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Lusseau, D.; Whitehead, H.; Gero, S. |
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Title |
Incorporating uncertainty into the study of animal social networks |
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Journal Article |
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Year |
2008 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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75 |
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5 |
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1809-1815 |
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bootstrap; social behaviour; social network; social structure |
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0003-3472 |
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Equine Behaviour @ team @ |
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5173 |
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Author |
King, A.J.; Douglas, C.M.S.; Huchard, E.; Isaac, N.J.B.; Cowlishaw, G. |
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Title |
Dominance and affiliation mediate despotism in a social primate |
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Journal Article |
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Year |
2008 |
Publication |
Current Biology : CB |
Abbreviated Journal |
Curr Biol |
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Volume |
18 |
Issue |
23 |
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1833-1838 |
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Animals; *Authoritarianism; Behavior, Animal/*physiology; Cooperative Behavior; *Decision Making; Feeding Behavior; Female; *Group Processes; Male; Papio ursinus/*psychology; *Social Dominance |
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Group-living animals routinely have to reach a consensus decision and choose between mutually exclusive actions in order to coordinate their activities and benefit from sociality. Theoretical models predict “democratic” rather than “despotic” decisions to be widespread in social vertebrates, because they result in lower “consensus costs”-the costs of an individual foregoing its optimal action to comply with the decision-for the group as a whole. Yet, quantification of consensus costs is entirely lacking, and empirical observations provide strong support for the occurrence of both democratic and despotic decisions in nature. We conducted a foraging experiment on a wild social primate (chacma baboons, Papio ursinus) in order to gain new insights into despotic group decision making. The results show that group foraging decisions were consistently led by the individual who acquired the greatest benefits from those decisions, namely the dominant male. Subordinate group members followed the leader despite considerable consensus costs. Follower behavior was mediated by social ties to the leader, and where these ties were weaker, group fission was more likely to occur. Our findings highlight the importance of leader incentives and social relationships in group decision-making processes and the emergence of despotism. |
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Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK. andrew.king@ioz.ac.uk |
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English |
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0960-9822 |
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PMID:19026539 |
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Equine Behaviour @ team @ |
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5124 |
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Li, W.; Howard, J.D.; Parrish, T.B.; Gottfried, J.A. |
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Title |
Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues |
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Journal Article |
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Year |
2008 |
Publication |
Science |
Abbreviated Journal |
Science |
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Volume |
319 |
Issue |
5871 |
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1842-1845 |
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Learning to associate sensory cues with threats is critical for minimizing aversive experience. The ecological benefit of associative learning relies on accurate perception of predictive cues, but how aversive learning enhances perceptual acuity of sensory signals, particularly in humans, is unclear. We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior. |
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10.1126/science.1152837 |
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Equine Behaviour @ team @ |
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4408 |
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Li, W.; Howard, J.D.; Parrish, T.B.; Gottfried, J.A. |
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Supporting Online Material to: Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues |
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Miscellaneous |
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Year |
2008 |
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Science |
Abbreviated Journal |
Science |
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319 |
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5871 |
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1842-1845 |
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Learning to associate sensory cues with threats is critical for minimizing aversive experience. The ecological benefit of associative learning relies on accurate perception of predictive cues, but how aversive learning enhances perceptual acuity of sensory signals, particularly in humans, is unclear. We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior. |
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10.1126/science.1152837 |
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Equine Behaviour @ team @ |
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4409 |
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Stueckle, S.; Zinner, D. |
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Title |
To follow or not to follow: decision making and leadership during the morning departure in chacma baboons |
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Journal Article |
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Year |
2008 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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Volume |
75 |
Issue |
6 |
Pages |
1995-2004 |
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Keywords |
chacma baboon; collective movement; consensus; decision making; leadership; Papio hamadryas ursinus |
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To benefit from group living, group members need to keep the group cohesive by coordinating time and direction of travelling. Self-organization and leadership are two means of coordination and two types of decision can be made on the group level: combined and consensus. We studied the initiation process of group movements during the morning departure of a group of chacma baboons, Papio hamadryas ursinus, from its sleeping site in De Hoop Nature Reserve, South Africa. Findings from other female-bonded primate groups led us to hypothesize that females should play a major role in the decision-making process. Approximately 75% of the adults made a start attempt, with 62 of 92 attempts being by males. There was no sex difference in the probability of being successful when initiating an attempt. Lactating females initiated fewer than pregnant or cycling females. Thus, at least for this group of chacma baboons, leadership appeared to be distributed and the decision about the timing of departure and travel direction seemed to be a partially shared consensus decision with adult males contributing more to the decision outcome, with a slightly more prominent role of the dominant male. Our results do not support the [`]leading females' hypothesis. No behavioural patterns that might serve as specialized signals leading to a more successful recruitment of other group members were observed. The departure process appeared to be coordinated merely through individuals setting an example by moving off. |
