Noy, L., Dekel, E., & Alon, U. (2011). The mirror game as a paradigm for studying the dynamics of two people improvising motion together. Proceedings of the National Academy of Sciences, .
Abstract: Joint improvisation is the creative action of two or more people without a script or designated leader. Examples include improvisational theater and music, and day-to-day activities such as conversations. In joint improvisation, novel action is created, emerging from the interaction between people. Although central to creative processes and social interaction, joint improvisation remains largely unexplored due to the lack of experimental paradigms. Here we introduce a paradigm based on a theater practice called the mirror game. We measured the hand motions of two people mirroring each other at high temporal and spatial resolution. We focused on expert actors and musicians skilled in joint improvisation. We found that players can jointly create novel complex motion without a designated leader, synchronized to less than 40 ms. In contrast, we found that designating one player as leader deteriorated performance: The follower showed 2–3 Hz oscillation around the leader's smooth trajectory, decreasing synchrony and reducing the range of velocities reached. A mathematical model suggests a mechanism for these observations based on mutual agreement on future motion in mirrored reactive–predictive controllers. This is a step toward understanding the human ability to create novelty by improvising together.
|
Romero L. M. (2011). Using the reactive scope model to understand why stress physiology predicts survival during starvation in Galápagos marine iguanas. Gen Comp Endocrinol, .
Abstract: Even though the term “stress” is widely used, a precise definition is notoriously difficult. Notwithstanding this difficulty, stress continues to be an important concept in biology because it attempts to describe how animals cope with environmental change under emergency conditions. Without a precise definition, however, it becomes nearly impossible to make testable a priori predictions about how physiological and hormonal systems will respond to emergency conditions and what the ultimate impact on the animal will be. The reactive scope model is a recent attempt to formulate testable predictions. This model provides a physiological basis to explain why corticosterone negative feedback, but not baseline corticosterone concentrations, corticosterone responses to acute stress, or the interrenal capacity to secrete corticosterone, is correlated with survival during famine conditions in Galápagos marine iguanas. Reactive scope thus provides a foundation for interpreting and predicting physiological stress responses.
|
Hobaiter, C., & Byrne, R. (2011). The gestural repertoire of the wild chimpanzee. Anim. Cogn., 14(5), 745–767.
Abstract: Great ape gestural communication is known to be intentional, elaborate and flexible; yet there is controversy over the best interpretation of the system and how gestures are acquired, perhaps because most studies have been made in restricted, captive settings. Here, we report the first systematic analysis of gesture in a population of wild chimpanzees. Over 266 days of observation, we recorded 4,397 cases of intentional gesture use in the Sonso community, Budongo, Uganda. We describe 66 distinct gesture types: this estimate appears close to asymptote, and the Sonso repertoire includes most gestures described informally at other sites. Differences in repertoire were noted between individuals and age classes, but in both cases, the measured repertoire size was predicted by the time subjects were observed gesturing. No idiosyncratic usages were found, i.e. no gesture type was used only by one individual. No support was found for the idea that gestures are acquired by ‘ontogenetic ritualization’ from originally effective actions; moreover, in detailed analyses of two gestures, action elements composing the gestures did not closely match those of the presumed original actions. Rather, chimpanzee gestures are species-typical; indeed, many are ‘family-typical’, because gesture types recorded in gorillas, orangutans and chimpanzee overlap extensively, with 24 gestures recorded in all three genera. Nevertheless, chimpanzee gestures are used flexibly across a range of contexts and show clear adjustment to audience (e.g. silent gestures for attentive targets, contact gestures for inattentive ones). Such highly intentional use of a species-typical repertoire raises intriguing questions for the evolution of advanced communication.
|
Melis, A. P., Warneken, F., Jensen, K., Schneider, A. - C., Call, J., & Tomasello, M. (2011). Chimpanzees help conspecifics obtain food and non-food items. Proceedings of the Royal Society B: Biological Sciences, 278(1710), 1405–1413.
Abstract: Chimpanzees (Pan troglodytes) sometimes help both humans and conspecifics in experimental situations in which immediate selfish benefits can be ruled out. However, in several experiments, chimpanzees have not provided food to a conspecific even when it would cost them nothing, leading to the hypothesis that prosociality in the food-provisioning context is a derived trait in humans. Here, we show that chimpanzees help conspecifics obtain both food and non-food items—given that the donor cannot get the food herself. Furthermore, we show that the key factor eliciting chimpanzees' targeted helping is the recipients' attempts to either get the food or get the attention of the potential donor. The current findings add to the accumulating body of evidence that humans and chimpanzees share the motivation and skills necessary to help others in situations in which they cannot selfishly benefit. Humans, however, show prosocial motives more readily and in a wider range of contexts.
|
König von Borstel, U., Euent, S., Graf, P., König, S., & Gauly, M. (2011). Equine behaviour and heart rate in temperament tests with or without rider or handler. Physiol. Behav., 104(3), 454–463.
