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Viscido, S.V.; Miller, M.; Wethey, D.S. |
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Title |
The response of a selfish herd to an attack from outside the group perimeter |
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Year |
2001 |
Publication |
Journal of theoretical biology |
Abbreviated Journal  |
J. Theor. Biol. |
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Volume |
208 |
Issue |
3 |
Pages |
315-328 |
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Keywords |
Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior |
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Abstract |
According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation. |
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Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu |
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0022-5193 |
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PMID:11207093 |
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refbase @ user @ |
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555 |
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Gibbs, P.G.; Cohen, N.D. |
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Title |
Early management of race-bred weanlings and yearlings on farms |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Equine Veterinary Science |
Abbreviated Journal |
J. Equine Vet. Sci. |
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Volume |
21 |
Issue |
6 |
Pages |
279-283 |
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Keywords |
Equine, management, growth, nutrition, marketing |
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Abstract |
A total of 58 Thoroughbred and Quarter Horse farms
that managed 1,987 weanlings and yearlings responded to
a survey designed to better characterize early management
of racing prospects. Average age at weaning was 5.5 months
and over half of all farms kept almost three-fourths of all
weanlings to be placed in pre-race training. Variation in
feeding practices was evident and while well over half
of all farms provided balanced nutrient supply to young
horses, 20% to 40% likely fed unbalanced diets. An obvious
preference existed for semi-confinement in young horses
with plenty of free exercise. The majority of farms reported
that young prospects were fed and managed for a moderate
rate of growth. Forced exercise occurred to a much larger
extent with yearlings than weanlings and 40% of farms
described the footing as soft, but not deep. Response to the
prevalence of developmental orthopedic diseases appeared
somewhat guarded, and average injury rate was low on
farms that attributed much of injury to horses playing too
hard. Technological advancements such as photoperiod
manipulation in broodmares were widely used, while
valuable tools such as body condition scoring were utilized
to a lesser extent. |
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Equine Behaviour @ team @ |
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5758 |
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Hostetter, A.B.; Cantero, M.; Hopkins, W.D. |
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Title |
Differential use of vocal and gestural communication by chimpanzees (Pan troglodytes) in response to the attentional status of a human (Homo sapiens) |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Comparative Psychology |
Abbreviated Journal |
J. Comp. Psychol. |
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Volume |
115 |
Issue |
4 |
Pages |
337-343 |
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Keywords |
Animals; *Attention; *Communication Methods, Total; Female; *Gestures; Humans; Male; Motivation; Pan troglodytes/*psychology; Social Environment; Species Specificity; *Vocalization, Animal |
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Abstract |
This study examined the communicative behavior of 49 captive chimpanzees (Pan troglodytes), particularly their use of vocalizations, manual gestures, and other auditory- or tactile-based behaviors as a means of gaining an inattentive audience's attention. A human (Homo sapiens) experimenter held a banana while oriented either toward or away from the chimpanzee. The chimpanzees' behavior was recorded for 60 s. Chimpanzees emitted vocalizations faster and were more likely to produce vocalizations as their 1st communicative behavior when a human was oriented away from them. Chimpanzees used manual gestures more frequently and faster when the human was oriented toward them. These results replicate the findings of earlier studies on chimpanzee gestural communication and provide new information about the intentional and functional use of their vocalizations. |
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Department of Psychology, Berry College, USA |
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0735-7036 |
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PMID:11824896 |
Approved |
yes |
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Call Number |
Equine Behaviour @ team @ |
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4970 |
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Author |
Bahloul, K.; Pereladova, O.B.; Soldatova, N.; Fisenko, G.; Sidorenko, E.; Sempere, A.J. |
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Title |
Social organization and dispersion of introduced kulans (Equus hemionus kulan) and Przewalski horses (Equus przewalski) in the Bukhara Reserve, Uzbekistan |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Arid Environments |
Abbreviated Journal |
J. Arid. Environ. |
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Volume |
47 |
Issue |
3 |
Pages |
309-323 |
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Keywords |
Przewalski horses; kulans; Central Asia; home range; behaviour |
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Abstract |
Asiatic wild asses and Przewalski horses initially inhabited steppe, semi-desert and desert areas, but Przewalski horses became extinct in the wild, and kulans disappeared at the beginning of the 20th century, except for a small population in Turkmenistan. The Bukhara Breeding Centre (Uzbekistan) was created in 1976 for reintroduction and conservation of wild ungulate species. In 1977-1978, five kulans (two males and three females), from Barsa-Kelmes island on the Aral sea, were introduced into the reserve. The group increased to 25-30 animals in 1989-1990, when eight Przewalski horses from Moscow and St Petersburg zoos were introduced. We analysed the home ranges, preferred habitats and social interactions of these closely related species during 1995-1998 by seasonal and group composition. Horses and asses formed a reproductive group and a secondary non-reproductive group. The home range of the secondary group was larger than the reproductive group and seemed to be less dependent from the watering places. Przewalski horses were less adapted to semi-desert conditions (both water and vegetation needs) than kulan. |
