| Records |
| Author |
Jørgensen, G.H.M.; Liestøl, S.H.-O.; Bøe, K.E. |
| Title |
Effects of enrichment items on activity and social interactions in domestic horses (Equus caballus) |
Type |
Journal Article |
| Year |
2011 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
| Volume |
129 |
Issue |
2-4 |
Pages |
100-110 |
| Keywords |
Horse; Activity; Behaviour; Item; Enrichment; Social interactions |
| Abstract |
The aim of this study was to investigate the use of items intended to provide enrichment during turnout, both for individual and group kept horses in an attempt to reduce the amount of passive behaviours. The study was divided into two parts, where study 1 involved eight horses rotated through eight individual paddocks, each containing one of seven enrichment items and one paddock being kept without item, functioning as a control. The horses' item-directed behaviours; passive behaviours or other non-item related activities were scored using instantaneous sampling, every minute for 1 h at the beginning and the end of the turnout period. Study 2 involved six horse groups (3-6 horses) and the same scoring methods and ethogram as in study 1. The four items that the horses interacted the most with during study 1 (straw STRA, ball filled with concentrates CBALL, branches BRAN and scratching pole POLE) are investigated in study 2. In addition, the amount of social interactions was recorded. Both horses kept individually (P < 0.05) and in groups (P < 0.0001) performed significantly more item-directed behaviours towards edible items like STRA and CBALL than other objects. There was, however, no overall relation between the numbers of item-directed behaviours and the number of passive behaviours observed, indicating that the enrichment items did not alone reduce the amount of passive behaviours during turnout periods. Such a reduction was, however, only apparent when horses spent more time eating green leaves growing on the paddock surface (R = -0.97 study 1, R = -0.67 study 2, P < 0.0001). Access to STRA in group kept horses also seemed to reduce the amount of agonistic behaviours (P < 0.0001). In conclusion, if grass is not available in paddocks, the provision of roughage reduces the amount of passive behaviours in singly kept horses and it also reduces the risk of agonistic interactions between horses kept in group. |
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0168-1591 |
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Equine Behaviour @ team @ |
Serial |
5320 |
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| Author |
Parker, G.A.; Rubenstein, D.I. |
| Title |
Role assessment, reserve strategy, and acquisition of information in asymmetric animal conflicts |
Type |
Journal Article |
| Year |
1981 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
29 |
Issue |
1 |
Pages |
221-240 |
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| Abstract |
It was formerly argued that alternative evolutionarily stable strategies (ESSs) are possible for animal contests characterized by some asymmetry that can be perceived with perfect accuracy. Where roles A and B refer to the asymmetry between opponents, ESSs are: [`]fight when A, retreat when B', and vice versa. Either can be an ESS, but only if the [`]reserve strategy' (=what an animal does when it fights) is sufficiently damaging. We examine the [`]war of attrition' (winner = opponent that persists longer). In a population at either ESS, reserve strategy is never normally shown; it is therefore subject to drift unless the selective action of rare individuals which break the convention is considered. These could arise either by mutation or by mistakes in role assessment. When mutations and mistakes simply specify that occasionally an animal fights when it [`]should' retreat, selection adjusts reserve strategy to a level where only one ESS (the [`]commonsense' ESS) is possible, if the asymmetry is relevant to payoff. Thus for asymmetries in fighting ability or resource value, the individual with the lower score will retreat. However, we are particularly concerned with cases where both payoff-relevant aspects (fighting ability and resource value) are asymmetric. If opponents sustain contest costs at rates KA and KB, and their resource values are VA and VB, an [`]optimal assessor' strategy defined by the interaction between the two asymmetries, is a unique ESS. It obeys the rule [`]fight on estimating role A, where VA/KA>VB/KB; retreat in B'. If mistakes can occur in both roles, but are very rate, the ESS is not fundamentally altered though there will be infinitesimal tendencies for persisting in role B. Selection to improve assessment abilities intensifies as abilities improve, but is weak if roles A and B are rather similar. Over a range of similarity between roles, an [`]owner wins' convention may be adopted if ownership correlates positively with role A and an individual cannot tell when it would otherwise pay him to break the convention. We also examine a contest in which information about roles can be acquired only during a contest itself, and at a cost. Much depends on the rate at which information is acquired relative to the rate at which costs are expended, and on whether contests normally escalate in intensity, remain at the same level, or de-escalate. Selection favours short contests when costs are high relative to resource value, where the outcome of a round contains much information about fighting ability, and where the actual disparity in fighting ability is large. |
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0003-3472 |
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Equine Behaviour @ team @ |
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5325 |
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| Author |
Vallortigara, G.; Andrew, R.J. |
| Title |
Differential involvement of right and left hemisphere in individual recognition in the domestic chick |
Type |
Journal Article |
| Year |
1994 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
| Volume |
33 |
Issue |
1-2 |
Pages |
41-57 |
| Keywords |
Right hemisphere; Left hemisphere; Domestic fowl; Lateralization; Chick |
