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Soproni, K., Miklósi, Á., Topál, J., & Csányi, V. (2002). Dogs' (Canis familiaris) responsiveness to human pointing gestures. J Comp Psychol, 116(1), 27–34.
Abstract: In a series of 3 experiments, dogs (Canis familiaris) were presented with variations of the human pointing gesture: gestures with reversed direction of movement, cross-pointing, and different arm extensions. Dogs performed at above chance level if they could see the hand (and index finger) protruding from the human body contour. If these minimum requirements were not accessible, dogs still could rely on the body position of the signaler. The direction of movement of the pointing arm did not influence the performance. In summary, these observations suggest that dogs are able to rely on relatively novel gestural forms of the human communicative pointing gesture and that they are able to comprehend to some extent the referential nature of human pointing.
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Langbein, J., Nurnberg, G., Puppe, B., & Manteuffel, G. (2006). Self-Controlled Visual Discrimination Learning of Group-Housed Dwarf Goats (Capra hircus): Behavioral Strategies and Effects of Relocation on Learning and Memory. J. Comp. Psychol., 120(1), 58–66.
Abstract: In most studies on animal learning, individual animals are tested separately in a specific learning environment and with a limited number of trials per day. An alternative approach is to test animals in a familiar environment in their social group. In this study, the authors--applying a fully automated learning device--investigated voluntary, self-controlled visual shape discrimination learning of group-housed dwarf goats (Capra hircus). The majority of the tested goats showed successful shape discrimination, which indicates the adaptive value of an effective learning strategy. However, in each group, a few individual goats developed behavioral strategies different from shape discrimination to get reward. Relocation impairs memory retrieval (probably by attention shifting) only temporarily for previously learnt shapes. The results demonstrate the usefulness of a self-controlled learning paradigm to assess learning abilities of social species in their normal social settings. This may be especially relevant for captive animals to improve their welfare.
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Hanggi, E. B., Ingersoll, J. F., & Waggoner, T. L. (2007). Color vision in horses (Equus caballus): deficiencies identified using a pseudoisochromatic plate test. J. Comp. Psychol., 121(1), 65–72.
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.
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Dorrance, B. R., & Zentall, T. R. (2002). Imitation of conditional discriminations in pigeons (Columba livia). J Comp Psychol, 116(3), 277–285.
Abstract: In the present experiments, the 2-action method was used to determine whether pigeons could learn to imitate a conditional discrimination. Demonstrator pigeons (Columba livia) stepped on a treadle in the presence of 1 light and pecked at the treadle in the presence of another light. Demonstration did not seem to affect acquisition of the conditional discrimination (Experiment 1) but did facilitate its reversal of the conditional discrimination (Experiments 2 and 3). The results suggest that pigeons are not only able to learn a specific behavior by observing another pigeon, but they can also learn under which circumstances to perform that behavior. The results have implications for proposed mechanisms of imitation in animals.
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Baragli, P., Vitale, V., Paoletti, E., Mengoli, M., & Sighieri, C. (2011). Encoding the Object Position for Assessment of Short Term Spatial Memory in Horses (Equus caballus). International Journal of Comparative Psychology, 24(3).
Abstract: In this study, the detour problem was combined with the classic delayed-response task to investigate equine short-term spatial memory. Test subjects were eight female horses, divided into two groups (A and B) of four subjects each. The motivating object was made to move and disappear behind one oftwo identical obstacles in a two-point-choice apparatus. After a 10 s (Group A) or 30 s (Group B) delay the animal was released to seek the object. Both groups made more correct (14.8 ± 1.3 forGroup A and 13.5 ± 3.1 for Group B, mean ± SD) than incorrect choices (5.3 ± 1.3 for Group A and6.5 ± 3.1 for Group B, mean ± SD) and the performance of each group was significantly above chance level (z = 4.14, p = 0.000, for Group A and z = 3.02, p = 0.002, for Group B). Therefore, tested animals were able to recover the object by approaching the correct obstacle after 10 s or 30 s delays, showing that they had encoded and recovered from memory the existence of the target object and its location.
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Stoinski, T. S., & Whiten, A. (2003). Social learning by orangutans (Pongo abelii and Pongo pygmaeus) in a simulated food-processing task. J Comp Psychol, 117(3), 272–282.