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refbase @ user @ |
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777 |
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Author |
Carroll, J.; Murphy, C.J.; Neitz, M.; Hoeve, J.N.; Neitz, J. |
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Title |
Photopigment basis for dichromatic color vision in the horse |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of Vision |
Abbreviated Journal |
J Vis |
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Volume |
1 |
Issue |
2 |
Pages |
80-87 |
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Keywords |
Adaptation, Physiological; Animals; Color Perception/*physiology; Cones (Retina)/chemistry/*physiology; Electroretinography; Horses/*physiology; Photic Stimulation; Phototransduction/physiology; Retinal Pigments/analysis/*physiology; Visual Perception/physiology |
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Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species. |
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Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA |
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1534-7362 |
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PMID:12678603 |
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Equine Behaviour @ team @ |
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4060 |
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Author |
Budras, K.D.; Scheibe, K.; Patan, B.; Streich, W.J.; Kim, K. |
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Title |
Laminitis in Przewalski horses kept in a semireserve |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Veterinary Science (Suwon-si, Korea) |
Abbreviated Journal |
J Vet Sci |
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2 |
Issue |
1 |
Pages |
1-7 |
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Animals; Animals, Domestic; Animals, Wild; Body Weight; Climate; Geography; Horse Diseases/*epidemiology; Horses; Korea/epidemiology; Lameness, Animal/*epidemiology |
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Abstract |
Semireserves were created by the European Conservation Project for scientific research in preparation for reintroduction in the wilderness. They are defined as enclosures large enough to carry a group of Przewalski horses throughout the year without any additional feeding. The semireserve offers diverse opportunities for significant scientific research. As part of a general screening program, the hoof development in a group of Przewalski horses was investigated in the semireserve Schorfheide near Berlin. Since the foundation of this semireserve in 1992, veterinary treatment was not necessary with the exception of hoof trimming in two animals in 1993. However, major health problems were encountered in the spring of 1999, when three other mares showed signs of laminitis. The initial diagnosis by the authors and the local veterinary surgeon based on observation of behaviour, gait, stance, walk and trot of three mares whose initial weights were higher than those of the healthy mares. The initial diagnosis was confirmed by palpation and the occurrence of very deep horn rings on all hooves and a laminitic horn ring on the right front hoof of one mare. An adequate laminitic therapy was not possible under the conditions of a semireserve. The applied management aimed at two goals: 1. To reduce endotoxin production and acidosis in the horses by reducing the ingestion of carbohydrate rich food. 2. To reduce the mares level of activity and to prevent tearing of the suspensory apparatus of the coffin bone. To achieve these two goals it was decided to remove the three laminitic mares from the rich pasture in the main part of the semireserve and to confine them onto the poorer pasture of the small separately fenced area. All three affected mares had fully recovered from their laminitic condition. Prevention of grass laminitis can be achieved by the following measures: 1. Reduction in grass intake could be achieved by increasing the grazing pressure by an increase in stocking rate of the horses or mixed grazing with another species such as sheep. 2. A longer term solution to the problem may well be to sow specific varieties of grass with lower concentrations of water soluble carbohydrate. |
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Institute of Veterinary Anatomy of the Free University of Berlin, Berlin 33, Germany. budras@vetmed.fu-berlin.de |
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1229-845X |
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PMID:14614287 |
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1905 |
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Author |
Kelly, D.M.; Spetch, M.L. |
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Title |
Pigeons encode relative geometry |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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Volume |
27 |
Issue |
4 |
Pages |
417-422 |
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Keywords |
Animals; Behavior, Animal/physiology; Cognition/*physiology; Columbidae; Discrimination Learning/physiology; Form Perception/*physiology; Space Perception/*physiology |
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Abstract |
Pigeons were trained to search for hidden food in a rectangular environment designed to eliminate any external cues. Following training, the authors administered unreinforced test trials in which the geometric properties of the apparatus were manipulated. During tests that preserved the relative geometry but altered the absolute geometry of the environment, the pigeons continued to choose the geometrically correct corners, indicating that they encoded the relative geometry of the enclosure. When tested in a square enclosure, which distorted both the absolute and relative geometry, the pigeons randomly chose among the 4 corners, indicating that their choices were not based on cues external to the apparatus. This study provides new insight into how metric properties of an environment are encoded by pigeons. |
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Department of Psychology, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9. kelly@bio.psy.ruhr-uni-bochum.de |
