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Brauer, J., Kaminski, J., Riedel, J., Call, J., & Tomasello, M. (2006). Making inferences about the location of hidden food: social dog, causal ape. J Comp Psychol, 120(1), 38–47.
Abstract: Domestic dogs (Canis familiaris) and great apes from the genus Pan were tested on a series of object choice tasks. In each task, the location of hidden food was indicated for subjects by some kind of communicative, behavioral, or physical cue. On the basis of differences in the ecologies of these 2 genera, as well as on previous research, the authors hypothesized that dogs should be especially skillful in using human communicative cues such as the pointing gesture, whereas apes should be especially skillful in using physical, causal cues such as food in a cup making noise when it is shaken. The overall pattern of performance by the 2 genera strongly supported this social-dog, causal-ape hypothesis. This result is discussed in terms of apes' adaptations for complex, extractive foraging and dogs' adaptations, during the domestication process, for cooperative communication with humans.
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Horner, V., & Whiten, A. (2007). Learning from others' mistakes limits on understanding a trap-tube task by young chimpanzees (Pan troglodytes) and children (Homo sapiens). J Comp Psychol, 121(1), 12–21.
Abstract: A trap-tube task was used to determine whether chimpanzees (Pan troglodytes) and children (Homo sapiens) who observed a model's errors and successes could master the task in fewer trials than those who saw only successes. Two- to 7-year-old chimpanzees and 3- to 4-year-old children did not benefit from observing errors and found the task difficult. Two of the 6 chimpanzees developed a successful anticipatory strategy but showed no evidence of representing the core causal relations involved in trapping. Three- to 4-year-old children showed a similar limitation and tended to copy the actions of the demonstrator, irrespective of their causal relevance. Five- to 6-year-old children were able to master the task but did not appear to be influenced by social learning or benefit from observing errors.
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Call J. (2004). Inferences about the location of food in the great apes (Pan paniscus, Pan troglodytes, Gorilla gorilla, and Pongo pygmaeus). J. Comp. Psychol., 118(2), 232.
Abstract: Bonobos (Pan paniscus; n = 4), chimpanzees (Pan troglodytes; n = 12), gorillas (Gorilla gorilla; n = 8), and orangutans (Pongo pygmaeus; n = 6) were presented with 2 cups (1 baited) and given visual or auditory information about their contents. Visual information consisted of letting subjects look inside the cups. Auditory information consisted of shaking the cup so that the baited cup produced a rattling sound. Subjects correctly selected the baited cup both when they saw or heard the food. Nine individuals were above chance in both visual and auditory conditions. More important, subjects as a group selected the baited cup when only the empty cup was either shown or shaken, which means that subjects chose correctly without having seen or heard the food (i.e., inference by exclusion). Control tests showed that subjects were not more attracted to noisy cups, avoided shaken noiseless cups, or learned to use auditory information as a cue during the study. It is concluded that subjects understood that the food caused the noise, not simply that the noise was associated with the food. (PsycINFO Database Record (c) 2010 APA, all rights reserved)
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Hanggi, E. B. (1999). Categorization Learning in Horses (Equus caballus). J. Comp. Psychol., 113(3), 243–252.
Abstract: Categorization learning was investigated in 2 horses (Equus caballus). Both horses learned to select a 2-dimensional black stimulus with an open center instead of a filled stimulus in a 2-choice discrimination task. After a criterion of 10 out of 10 correct responses in a random series for 2 consecutive sessions was reached, 15 additional pairs of open-center versus filled stimuli were tested. Each was run to criterion and then incorporated into sessions of randomly mixed problems. Both horses solved the 1st problem by simple pattern discrimination and showed evidence of categorical processing for subsequent problems. New pairs were learned with few or no errors, and correct responses on novel trials were significantly above chance. These results suggest that the horses were making their selections on the basis of shared characteristics with the training stimuli and were using categorization skills in problem solving.
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König, H. E., Wissdorf, H., Probst, A., Macher, R., Voß, S., & Polsterer, E. (2005). Considerations about the function of the mimic muscles and the vomeronasal organ of horses during the Flehmen reaction. Pferdeheilkunde, 21(4), 297–300.
Abstract: Additional to the olfactory epithelium, the equine vomeronasal organ serves to the perception of odorous substances and specially for pheromones. In a middle-size horse this organ has an extension in length from an imaginary transverse plane about 10 cm caudally the nostrils to a transverse plane through the middle of the second premolar tooth. During the Flehmen reaction the levator labii superior, nasolabial, caninus and lateralis nasi muscles contract. The upper lip and the tip of the nose are lifted. The opening of the nostrils is narrowed, caused by the convergence of the plate and horn of the alar cartilage. In this manner in case of Flehmen reaction air is directly conducted towards the opening of the vomeronasal organ into the nasal cavity during inspiration. During the “Flehmen” horses assume a characteristic posture.