| Abstract |
Right hemisphere advantage in individual recognition (as shown by differences between response to strangers and companions) is clear in the domestic chick. Chicks using the left eye (and so, thanks to the complete optic decussation, predominantly the right hemisphere) discriminate between stranger and companion. Chicks using the right eye discriminate less clearly or not at all. The ability of left eyed chicks to respond to differences between strangers and companions stimuli is associated with a more general ability to detect and respond to novelty: this difference between left and right eyed chicks also holds for stimuli which are not social partners. The right hemisphere also shows advantage in tasks with a spatial component (topographical learning; response to change in the spatial context of a stimulus) in the chick, as in humans. Similar specialisations of the two hemispheres are also revealed in tests which involve olfactory cues presented by social partners. The special properties of the left hemisphere are less well established in the chick. Evidence reviewed here suggests that it tends to respond to selected properties of a stimulus and to use them to assign it to a category; such assignment then allows an appropriate response. When exposed to an imprinting stimulus (visual or auditory) a chick begins by using right eye or ear (suggesting left hemisphere control), and then shifts to the left eye or ear (suggesting right hemisphere control), as exposure continues. The left hemisphere here is thus involved whilst behaviour is dominated by vigorous response to releasing stimuli presented by an object. Subsequent learning about the full detailed properties of the stimulus, which is crucial for individual recognition, may explain the shift to right hemisphere control after prolonged exposure to the social stimulus. There is a marked sex difference in choice tests: females tend to choose companions in tests where males choose strangers. It is possible that this difference is specifically caused by stronger motivation to sustain social contact in female chicks, for which there is extensive evidence. However, sex differences in response to change in familiar stimuli are also marked in tests which do not involve social partners. Finally, in both sexes there are two periods during development in which there age-dependent shifts in bias to use one or other hemisphere. These periods (days 3-5 and 8-11) coincide with two major changes in the social behaviour of chicks reared by a hen in a normal brood. It is argued that one function of these periods is to bring fully into play the hemisphere most appropriate to the type of response to, and learning about, social partners which is needed at particular points in development. Parallels are discussed between the involvement of lateralised processes in the recognition of social partners in chicks and humans. |
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0376-6357 |
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no |
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Equine Behaviour @ team @ |
Serial |
5341 |
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Harris, L.J.; Almerigi, J.B.; Carbary, T.J.; Fogel, T.G. |
| Title |
Left-side infant holding: A test of the hemispheric arousal -attentional hypothesis |
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Journal Article |
| Year |
2001 |
Publication |
Brain and Cognition |
Abbreviated Journal |
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| Volume |
46 |
Issue |
1-2 |
Pages |
159-165 |
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| Abstract |
When asked to hold a young infant in their arms, most adults hold on the left side (Harris, 1997). In a prior study, we found the same bias when we asked adults merely to imagine holding an infant in their arms (Harris, Almerigi, & Kirsch, 1999). It has been hypothesized that the left-side bias is the product of right-hemisphere arousal accompanying certain aspects of the act, causing attention to be driven to the contralateral, or left, side of personal space. Left-side holding, whether actual or imagined, thus would be consistent with the direction to which the holder's attention has been endogenously directed. We tested this hypothesis by giving 250 college students the “imagine-holding” task and then, as an independent measure of lateralized hemispheric arousal, a 34-item Chimeric Faces Test (CFT). On the “imagine” test, a significant majority reported a left-side hold, and, on the CFT, left-side holders had a significantly stronger left-hemispace bias than right-side holders, although both left- and right- side holders had left-hemispace CFT biases. The results thus support the attentional-arousal hypothesis but indicate that other factors are contributing as well. |
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0278-2626 |
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Equine Behaviour @ team @ |
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5344 |
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| Author |
Ghirlanda, S.; Vallortigara, G. |
| Title |
The evolution of brain lateralization: a game-theoretical analysis of population structure |
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Journal Article |
| Year |
2004 |
Publication |
Proceedings of the Royal Society of London. Series B: Biological Sciences |
Abbreviated Journal |
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| Volume |
271 |
Issue |
1541 |
Pages |
853-857 |
