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Melis, A. P., Hare, B., & Tomasello, M. (2006). Engineering cooperation in chimpanzees: tolerance constraints on cooperation. Anim. Behav., 72(2), 275–286.
Abstract: The cooperative abilities of captive chimpanzees, Pan troglodytes, in experiments do not match the sophistication that might be predicted based on their naturally occurring cooperative behaviours. This discrepancy might partly be because in previous experiments potential chimpanzee cooperators were partnered without regard to their social relationship. We investigated the ability of chimpanzee dyads to solve a physical task cooperatively in relation to their interindividual tolerance levels. Pairs that were most capable of sharing food outside the test were also able to cooperate spontaneously (by simultaneously pulling two ropes) to obtain food. In contrast, pairs that were less inclined to share food outside of the test were unlikely to cooperate. Furthermore, previously successful subjects stopped cooperating when paired with a less tolerant partner, even when the food rewards were presented in a dispersed and divisible form to reduce competition between subjects. These results show that although chimpanzees are capable of spontaneous cooperation in a novel instrumental task, tolerance acts as a constraint on their ability to solve such cooperative problems. This finding highlights the importance of controlling such social constraints in future experiments on chimpanzee cooperation, and suggests that the evolution of human-like cooperative skills might have been preceded by the evolution of a more egalitarian social system and a more human-like temperament.
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Martin, T. I., Zentall, T. R., & Lawrence, L. (2006). Simple discrimination reversals in the domestic horse (Equus caballus): Effect of discriminative stimulus modality on learning to learn. Appl. Anim. Behav. Sci., 101(3-4), 328–338.
Abstract: The cognitive capacity of an organism, relative to that of other species, can be assessed by using a relative measure of learning. One such measure is the ability of an organism to learn about the reversal of a discrimination. The present study compared the performance of two groups of horses on a simple discrimination reversal task when the only difference between the groups was the modality of the relevant cue. For the visual group (absence or presence of a light), the spatial position was irrelevant. For the spatial group, a spatial cue (left/right) was available and the visual cue was irrelevant. Horses in the spatial group learned the original discrimination and six reversals; they also showed evidence of learning to learn. Horses in the visual group did not reach criterion during the study. As a result, there was no evidence of learning to learn.
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McGregor, A., Saggerson, A., Pearce, J., & Heyes, C. (2006). Blind imitation in pigeons, Columba livia. Anim. Behav., 72(2), 287–296.
Abstract: Pigeons that had been trained with a food reward both to peck at and to step on a horizontal plate were allowed to observe a conspecific demonstrator pecking at or stepping on the plate before a test in which the observers were not rewarded for either pecking or stepping. In experiment 1, the demonstrators were not rewarded while being observed. In spite of this, the observers provided evidence of imitation: those that had observed pecking made a greater proportion of pecking responses on test than observers of stepping. In experiment 2, each observer was exposed to a pecking or a stepping conspecific on two occasions. On one occasion, the demonstrator received a food reward for each demonstrated response (continuous reinforcement condition), and on the other the demonstrator's responses were rewarded only rarely (variable interval condition). The observers provided equally strong evidence of imitation in each of these conditions; on test, they made proportionally more of the observed response both when the demonstrators had been richly rewarded and when they had been rarely rewarded. These results show that pigeons engage in `blind' imitation, that is, their imitative behaviour is not always guided by observational learning about response outcomes.
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Kelly, C. D. (2006). Fighting for harems: assessment strategies during male-male contests in the sexually dimorphic Wellington tree weta. Anim. Behav., 72(3), 727–736.
Abstract: Females often aggregate at particular sites for feeding or shelter, thus giving adult males the opportunity to defend harems and increase male reproductive success. Rival males compete for control of harems via ritualized displays or direct combat using weaponry. Contests for harems or the resources required by females can be settled based on asymmetries in fighting ability or resource ownership. Males that accurately assess a rival's fighting ability prior to engaging in potentially costly combat should be favoured by selection. Game theory and optimality models provide three models to explain how individuals decide to persist in or flee from a fight. These models are the energetic war of attrition, the sequential assessment model and the cumulative assessment model. Using staged contests in the laboratory, I tested predictions of these models using the Wellington tree weta, Hemideina crassidens, a sexually dimorphic insect native to New Zealand. Male H. crassidens use their enlarged mandibles as weapons in fights for access to adult females that reside in cavities in trees. My results supported a prediction common to each assessment model: contest duration was negatively correlated with the asymmetry in opponent's weapon size. The sequential assessment model of contest settlement was partially supported but the strongest support was for the cumulative assessment model. Predictions of the latter model were supported because: (1) fights are apparently settled based on own-size assessment; (2) fights occur in a single phase and escalate; and (3) contests involve physical combat and injury. I suggest that, in nocturnal species, cumulative assessment will generally be most applicable.