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Hostetter, A. B., Cantero, M., & Hopkins, W. D. (2001). Differential use of vocal and gestural communication by chimpanzees (Pan troglodytes) in response to the attentional status of a human (Homo sapiens). J. Comp. Psychol., 115(4), 337–343.
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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Pack, A. A., & Herman, L. M. (2004). Bottlenosed Dolphins (Tursiops truncatus) Comprehend the Referent of Both Static and Dynamic Human Gazing and Pointing in an Object-Choice Task. J. Comp. Psychol., 118(2), 160–171.
Abstract: The authors tested 2 bottlenosed dolphins (Tursiops truncatus) for their understanding of human-directed gazing or pointing in a 2-alternative object-choice task. A dolphin watched a human informant either gazing at or pointing toward 1 of 2 laterally placed objects and was required to perform a previously indicated action to that object. Both static and dynamic gaze, as well as static and dynamic direct points and cross-body points, yielded errorless or nearly errorless performance. Gaze with the informant's torso obscured (only the head was shown) produced no performance decrement, but gaze with eyes only resulted in chance performance. The results revealed spontaneous understanding of human gaze accomplished through head orientation, with or without the human informant's eyes obscured, and demonstrated that gaze-directed cues were as effective as point-directed cues in the object-choice task. (PsycINFO Database Record (c) 2009 APA, all rights reserved)
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Shapiro, A. D., Janik, V. M., & Slater, P. J. B. (2003). A gray seal's (Halichoerus grypus) responses to experimenter-given pointing and directional cues. J Comp Psychol, 117(4), 355–362.
Abstract: A gray seal (Halichoerus grypus) was trained to touch a target on its left or right by responding to pointing signals. The authors then tested whether the seal would be able to generalize spontaneously to altered signals. It responded correctly to center pointing and head turning, center upper body turning, and off-center pointing but not to head turning and eye movements alone. The seal also responded correctly to brief ipsilateral and contralateral points from center and lateral positions. Pointing gestures did not cause the seal to select an object placed centrally behind it. Like many animals in similar studies, this gray seal probably did not understand the referential character of these gestures but rather used signal generalization and experience from initial operant conditioning to solve these tasks.
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Hodgson, D., Howe, S., Jeffcott, L., Reid, S., Mellor, D., & Higgins, A. (2005). Effect of prolonged use of altrenogest on behaviour in mares (Vol. 169).
Abstract: Erratum in:
Vet J. 2005 May;169(3):321.
Corrected and republished in:
Vet J. 2005 May;169(3):322-5.
Oral administration of altrenogest for oestrus suppression in competition horses is believed to be widespread in some equestrian disciplines, and can be administered continuously for several months during a competition season. To examine whether altrenogest has any anabolic or other potential performance enhancing properties that may give a horse an unfair advantage, we examined the effect of oral altrenogest (0.044 mg/kg), given daily for a period of eight weeks, on social hierarchy, activity budget, body-mass and body condition score of 12 sedentary mares. We concluded that prolonged oral administration of altrenogest at recommended dose rates to sedentary mares resulted in no effect on dominance hierarchies, body mass or condition score.
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McGreevy, P. D., French, N. P., & Nicol, C. J. (1995). The prevalence of abnormal behaviours in dressage, eventing and endurance horses in relation to stabling. Vet. Rec., 137(2), 36–37.
Abstract: The behaviour of horses competing in different disciplines was studied and the relationship between the time they spent out of the stable and the prevalence of abnormal behaviour was examined. The owners of dressage, eventing and endurance horses were sent a questionnaire and a total of 1101 responses were received, giving data on 1750 horses. The behaviours studied were wood-chewing, weaving, crib-biting/wind-sucking and box-walking. The reported percentage prevalences of abnormal behaviour for the dressage, eventing and endurance horses were 32.5, 30.8 and 19.5, respectively. The relationship between the time spent in the stable and the prevalence of abnormal behaviour was examined by chi 2 tests which showed that there were significant linear trends for the eventing group (P < 0.001) and the dressage group (P < 0.05). It is concluded that the time a horse spends out of the stable is related to the discipline for which it is being trained and in dressage and eventing horses the time spent in a stable is correlated with an increased risk of abnormal behaviour.
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