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0003-3472 |
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Equine Behaviour @ team @ |
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5130 |
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Hemelrijk, C. K.; Wantia, J,; Isler, K. |
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Title |
Female Dominance over Males in Primates: Self-Organisation and Sexual Dimorphism |
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Journal Article |
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Year |
2008 |
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PLoS ONE |
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PLoS ONE |
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3 |
Issue |
7 |
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e2678 |
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The processes that underlie the formation of the dominance hierarchy in a group are since long under debate. Models of self-organisation suggest that dominance hierarchies develop by the self-reinforcing effects of winning and losing fights (the so-called winner-loser effect), but according to ‘the prior attribute hypothesis’, dominance hierarchies develop from pre-existing individual differences, such as in body mass. In the present paper, we investigate the relevance of each of these two theories for the degree of female dominance over males. We investigate this in a correlative study in which we compare female dominance between groups of 22 species throughout the primate order. In our study female dominance may range from 0 (no female dominance) to 1 (complete female dominance). As regards ‘the prior attribute hypothesis’, we expected a negative correlation between female dominance over males and species-specific sexual dimorphism in body mass. However, to our surprise we found none (we use the method of independent contrasts). Instead, we confirm the self-organisation hypothesis: our model based on the winner-loser effect predicts that female dominance over males increases with the percentage of males in the group. We confirm this pattern at several levels in empirical data (among groups of a single species and between species of the same genus and of different ones). Since the winner-loser effect has been shown to work in many taxa including humans, these results may have broad implications.3 |
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Equine Behaviour @ team @ |
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5115 |
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Webster, M.M.; Laland, K.N. |
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Title |
Social learning strategies and predation risk: minnows copy only when using private information would be costly |
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Journal Article |
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Year |
2008 |
Publication |
Proc Biol Sci |
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Proc. R. Soc. Lond. B |
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275 |
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1653 |
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2869-2876 |
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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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Equine Behaviour @ team @ |
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6196 |
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Dwan, K.; Altman, D.G.; Arnaiz, J.A.; Bloom, J.; Chan, A.-W.; Cronin, E.; Decullier, E.; Easterbrook, P.J.; Von Elm, E.; Gamble, C.; Ghersi, D.; Ioannidis, J.P.A.; Simes, J.; Williamson, P.R. |
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Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias |
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Journal Article |
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2008 |
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Plos One |
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Plos One |
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3 |
Issue |
8 |
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e3081 |
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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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Public Library of Science |
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Equine Behaviour @ team @ |
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6644 |
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Siniscalchi, M.; Quaranta, A.; Rogers, L.J. |
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Hemispheric specialization in dogs for processing different acoustic stimuli |
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2008 |
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PloS ONE |
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3 |
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e3349 |
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Equine Behaviour @ team @ |
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5415 |
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Roth, L.S.V.; Balkenius, A.; Kelber, A. |
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Title |
The Absolute Threshold of Colour Vision in the Horse |
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2008 |
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PLoS ONE |
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PLoS ONE |
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3 |
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11 |
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e3711 EP - |
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<p>Arrhythmic mammals are active both during day and night if they are allowed. The arrhythmic horses are in possession of one of the largest terrestrial animal eyes and the purpose of this study is to reveal whether their eye is sensitive enough to see colours at night. During the day horses are known to have dichromatic colour vision. To disclose whether they can discriminate colours in dim light a behavioural dual choice experiment was performed. We started the training and testing at daylight intensities and the horses continued to choose correctly at a high frequency down to light intensities corresponding to moonlight. One Shetland pony mare, was able to discriminate colours at 0.08 cd/m2, while a half blood gelding, still discriminated colours at 0.02 cd/m2. For comparison, the colour vision limit for several human subjects tested in the very same experiment was also 0.02 cd/m2. Hence, the threshold of colour vision for the horse that performed best was similar to that of the humans. The behavioural results are in line with calculations of the sensitivity of cone vision where the horse eye and human eye again are similar. The advantage of the large eye of the horse lies not in colour vision at night, but probably instead in achromatic tasks where presumably signal summation enhances sensitivity.</p> |
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Equine Behaviour @ team @ |
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5625 |
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