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Hothersall, B., & Nicol, C. (2007). Equine learning behaviour: accounting for ecological constraints and relationships with humans in experimental design. Behav. Process., 76(1), 45–48.
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Hanggi, E. B., & Ingersoll, J. F. (2009). Stimulus discrimination by horses under scotopic conditions. Behav. Process., 82(1), 45–50.
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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Leblanc, M. - A., & Duncan, P. (2007). Can studies of cognitive abilities and of life in the wild really help us to understand equine learning? Behav. Process., 76, 49–52.
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Linklater, W. L. (2007). Equine learning in a wider context--Opportunities for integrative pluralism. Behav. Process., 76, 53–56.
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Barnard, C. J., & Luo, N. (2002). Acquisition of dominance status affects maze learning in mice. Behav. Process., 60(1), 53–59.
Abstract: Learning is likely to be costly and thus subject to trade-off with other components of life history. An obvious prediction, therefore, is that investment in learning, and thus learning performance, will vary with individual life history strategy and the reproductive value of the learning outcome. We tested this idea in the context of social dominance in male laboratory mice, using a simple radial maze paradigm to compare the ability of high- and low-ranking male mice to track changing food location. We tested animals in randomly selected pairs before and after establishing aggressive rank relationships to distinguish intrinsic differences in learning ability from those attributable to acquiring high or low rank. There was no difference in learning between later dominants and subordinates prior to establishing rank relationships. After pairing, however, dominants showed a significantly greater percentage of correct responses, with the difference being greatest earlier in a sequence of trials. The percentage of correct responses also increased with the amount of aggression initiated during pairing. The results thus appeared to reflect a state-dependent change in learning associated with the aggressive social relationships formed during pairing.
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Krueger, K., Schneider, G., Flauger, B., & Heinze, J. (2015). Context-dependent third-party intervention in agonistic encounters of male Przewalski horses. Behav. Process., 121, 54–62.
Abstract: Abstract One mechanism to resolve conflict among group members is third party intervention, for which several functions, such as kin protection, alliance formation, and the promotion of group cohesion have been proposed. Still, empirical research on the function of intervention behaviour is rare. We studied 40 cases of intervention behaviour in a field study on 13 semi-wild bachelor horses (Equus ferus przewalskii) in (a) standard social situations, and (b) when new horses joined the group (i.e. introductions). Only interventions in agonistic encounters were analysed. Eight of 13 animals directed intervention behaviour toward threatening animal in agonistic encounters of group members. One stallion was particularly active. The stallions did not intervene to support former group mates or kin and interventions were not reciprocated. In introduction situations and in standard social situations, the interveners supported animals which were lower in rank, but targeted, threatening animals of comparable social rank. After introductions, stallions received more affiliative behaviour from animals they supported and thus appeared to intervene for alliance formation. In standard social situations, interveners did not receive more affiliative behaviour from animals they supported and may primarily have intervened to promote group cohesion and to reduce social disruption within the group.
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Ord, T. J., & Evans, C. S. (2002). Interactive video playback and opponent assessment in lizards. Behav. Process., 59(2), 55–65.
Abstract: Video playback has been used to explore many issues in animal communication, but the scope of this work has been constrained by the lack of stimulus-subject interaction. In many natural contexts, each participant's signalling behaviour is dependent from moment-to-moment on that of the other. Analyses of acoustic communication demonstrate the value of reproducing such social contingencies. We assessed the utility of interactive playback for studies of visual signalling by comparing the responses of male Jacky dragons, Amphibolurus muricatus, to interactive and non-interactive digital video playbacks of a life-sized conspecific. Displays produced by lizards in the interactive condition had the effect of suppressing the aggressive display of their simulated opponent. Each stimulus sequence generated during an interactive playback was subsequently played to a size-matched control animal. Males that could interact with the video stimulus responded principally with aggressive displays, while those that could not produced a mixture of aggressive and appeasement signals. Adding a degree of receiver responsiveness is hence sufficient to alter the type of signal evoked, even when video stimuli are physically identical. Interactive playback permits the experimental study of a broader range of theoretical topics and can enhance the realism of video stimuli.
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Briard, L., Deneubourg, J. - L., & Petit, O. (2017). How stallions influence the dynamic of collective movements in two groups of domestic horses, from departure to arrival. Behav. Process., 142, 56–63.
Abstract: Abstract The role of leader in polygynous species has been solely attributed to the male for some time, but recent studies shown decision making to be distributed within the group. However, the specific reproductive strategy and behavioural repertoire of males in polygynous species such as horses may mean that these individuals still have the potential to play a specific role during decision-making. To investigate this subject, we thoroughly studied the behaviour of two domestic stallions during collective movements of their group. We found that they initiated rarely and sometimes failed to recruit the entire group. When departing as followers, they did not accelerate the joining process. Both stallions preferentially occupied the rear position and exhibited numerous monitoring behaviours. Herding behaviours were performed by only one stallion and mostly occurred outside movement context. Finally, we removed this herding stallion from its group to evaluate how the group dynamic changed. As a result, half of the collective movements were five times slower and mares were more dispersed in comparison when the stallion was in the group. Overall, our results suggest that, the two stallions maintained their role of group monitors from departure to arrival. Their influence on the movement dynamic was indirect and did not play a specific role in the process of decision making.
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Murphy, J., & Arkins, S. (2007). Synthesizing what we know of equine learning behaviour. Behav. Process., 76, 57–60.
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Schloegl, C., Kotrschal, K., & Bugnyar, T. (2008). Modifying the object-choice task: Is the way you look important for ravens? Behav. Process., 77(1), 61–65.
Abstract: Most animals seem to have difficulties in using gaze cues to find hidden food in object-choice tasks. For instance, chimpanzees usually fail in these tests, even though they are capable of following other's gaze geometrically behind barriers. Similar to chimpanzees, common ravens are skilled in tracking other's gaze but fail in object-choice tasks. We here explored whether procedural modifications, which had been used successfully in chimpanzees, would also yield positive results in ravens. In our modifications (a) the experimenter approached the cup while gazing at it, (b) the gaze cue was accompanied by a sound and (c) the experimenter could actually see the food while giving the gaze cue. Two out of seven birds performed above chance level in some of these conditions. However, we ascribe this improvement to the individuals' learning ability rather than to an understanding of the communicative nature of the task. This interpretation is further supported by results of a follow-up experiment suggesting that ravens may not rely on conspecifics' gaze cues for finding food caches in a natural foraging context. In sum, our results suggest that ravens may not transfer their gaze follow abilities to foraging situations involving hidden food.
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