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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 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 Lomas, C.A.; Piggins, D.; Phillips, C.J.C. url  doi
openurl 
  Title Visual awareness Type Journal Article
  Year 1998 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 57 Issue 3-4 Pages 247-257  
  Keywords Visual awareness; Colour vision; Rhythm  
  Abstract Awareness varies between different species and humans can never truly appreciate what it is like to be another individual, either of the same species or another. Visual perceptual faculties provide some evidence of the extent to which domesticated animals derive information from objects in their environment, whilst changes in behaviour resulting from different visual stimuli can also provide valuable information on the state of visual awareness. Extensive processing of potentially visual information must occur in all domesticated species, but is much less well understood than purely sensory based information. For example, sensory aspects of colour vision are reasonably well understood, but the role of wavelength variables in an animal's cognition and its colour experience is not clear. Considerable use is made of diurnal changes in photoperiod to synchronise endogenous rhythms to particular times of the day and the year. Variation in light intensity in natural images is also important for social reasons for animals to be able to discriminate between, e.g., different faces, but little is known about intensity preferences or the effects of intensity on behaviour. It appears likely that in many cases visual stimuli represent some of the most important influences on an animal's awareness, either alone or in combination with, e.g., olfactory cues. However, a much greater understanding of their processing is required before we can make useful deductions about visual awareness in domesticated animals.  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4309  
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Author Mech L.D. url  openurl
  Title Leadership in Wolf, Canis lupus, Packs. Type Journal Article
  Year 2000 Publication Canadian Field-Naturalist Abbreviated Journal Can Field Nat  
  Volume 114 Issue 2 Pages 259-263  
  Keywords Wolf, Canis lupus, leadership, behavior, foraging, movements, pup care, provisioning, sociality, reproduction, breeding, Northwest Territories.  
  Abstract I examine leadership in Wolf (Canis lupus) packs based on published observations and data gathered during summers from 1986 to 1998 studying a free-ranging pack of Wolves on Ellesmere Island that were habituated to my presence. The breeding male tended to initiate activities associated with foraging and travel, and the breeding female to initiate, and predominate in, pup care and protection. However, there was considerable overlap and interaction during these activities such that leadership could be considered a joint function. In packs with multiple breeders, quantitative information about leadership is needed.  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4688  
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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 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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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4953  
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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 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 Siniscalchi, M.; Sasso, R.; Pepe, A.M.; Vallortigara, G.; Quaranta, A. url  doi
openurl 
  Title Dogs turn left to emotional stimuli Type Journal Article
  Year 2010 Publication Behavioural Brain Research Abbreviated Journal Behav. Brain. Res.  
  Volume 208 Issue 2 Pages 516-521  
  Keywords Dog; Laterality; Vision; Behaviour; Physiology; Cognition; Emotion; Animal welfare  
  Abstract 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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  ISSN 0166-4328 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5080  
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Author Adler, L.L.; Adler, H.E. url  doi
openurl 
  Title Ontogeny of observational learning in the dog (Canis familiaris) Type Journal Article
  Year 1977 Publication Developmental Psychobiology Abbreviated Journal Dev Psychobiol  
  Volume 10 Issue 3 Pages 267-271  
  Keywords Animals; Dogs/*physiology; Female; Learning/*physiology; Male; Vision, Ocular/physiology  
  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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  ISSN 0012-1630 ISBN Medium  
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  Notes PMID:863122 Approved no  
  Call Number Equine Behaviour @ team @ Serial 5186  
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Author Blackmore, T.L.; Foster, T.M.; Sumpter, C.E.; Temple, W. url  doi
openurl 
  Title An investigation of colour discrimination with horses (Equus caballus) Type Journal Article
  Year 2008 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 78 Issue 3 Pages 387-396  
  Keywords Chromatic discrimination; Colour vision; Horse; Operant  
  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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  ISSN 0376-6357 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5336  
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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 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 Tomkins, L.M.; Williams, K.A.; Thomson, P.C.; McGreevy, P.D. url  doi
openurl 
  Title Sensory Jump Test as a measure of sensory (visual) lateralization in dogs (Canis familiaris) Type Journal Article
  Year 2010 Publication Journal of Veterinary Behavior Abbreviated Journal  
  Volume 5 Issue 5 Pages 256-267  
  Keywords sensory lateralization; monocular vision; binocular vision; jump kinematics; dog  
  Abstract Sensory lateralization in dogs (n = 74) was investigated in this study using our innovation, the Sensory Jump Test. This required the modification of head halters to create three different ocular treatments (binocular, right, and left monocular vision) for eye preference assessment in a jumping task. Ten jumps were recorded as a jump set for each treatment. Measurements recorded included (i) launch and landing paws, (ii) type of jump, (iii) approach distance, (iv) clearance height of the forepaw, hindpaw, and the lowest part of the body to clear the jump, and (v) whether the jump was successful. Factors significantly associated with these jump outcomes included ocular treatment, jump set number, and replication number. Most notably, in the first jump set, findings indicated a left hemispheric dominance for the initial navigation of the Sensory Jump Test, as left monocular vision (LMV) compromised of jumping more than right monocular (RMV) and binocular vision, with a significantly reduced approach distance and forepaw clearance observed in dogs with LMV. However, by the third jump set, dogs undergoing LMV launched from a greater approach distance and with a higher clearance height, corresponding to an increase in success rate of the jump, in comparison with RMV and binocular vision dogs. A marginally non-significant RMV bias was observed for eye preference based on the laterality indices for approach distance (P = 0.060) and lowest body part clearance height (P = 0.067). A comparison between eye preference and launching or landing paws showed no association between these measures of sensory and motor laterality. To our knowledge, this is the first study to report on sensory lateralization in the dog, and furthermore, to compare both motor and sensory laterality in dogs.  
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  ISSN 1558-7878 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ S1558-7878(10)00019-5 Serial 5379  
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