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Webster, M. M., & Laland, K. N. (2008). Social learning strategies and predation risk: minnows copy only when using private information would be costly. Proc. R. Soc. Lond. B, 275(1653), 2869–2876.
Abstract: Animals can acquire information from the environment privately, by sampling it directly, or socially, through learning from others. Generally, private information is more accurate, but expensive to acquire, while social information is cheaper but less reliable. Accordingly, the 'costly information hypothesis' predicts that individuals will use private information when the costs associated with doing so are low, but that they should increasingly use social information as the costs of using private information rise. While consistent with considerable data, this theory has yet to be directly tested in a satisfactory manner. We tested this hypothesis by giving minnows (Phoxinus phoxinus) a choice between socially demonstrated and non-demonstrated prey patches under conditions of low, indirect and high simulated predation risk. Subjects had no experience (experiment 1) or prior private information that conflicted with the social information provided by the demonstrators (experiment 2). In both experiments, subjects spent more time in the demonstrated patch than in the non-demonstrated patch, and in experiment 1 made fewer switches between patches, when risk was high compared with when it was low. These findings are consistent with the predictions of the costly information hypothesis, and imply that minnows adopt a 'copy-when-asocial-learning-is-costly' learning strategy.
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Krueger, K., & Heinze, J. (2008). Horse sense: social status of horses (Equus caballus) affects their likelihood of copying other horses` behavior. Anim. Cogn., 11(3), 431–439.
Abstract: Animals that live in stable social groups need to gather information on their own relative position in the group`s social hierarchy, either by directly threatening or challenging others, or in a less costly manner, by observing interactions among others. Such indirect inference of dominance relationships has previously been reported from primates, rats, and birds and fish. Here, we show that domestic horses, Equus caballus, are similarly capable of social cognition. Taking advantage of a specific “following behavior” that horses show towards humans in a riding arena, we investigated whether bystander horses adjust their response to an experimenter according to the observed interaction and their own dominance relationship with the horse whose reaction to the experimenter they had observed before. Horses copied the following behavior towards an experimenter after watching a dominant horse following, but did not follow after observing a subordinate horse or a horse from another social group doing so. The following behavior which horses show towards an experimenter therefore appears to be affected by the demonstrator`s behavior and social status relative to the observer.
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Griffin, A. S. (2008). Socially acquired predator avoidance: Is it just classical conditioning? Special Issue:Brain Mechanisms, Cognition and Behaviour in Birds, 76(3), 264–271.
Abstract: Associative learning theories presume the existence of a general purpose learning process, the structure of which does not mirror the demands of any particular learning problem. In contrast, learning scientists working within an Evolutionary Biology tradition believe that learning processes have been shaped by ecological demands. One potential means of exploring how ecology may have modified properties of acquisition is to use associative learning theory as a framework within which to analyse a particular learning phenomenon. Recent work has used this approach to examine whether socially transmitted predator avoidance can be conceptualised as a classical conditioning process in which a novel predator stimulus acts as a conditioned stimulus (CS) and acquires control over an avoidance response after it has become associated with alarm signals of social companions, the unconditioned stimulus (US). I review here a series of studies examining the effect of CS/US presentation timing on the likelihood of acquisition. Results suggest that socially acquired predator avoidance may be less sensitive to forward relationships than traditional classical conditioning paradigms. I make the case that socially acquired predator avoidance is an exciting novel one-trial learning paradigm that could be studied along side fear conditioning. Comparisons between social and non-social learning of danger at both the behavioural and neural level may yield a better understanding of how ecology might shape properties and mechanisms of learning.
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Götz, C. (2008). Praxishandbuch Freispringen: Gymnastik – Training – Abwechslung. Brunsbek: Cadmos Verlag.