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0097-7403 |
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PMID:11676090 |
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Equine Behaviour @ team @ |
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2770 |
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Author |
Nakamura, K. |
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Title |
Perseverative errors in object discrimination learning by aged Japanese monkeys (Macaca fuscata) |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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Volume |
27 |
Issue |
4 |
Pages |
345-353 |
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Age Factors; Animals; Behavior, Animal/physiology; Cognition Disorders/*diagnosis/*physiopathology; Discrimination Learning/*physiology; Frontal Lobe/*physiopathology; Macaca; Neuropsychological Tests |
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Abstract |
To examine the nature of age-dependent cognitive decline, performance in terms of concurrent object discriminations was assessed in aged and nonaged Japanese monkeys (Macaca fuscata). Aged monkeys required more sessions and committed more errors than nonaged ones in the discriminations, even in simple object discriminations. Analyses of errors suggest that aged monkeys repeated the same errors and committed more errors when they chose a negative object at the 1st trial. A hypothesis analysis of behavior suggests that their incorrect choices were mainly due to object preference. Therefore, the impairment was probably caused by a failure to inhibit inappropriate responses. Together with previous neuropsychological findings, deficits of aged monkeys in the performance of object discriminations can be explained by dysfunction of the frontal cortex. |
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Department of Behavioral and Brain Sciences, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan. knakamur@pri.kyoto-u.ac.jp |
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0097-7403 |
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PMID:11676085 |
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Equine Behaviour @ team @ |
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2771 |
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Fagot, J.; Wasserman, E.A.; Young, M.E. |
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Title |
Discriminating the relation between relations: the role of entropy in abstract conceptualization by baboons (Papio papio) and humans (Homo sapiens) |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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27 |
Issue |
4 |
Pages |
316-328 |
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Animals; Behavior, Animal; Choice Behavior; Cognition/physiology; *Discrimination (Psychology); Discrimination Learning; *Entropy; Female; Humans; Judgment/*physiology; Male; Papio |
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Two baboons (Papio papio) successfully learned relational matching-to-sample: They picked the choice display that involved the same relation among 16 pictures (same or different) as the sample display, although the sample display shared no pictures with the choice displays. The baboons generalized relational matching behavior to sample displays created from novel pictures. Further experiments varying the number of sample pictures and the mixture of same and different sample pictures suggested that entropy plays a key role in the baboons' conceptual behavior. Two humans (Homo sapiens) were similarly trained and tested; their behavior was both similar to and different from the baboons' behavior. The results suggest that animals other than humans and chimpanzees can discriminate the relation between relations. They further suggest that entropy detection may underlie same-different conceptualization, but that additional processes may participate in human conceptualization. |
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Comparative Cognition Research Group, Center for Research in Cognitive Neurosciences, 31 Chemin Joseph Aiguier, 13402 Marseille, France. fagot@lnf.cnrs-mrs.fr |
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0097-7403 |
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PMID:11676083 |
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Equine Behaviour @ team @ |
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2772 |
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Author |
Cavoto, K.K.; Cook, R.G. |
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Title |
Cognitive precedence for local information in hierarchical stimulus processing by pigeons |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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27 |
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1 |
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3-16 |
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Animals; Behavior, Animal; *Cognition; *Columbidae; Conditioning, Operant; Male |
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Four experiments investigated the processing of hierarchical stimuli by pigeons. Using a 4 alternative divided-attention task, 4 pigeons were food-reinforced for accurately identifying letters arranged as either hierarchical global- or local-relevant stimuli or as size-matched filled stimuli. Experiment 1 found that task acquisition was faster with local-relevant than global-relevant stimuli. This difference was not due to letter size. Experiment 2 demonstrated successful transfer to a novel irrelevant letter configuration. Experiments 3 and 4 tested pigeons' responses to conflict probe stimuli composed of equally discriminable relevant letters at each level. These tests revealed that all of the pigeons showed a cognitive precedence for local information early in processing, with the pigeons using different cues to initiate the processing of global information. This local advantage contrasts with previously reported results for humans and pigeons but is similar to that reported for nonhuman primates. Alternatives attempting to reconcile these contrasting comparative results are considered. |
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Department of Psychology, Tufts University, Medford, Massachusetts 02155, USA |
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0097-7403 |
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PMID:11199512 |
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Equine Behaviour @ team @ |
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2773 |
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