Abstract: Increasing evidence for behavioral differences between populations of primates has created a resurgence of interest in examining mechanisms of information transfer between individuals. The authors examined the social transmission of information in 15 captive orangutans (Pongo abelii and Pongo pygmaeus) using a simulated food-processing task. Experimental subjects were shown 1 of 2 methods for removing a suite of defenses on an “artificial fruit.” Control subjects were given no prior exposure before interacting with the fruit. Observing a model provided a functional advantage in the task, as significantly more experimental than control subjects opened the fruit. Within the experimental groups, the authors found a trend toward differences in the actual behaviors used to remove 1 of the defenses. Results support observations from the wild implying horizontal transfer of information in orangutans and show that a number of social learning processes are likely to be involved in the transfer of knowledge in this species.
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de Waal, F. B. (1996). Macaque social culture: development and perpetuation of affiliative networks. J Comp Psychol, 110(2), 147–154.
Abstract: Maternal affiliative relations may be transmitted to offspring, similar to the way in which maternal rank determines offspring rank. The development of 23 captive female rhesus monkeys (Macaca mulatta) was followed from the day of birth until adulthood. A multivariate analysis compared relations among age peers with affiliative relations, kinship, and rank distance among mothers. Maternal relations were an excellent predictor of affiliative relations among daughters, explaining up to 64% of the variance. Much of this predictability was due to the effect of kinship. However, after this variable had been controlled, significant predictability persisted. For relations of female subjects with male peers, on the other hand, maternal relations had no significant predictive value beyond the effect of kinship. One possible explanation of these results is that young rhesus females copy maternal social preferences through a process of cultural learning.
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Weaver, A., & de Waal, F. B. M. (2003). The mother-offspring relationship as a template in social development: reconciliation in captive brown capuchins (Cebus apella). J Comp Psychol, 117(1), 101–110.
Abstract: Mother-offspring (MO) relationship quality was investigated to determine its influence on the development of reconciliation--affiliation between opponents shortly after a fight--because it influenceswhat distressed youngsters learn about calming down. Data were longitudinal and cross-sectional observational samples of 38 MO pairs of monkeys across 24 months. An MO relationship quality index (RQI) classified each pair as secure or insecure. Reconciliation emerged in infancy.Secure youngsters had an appeasing conciliatory style, and insecure youngsters had an agitated conciliatory style. Conclusions are that reconciliation develops from the attachment behavior system and MO RQI is related to the particular conciliatory style youngsters develop by affecting how aroused they are by conflict and the subsequent socializing they seek to calm down.
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Whiten, A., Custance, D. M., Gomez, J. C., Teixidor, P., & Bard, K. A. (1996). Imitative learning of artificial fruit processing in children (Homo sapiens) and chimpanzees (Pan troglodytes). J Comp Psychol, 110(1), 3–14.
Abstract: Observational learning in chimpanzees and young children was investigated using an artificial fruit designed as an analog of natural foraging problems faced by primates. Each of 3 principal components could be removed in 2 alternative ways, demonstration of only one of which was watched by each subject. This permitted subsequent imitation by subjects to be distinguished from stimulus enhancement. Children aged 2-4 years evidenced imitation for 2 components, but also achieved demonstrated outcomes through their own techniques. Chimpanzees relied even more on their own techniques, but they did imitate elements of 1 component of the task. To our knowledge, this is the first experimental evidence of chimpanzee imitation in a functional task designed to simulate foraging behavior hypothesized to be transmitted culturally in the wild.
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Soproni, K., Miklósi, A., Topál, J., & Csányi, V. (2001). Comprehension of human communicative signs in pet dogs (Canis familiaris). J Comp Psychol, 115(2), 122–126.
Abstract: On the basis of a study by D. J. Povinelli, D. T. Bierschwale, and C. G. Cech (1999), the performance of family dogs (Canis familiaris) was examined in a 2-way food choice task in which 4 types of directional cues were given by the experimenter: pointing and gazing, head-nodding (“at target”), head turning above the correct container (“above target”), and glancing only (“eyes only”). The results showed that the performance of the dogs resembled more closely that of the children in D. J. Povinelli et al.'s study, in contrast to the chimpanzees' performance in the same study. It seems that dogs, like children, interpret the test situation as being a form of communication. The hypothesis is that this similarity is attributable to the social experience and acquired social routines in dogs because they spend more time in close contact with humans than apes do, and as a result dogs are probably more experienced in the recognition of human gestures.
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