Abstract: Aus dem Inhalt:
* Warum Freispringen? * Die Ausstattung * Der Ablauf * Sehen lernen * Freispringen aufbauen * Fehler korrigieren Kurzbeschreibung In vielen größeren Reitställen wird das Freispringen von den dortigen Ausbildern für die untergestellten Pferde angeboten. Doch auch in Eigenregie und auf kleineren Anlagen – sowohl in der Halle als auch auf dem Reitplatz – lässt sich das Freispringen organisieren und durchführen. Es bringt Abwechslung in den Trainingsalltag von Pferden aller Rassen und Reitweisen und hat auch für Pferde, die unter dem Sattel nicht springen müssen, einen hervorragenden gymnastizierenden Effekt. Für Springpferde gehört das Freispringen zu einem durchdachten Trainingskonzept zwingend dazu – lernen sie hierbei doch, Selbstvertrauen und Routine zu gewinnen und ihre Springtechnik zu verbessern. Voraussetzung ist, dass die Menschen, die das Freispringen durchführen, die Hindernisse sachkundig aufbauen, die Pferde richtig vorbereiten und den Ablauf des Freispringens den Fähigkeiten des jeweiligen Kandidaten entsprechend gestalten. Das notwendige Handwerkszeug hierfür liefert ihnen dieses verständlich geschriebene und mit vielen erläuternden Bildern und Bildabfolgen versehene Buch. Über den Autor Claudia Götz, geboren 1965, ist Diplomjournalistin und arbeitet unter anderem als Sachbuchautorin. Als Matrix-Rhythmus-Therapeutin verfügt sie über umfangreiches Wissen rund um Anatomie und Physiologie der Muskulatur und bildet sich zum Beispiel im Bereich Trainingslehre regelmäßig weiter. Die Berittführerin FN und begeisterte Vielseitigkeits- und Freizeitreiterin lebt in der Nähe von Regensburg. |
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Dwan, K., Altman, D. G., Arnaiz, J. A., Bloom, J., Chan, A. - W., Cronin, E., et al. (2008). Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias. Plos One, 3(8), e3081.
Abstract: Background The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention. Methodology/Principal Findings We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40-62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies. Conclusions Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.
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Rands, S. A., Cowlishaw, G., Pettifor, R. A., Rowcliffe, J. M., & Johnstone, R. A. (2008). The emergence of leaders and followers in foraging pairs when the qualities of individuals differ. BMC Evol Biol, 8, 51.
Abstract: BACKGROUND: Foraging in groups offers animals a number of advantages, such as increasing their likelihood of finding food or detecting and avoiding predators. In order for a group to remain together, there has to be some degree of coordination of behaviour and movement between its members (which may in some cases be initiated by a decision-making leader, and in other cases may emerge as an underlying property of the group). For example, behavioural synchronisation is a phenomenon where animals within a group initiate and then continue to conduct identical behaviours, and has been characterised for a wide range of species. We examine how a pair of animals should behave using a state-dependent approach, and ask what conditions are likely to lead to behavioural synchronisation occurring, and whether one of the individuals is more likely to act as a leader. RESULTS: The model we describe considers how the energetic gain, metabolic requirements and predation risks faced by the individuals affect measures of their energetic state and behaviour (such as the degree of behavioural synchronisation seen within the pair, and the value to an individual of knowing the energetic state of its colleague). We explore how predictable changes in these measures are in response to changes in physiological requirements and predation risk. We also consider how these measures should change when the members of the pair are not identical in their metabolic requirements or their susceptibility to predation. We find that many of the changes seen in these measures are complex, especially when asymmetries exist between the members of the pair. CONCLUSION: Analyses are presented that demonstrate that, although these general patterns are robust, care needs to be taken when considering the effects of individual differences, as the relationship between individual differences and the resulting qualitative changes in behaviour may be complex. We discuss how these results are related to experimental observations, and how the model and its predictions could be extended.
Keywords: Animals; *Feeding Behavior; *Food Chain; *Models, Biological; *Social Dominance
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Scheumann, M., & Zimmermann, E. (2008). Sex-specific asymmetries in communication sound perception are not related to hand preference in an early primate. BMC Biology, 6(1), 3.
Abstract: BACKGROUND:Left hemispheric dominance of language processing and handedness, previously thought to be unique to humans, is currently under debate. To gain an insight into the origin of lateralization in primates, we have studied gray mouse lemurs, suggested to represent the most ancestral primate condition. We explored potential functional asymmetries on the behavioral level by applying a combined handedness and auditory perception task. For testing handedness, we used a forced food-grasping task. For testing auditory perception, we adapted the head turn paradigm, originally established for exploring hemispheric specializations in conspecific sound processing in Old World monkeys, and exposed 38 subjects to control sounds and conspecific communication sounds of positive and negative emotional valence.RESULTS:The tested mouse lemur population did not show an asymmetry in hand preference or in orientation towards conspecific communication sounds. However, males, but not females, exhibited a significant right ear-left hemisphere bias when exposed to conspecific communication sounds of negative emotional valence. Orientation asymmetries were not related to hand preference.CONCLUSION:Our results provide the first evidence for sex-specific asymmetries for conspecific communication sound perception in non-human primates. Furthermore, they suggest that hemispheric dominance for communication sound processing evolved before handedness and independently from each other.