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Heitor, F., do Mar Oom, M., & Vicente, L. (2006). Social relationships in a herd of Sorraia horses: Part II. Factors affecting affiliative relationships and sexual behaviours. Behav. Process., 73(3), 231–239.
Abstract: The influence of age, dominance rank, kinship and aggressiveness over affiliative relationships and sexual behaviours were analysed in a herd of Sorraia horses, Equus caballus, kept under extensive management. Subjects were 10 adult mares 5-18 years old that had known each other since birth, and a stallion introduced into the group for breeding for the first time. Kinship coefficient and dominance rank were the most important factors affecting affiliative relationships. Bonds were reciprocal and stronger among mares with higher kinship. Mares spent more time in proximity to close-ranking and lower-ranking females. Mares with stronger affiliative relationships or higher relatedness were not less aggressive towards each other. Affiliative relationships between the stallion and the mares were not reciprocal: lower-ranking mares formed stronger bonds with the stallion but he preferred the less genetically related mares for proximity. However, the stallion was involved in sexual behaviours more frequently with the mares that were more genetically related to him. These results suggest that kinship beyond close relatives may affect affiliative relationships both among familiar and among unfamiliar horses. However, the influence of kinship does not imply that horses possess a kin recognition system and alternative explanations are discussed.
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Huebener, E. (2006). Das Niederlegen, Wälzen und Aufspringen des Pferdes. Tierärztl. Umschau, 7, 347–349.
Abstract: Zusammenfassung
Anhand einer Fotofolge werden die Bewegungsabläufe beim Niederlegen, beim Wälzen und beim Wieder-Aufspringen des Pferdes und der dafür erforderliche Einsatz des Balancierstabs Pferde-Kopf und -Hals erläutert. Gründe fürs Niederlegen und Wälzen und Nutzanwendungen der Kenntnis damit verbundener Bewegungsabläufe werden gestreift.
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Huebener, E. (2006). Wie sich der pferdgerechte “selbsttätige Schenkel” besser vermitteln ließe;. Tierärztl. Umschau, 8, 403–406.
Abstract: Von der Basis bis zum Spitzensport werden Pferde gewaltsam zum “Gehorsam” gebracht oder zur Ausführung von Übungen gezwungen. Aktionen gegen die “Rollkur” oder “Hyperflexion” füllen die Medien. Aber die Wurzel des Übels liegt viel tiefer. Die Grundlage kultivierten Reitens in hoher Harmonie zwischen Mensch und Pferd ist eine feinfühlige, nahezu unsichtbare Hilfengebung, für die Bewegungen des Pferderückens und des Pferderumpfes den Zeitgeber liefern. Das Wissen darum in der Reiterwelt zu verankern, ist noch immer nicht gelungen.
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Huebener, E. (2006). The Rider's Impacts and Their Timers – Example: Rider's Aids for Transitions Between Different Gaits. Tierärztl. Umschau, 10, 515–532.
Abstract: The scientific investigation of the basics of the inherited riding teachings assists in conserving its values. Riding instructors should be able to teach not only “how” but also “why”.
The classic European riding teachings that have developed across the centuries are based on perceptions that have their roots in natural phenomena. They are being mirrored, for instance, in the aids to stimulate the change from one gait to the next.
The movements of the horse's trunk and back provide timers for horse-friendly, sensitive aids that create attentive, diligent and happily cooperating horses.
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Huebener, E. (2006). Einwirkungen des Reiters nach Zeitgeber ? Beispiel: Hilfen für Übergänge von einer Gangart in eine andere;. Tierärztl. Umschau, 10, 515–532.
Abstract: Zusammenfassung
Wissenschaftliches Erfassen von Grundlagen der ererbten Reitlehre hilft, deren Werte zu bewahren. Und Reiten Lehrende dürfen nicht nur das “Wie”, sie sollten auch das “Weshalb” vermitteln können.
Die Grundlagen der in Jahrhunderten entstandenen klassischen europäischen Reitlehre beruhen auf der Natur abgelauschten Erkenntnissen. Sie spiegeln sich u. a. in den Hilfen für Übergänge aus einer Gangart in eine andere.
Die Bewegungen von Pferderumpf und -rücken liefern den Zeitgeber für jene pferdgerechte, feinfühlige Hilfengebung, die aufmerksam, fleißig und freudig mitarbeitende Pferde schafft.
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Huebener, E. (2006). How the Horse-Appropriate “Self-Acting” Leg Aid Could Be Better Communicated. Tierärztl. Umschau, 8, 403.
Abstract: From the base to the top of the sport horses are being coerced into “obedience” or the performance of exercises by force. Campaigns against the “Rollkur” or “Hyperflexion” fill the media. However the root of evil lies a lot deeper. The base of cultured riding in high harmony between horse and rider are sensitive, almost invisible aids which are being timed by the movements of the horse's back and trunk. Anchoring the knowledge of this interrelation in rider's minds has to this day been unsuccessful.
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