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Author (up) 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 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  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5621  
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Author (up) Hanggi, E.B.; Ingersoll, J.F. url  doi
openurl 
  Title Long-term memory for categories and concepts in horses (Equus caballus) Type Journal Article
  Year 2009 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 13 Issue 3 Pages 451-462  
  Keywords Horse – Long-term memory – Concept – Categorization – Discrimination – LCD display – Equine  
  Abstract Three horses (Equus caballus) with a history of performing cognitive tasks including discrimination learning, categorization, and concept use were tested to evaluate their long-term memory (LTM) in three experiments. In addition, use of LCD multi-displays for stimulus presentation was incorporated into cognition testing protocol for the first time with horses. Experiment 1 tested LTM for discrimination learning that originally occurred 6 years earlier. Five sets of stimuli were used and the two horses tested showed no decrement in performance on four of the sets; however, both horses did score below chance on one set. Experiment 2 examined long-term categorization recall 10 years after horses had demonstrated the ability to make stimulus selections based on shared characteristics within a given category. The horse tested for LTM after the decade-long interval immediately and consistently applied the previously learned categorization rule to not only familiar but also novel sets of stimuli. Experiment 3 tested another horse for LTM for a relative size concept. This horse had originally demonstrated concept rule use in order to select stimuli based on their relative size to one another. More than 7 years later and without further training, this horse reliably applied the previously established size concept to both familiar and novel sets of stimuli. These findings are the first reports of long-term categorical and conceptual memory in horses and are consistent with observations of domestic and wild horses, which indicate that behavioral and ecological events may be remembered for long periods of time. These studies also demonstrate the adaptive nature of horses with regard to their ability to generalize over several different testing conditions.  
  Address Equine Research Foundation, P.O. Box 1900, Aptos, CA, 95001, USA, EquiResF@aol.com  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1435-9456 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:19148689 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4760  
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Author (up) 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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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0376-6357 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5051  
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Author (up) Hanggi, E.B.; Ingersoll, J.F.; Waggoner, T.L. doi  openurl
  Title Color vision in horses (Equus caballus): deficiencies identified using a pseudoisochromatic plate test Type Journal Article
  Year 2007 Publication Journal of Comparative Psychology Abbreviated Journal J. Comp. Psychol.  
  Volume 121 Issue 1 Pages 65-72  
  Keywords Animals; Appetitive Behavior; *Color Perception; Color Perception Tests/veterinary; *Discrimination Learning; Female; Horses/*psychology; Male; Sensitivity and Specificity  
  Abstract In the past, equine color vision was tested with stimuli composed either of painted cards or photographic slides or through physiological testing using electroretinogram flicker photometry. Some studies produced similar results, but others did not, demonstrating that there was not yet a definitive answer regarding color vision in horses (Equus caballus). In this study, a pseudoisochromatic plate test--which is highly effective in testing color vision both in small children and in adult humans--was used for the first time on a nonhuman animal. Stimuli consisted of different colored dotted circles set against backgrounds of varying dots. The coloration of the circles corresponded to the visual capabilities of different types of color deficiencies (anomalous trichromacy and dichromacy). Four horses were tested on a 2-choice discrimination task. All horses successfully reached criterion for gray circles and demonstration circles. None of the horses were able to discriminate the protan-deutan plate or the individual protan or deutan plates. However, all were able to discriminate the tritan plate. The results suggest that horses are dichromats with color vision capabilities similar to those of humans with red-green color deficiencies.  
  Address Equine Research Foundation, Aptos, CA 95001, USA. EquiResF@aol.com  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0735-7036 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:17324076 Approved no  
  Call Number refbase @ user @ ; Equine Behaviour @ team @ room B 3.029 Serial 1972  
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