271 |
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Keywords |
Animals; Dogs/*physiology; Female; Learning/*physiology; Male; Vision, Ocular/physiology |
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Abstract |
A split-litter technique was used to test observational learning in 4 litters of Miniature Dachshund puppies, 21, 28, 38, and 60 days old at the beginning of the experiment. In one side of a duplicate cage, one puppy of a litter, the demonstrator, learned to pull in a food cart on a runner by means of a ribbon, while another puppy, the observer, watched from an adjacent compartment, separated by a wire screen. Observational learning was demonstrated by the saving in time for the 1st trial when the observer was given the same problem to solve. Maturation, particularly the development of visual function and motor coordination, set a lower age limit for the emergence of observational learning. |
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0012-1630 |
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Notes |
PMID:863122 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
5186 |
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Author |
Mills, D.S.; Riezebos, M. |
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Title |
The role of the image of a conspecific in the regulation of stereotypic head movements in the horse |
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Journal Article |
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Year |
2005 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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Volume |
91 |
Issue |
1-2 |
Pages |
155-165 |
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Keywords |
Behaviour; Horse; Nodding; Perception; Stereotypy; Vision; Weaving |
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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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no |
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Call Number |
refbase @ user @ |
Serial |
307 |
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Permanent link to this record |
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Author |
Kilian, A.; Fersen, L. von; Güntürkün, O. |
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Title |
Left hemispheric advantage for numerical abilities in the bottlenose dolphin |
Type |
Journal Article |
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Year |
2005 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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Volume |
68 |
Issue |
2 |
Pages |
179-184 |
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Keywords |
Bottlenose dolphin; Hemispheric specialization; Monocular vision; Numerical ability |
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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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0376-6357 |
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Equine Behaviour @ team @ |
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5366 |
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Author |
Blackmore, T.L.; Foster, T.M.; Sumpter, C.E.; Temple, W. |
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Title |
An investigation of colour discrimination with horses (Equus caballus) |
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Journal Article |
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Year |
2008 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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Volume |
78 |
Issue |
3 |
Pages |
387-396 |
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Keywords |
Chromatic discrimination; Colour vision; Horse; Operant |
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Abstract |
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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Author |
Wolfe, J.M. |
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Title |
Hidden visual processes |
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Journal Article |
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Year |
1983 |
Publication |
Scientific American |
Abbreviated Journal |
Sci Am |
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Volume |
248 |
Issue |
2 |
Pages |
94-103 |
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Keywords |
Color Perception/*physiology; Humans; Motion Perception/physiology; Ocular Physiology; Vision; Visual Perception/*physiology |
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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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0036-8733 |
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PMID:6836258 |
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Equine Behaviour @ team @ |
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4066 |
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Author |
Macuda, T.; Timney, B. |
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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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Volume |
44 |
Issue |
3 |
Pages |
301-307 |
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Keywords |
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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refbase @ user @ |
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844 |
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