Abstract: The aim of the present study was to compare horses' heart rate (HR), heart rate variability (RMSSD, pNN50) and behaviour in the same temperament test when being ridden, led, and released free. Behavioural measurements included scores and linear measurements for reactivity (R), activity (A), time to calm down (T) and emotionality (E), recorded during the approach (1) and/or during confrontation with the stimulus (2). Sixty-five horses were each confronted 3 times (1 ridden, 1 led, 1 free running in balanced order) with 3 novel and/or sudden stimuli. Mixed model analysis indicated that leading resulted in the lowest (P < 0.05 throughout) reactions as measured by A1, A2, E1, E2, R2, and pNN50 while riding produced the strongest (A1, T2, HR, RMSSD, pNN50) or medium (E1, E2, R2) reactions. Free running resulted either in the strongest (A2, E1, E2, R2) or in the lowest (A1, T2, HR, RMSSD, pNN50) reactions. The repeatability across tests for HR (0.57), but not for RMSSD (0.23) or pNN50 (0.25) was higher than for any behavioural measurement: the latter ranged from values below 0.10 (A1, A2, T2) to values between 0.30 and 0.45 (E1, E2, R2). Overall, the results show that a rider or handler influences, but not completely masks, the horses' intrinsic behaviour in a temperament test, and this influence appeared to be stronger on behavioural variables and heart rate variability than on the horses' heart rates. Taking both practical considerations and repeatabilities into account, reactivity appears to be the most valuable parameter. Emotionality and heart rate can also yield valid results reflecting additional dimensions of temperament although their practical relevance may be less obvious. If a combination of observed variables is chosen with care, a valid assessment of a horse's temperament may be possible in all types of tests. However, in practice, tests that resemble the practical circumstances most closely, i.e. testing riding horses under a rider, should be chosen.
|
McComb, K., Shannon, G., Durant, S. M., Sayialel, K., Slotow, R., Poole, J., et al. (2011). Leadership in elephants: the adaptive value of age. Proc. R. Soc. Lond. B., 278(1722), 3270–3276.
Abstract: The value of age is well recognized in human societies, where older individuals often emerge as leaders in tasks requiring specialized knowledge, but what part do such individuals play in other social species? Despite growing interest in how effective leadership might be achieved in animal social systems, the specific role that older leaders may play in decision-making has rarely been experimentally investigated. Here, we use a novel playback paradigm to demonstrate that in African elephants (Loxodonta africana), age affects the ability of matriarchs to make ecologically relevant decisions in a domain critical to survival—the assessment of predatory threat. While groups consistently adjust their defensive behaviour to the greater threat of three roaring lions versus one, families with younger matriarchs typically under-react to roars from male lions despite the severe danger they represent. Sensitivity to this key threat increases with matriarch age and is greatest for the oldest matriarchs, who are likely to have accumulated the most experience. Our study provides the first empirical evidence that individuals within a social group may derive significant benefits from the influence of an older leader because of their enhanced ability to make crucial decisions about predatory threat, generating important insights into selection for longevity in cognitively advanced social mammals.
|
Gesquiere, L. R., Learn, N. H., Simao, M. C. M., Onyango, P. O., Alberts, S. C., & Altmann, J. (2011). Life at the Top: Rank and Stress in Wild Male Baboons. Science, 333(6040), 357–360.
Abstract: In social hierarchies, dominant individuals experience reproductive and health benefits, but the costs of social dominance remain a topic of debate. Prevailing hypotheses predict that higher-ranking males experience higher testosterone and glucocorticoid (stress hormone) levels than lower-ranking males when hierarchies are unstable but not otherwise. In this long-term study of rank-related stress in a natural population of savannah baboons (Papio cynocephalus), high-ranking males had higher testosterone and lower glucocorticoid levels than other males, regardless of hierarchy stability. The singular exception was for the highest-ranking (alpha) males, who exhibited both high testosterone and high glucocorticoid levels. In particular, alpha males exhibited much higher stress hormone levels than second-ranking (beta) males, suggesting that being at the very top may be more costly than previously thought.
|
|
Steidele, N. (2011). Beobachtungen einer Przewalski-Junggesellenherde im Jahresverlauf unter besonderer Berücksichtigung von Ruheverhalten und Rangordnung.
|
|
Neumann, C., Duboscq, J., Dubuc, C., Ginting, A., Irwan, A. M., Agil, M., et al. (2011). Assessing dominance hierarchies: validation and advantages of progressive evaluation with Elo-rating. Animal Behaviour, 82(4), 911–921.
|
Baragli, P., Vitale, V., Paoletti, E., Sighieri, C., & Reddon, A. R. (2011). Detour behaviour in horses (Equus caballus). J. Ethol., 29(2), 227–234.
Abstract: The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks subjects were required to perform a detour around an asymmetrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was consistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities.
|