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Knubben,, J. M. Knubben, Gygax,, L. Gygax, Auer,, J. Auer, et al. (2008). Häufigkeiten von Erkrankungen und Verletzungen in der Schweizer Pferdepopulation. Schweizer Archiv für Tierheilkunde, 150(8), 399–408.
Abstract: Bei einer für die Schweiz repräsentativ und zufällig ausgewählten Stichprobe von 2912 Pferden und Ponys wurden mittels Fragebogen Daten zum aktuellen Gesundheitszustand und zum Auftreten von Erkrankungen und Verletzungen während der vergangenen 12 Monate erfasst. 718 Pferde (24.7%) wurden im Erfassungszeitraum wegen 897 gesundheitlichen Problemen einem Tierarzt vorgestellt. Orthopädische und traumatische Fälle machten den grössten Anteil aus (41.5%), gefolgt von Erkrankungen des Gastrointestinal- (27.1%) und des Respirationstrakts (14.0%). Die Hälfte der Lahmheiten entstand als unmittelbare Folge einer Verletzung. Die Verletzungen waren assoziiert mit Weidegang/Auslauf (38.1%), Schläge/Bissen durch Artgenossen (21.6%), Stall (7.8%), Gelände (13.4%), Training (3.5%), Wettkampf (3.5%), Transport (3.0%) oder mit anderen Umständen (9.1%). In 26.5% der Kolikfälle wurde im Monat vor der Erkrankung Futterumstellung vorgenommen. Bei den Atmungserkrankungen wurde in 13.8% die gleiche Krankheit auch bei anderen Pferden im Stall diagnostiziert. Bei 8.1% aller Fälle erfolgte eine Operation, 6.7% waren mit einem mehrtägigem Klinikaufenthalt verbunden. Bei 25.6% aller tiermedizinisch diagnostizierten Fälle wurden ergänzend oder ausschliesslich komplementärmedizinische Therapiemethoden eingesetzt.
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Amant, R. S., & Horton, T. E. (2008). Revisiting the definition of animal tool use. Anim. Behav., 75(4), 1199–1208.
Abstract: Benjamin Beck's definition of tool use has served the field of animal cognition well for over 25 years (Beck 1980, Animal Tool Behavior: the Use and Manufacture of Tools, New York, Garland STPM). This article proposes a new, more explanatory definition that accounts for tool use in terms of two complementary subcategories of behaviours: behaviours aimed at altering a target object by mechanical means and behaviours that mediate the flow of information between the tool user and the environment or other organisms in the environment. The conceptual foundation and implications of the new definition are contrasted with those of existing definitions, particularly Beck's. The new definition is informally evaluated with respect to a set of scenarios that highlights differences from Beck's definition as well as those of others in the literature.
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Prather, J. F., Peters, S., Nowicki, S., & Mooney, R. (2008). Precise auditory-vocal mirroring in neurons for learned vocal communication. Nature, 451(7176), 305–310.
Abstract: Brain mechanisms for communication must establish a correspondence between sensory and motor codes used to represent
the signal. One idea is that this correspondence is established at the level of single neurons that are active when the individual performs a particular gesture or observes a similar gesture performed by another individual. Although neurons that display a precise auditory–vocal correspondence could facilitate vocal communication, they have yet to be identified. Here we report that a certain class of neurons in the swamp sparrow forebrain displays a precise auditory–vocal correspondence. We show that these neurons respond in a temporally precise fashion to auditory presentation of certain note sequences in this songbird’s repertoire and to similar note sequences in other birds’ songs. These neurons display nearly identical patterns of activity when the bird sings the same sequence, and disrupting auditory feedback does not alter this singing-related activity, indicating it is motor in nature. Furthermore, these neurons innervate striatal structures important for song learning, raising the possibility that singing-related activity in these cells is compared to auditory feedback to guide vocal learning. |