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In recent years, it has become apparent that behavioural and brain lateralization at the population level is the rule rather than the exception among vertebrates. The study of these phenomena has so far been the province of neurology and neuropsychology. Here, we show how such research can be integrated with evolutionary biology to understand lateralization more fully. In particular, we address the fact that, within a species, left– and right–type individuals often occur in proportions different from one–half (e.g. hand use in humans). The traditional explanations offered for lateralization of brain function (that it may avoid unnecessary duplication of neural circuitry and reduce interference between functions) cannot account for this fact, because increased individual efficiency is unrelated to the alignment of lateralization at the population level. A further puzzle is that such an alignment may even be disadvantageous, as it makes individual behaviour more predictable to other organisms. Here, we show that alignment of the direction of behavioural asymmetries in a population can arise as an evolutionarily stable strategy when individual asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Brain and behavioural lateralization, as we know it in humans and other vertebrates, may have evolved under basically ‘social’ selection pressures. |
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Equine Behaviour @ team @ |
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5345 |
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| Author |
Ghirlanda, S.; Frasnelli, E.; Vallortigara, G. |
| Title |
Intraspecific competition and coordination in the evolution of lateralization |
Type |
Journal Article |
| Year |
2009 |
Publication |
Philosophical Transactions of the Royal Society B: Biological Sciences |
Abbreviated Journal |
Phil. Trans. Biol. Sci. |
| Volume |
364 |
Issue |
1519 |
Pages |
861-866 |
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| Abstract |
Recent studies have revealed a variety of left–right asymmetries among vertebrates and invertebrates. In many species, left- and right-lateralized individuals coexist, but in unequal numbers (‘population-level’ lateralization). It has been argued that brain lateralization increases individual efficiency (e.g. avoiding unnecessary duplication of neural circuitry and reducing interference between functions), thus counteracting the ecological disadvantages of lateral biases in behaviour (making individual behaviour more predictable to other organisms). However, individual efficiency does not require a definite proportion of left- and right-lateralized individuals. Thus, such arguments do not explain population-level lateralization. We have previously shown that, in the context of prey–predator interactions, population-level lateralization can arise as an evolutionarily stable strategy when individually asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Here, we extend our model showing that populations consisting of left- and right-lateralized individuals in unequal numbers can be evolutionarily stable, based solely on strategic factors arising from the balance between antagonistic (competitive) and synergistic (cooperative) interactions. |
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Equine Behaviour @ team @ |
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5346 |
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Perez-Cruz, C.; Simon, M.; Czéh, B.; Flügge, G.; Fuchs, E. |
| Title |
Hemispheric differences in basilar dendrites and spines of pyramidal neurons in the rat prelimbic cortex: activity- and stress-induced changes |
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Journal Article |
| Year |
2009 |
Publication |
European Journal of Neuroscience |
Abbreviated Journal |
Eur. J. Neurosci. |
| Volume |
29 |
Issue |
4 |
Pages |
738-747 |
| Keywords |
dendrite; diurnal rhythm; lateralization; prefrontal cortex; spine |
| Abstract |
Abstract Pyramidal neurons of the rat medial prefrontal cortex have been shown to react to chronic stress by retracting their apical dendrites and by spine loss. We extended these findings by focusing on the basilar dendritic tree of layer III pyramidal neurons in both hemispheres of the rat prelimbic cortex. Animals were subjected to daily restraint stress for 1 week (6 h/day), during either the resting or the activity period. The morphology of basilar dendrites and spines of Golgi–Cox-stained neurons in the left and right hemispheres was digitally reconstructed and analyzed. We observed the following: (i) there was an inherent hemispheric asymmetry in control rats during the resting period: the number of spines on proximal dendrites was higher in the left than in the right hemisphere; (ii) basal dendrites in controls displayed a diurnal variation: there was more dendritic material during the resting period than in the activity period; (iii) chronic stress reduced the length of basal dendrites in only the right prelimbic cortex; (iv) chronic stress reduced spine density on proximal basal dendrites; (v) restraint stress during the activity period had more pronounced effects on the physiological stress parameters than restraint stress during the resting period. Our results show dynamic hemisphere-dependent structural changes in pyramidal neurons of the rat prelimbic cortex that are tightly linked to periods of resting and activity. These morphological alterations reflect the capacity of the neurons to react to external stimuli and mirror presumptive changes in neuronal communication. |
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Blackwell Publishing Ltd |
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1460-9568 |
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no |
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Equine Behaviour @ team @ |
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5355 |
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Edgar, G.K.; Smith, A.T. |
| Title |
Hemifield differences in perceived spatial frequency |
Type |
Journal Article |
| Year |
1990 |
Publication |
Perception |
Abbreviated Journal |
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| Volume |
19 |
Issue |
6 |
Pages |
759-766 |
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| Abstract |
Measurements of the perceived spatial frequency of stationary sinewave gratings were made with the gratings presented at the same eccentricity in the left, right, upper, and lower visual hemifields. Ten subjects performed the task binocularly with spatial frequencies of 1, 2, and 4 cycles deg-1. Two of these subjects also performed the task monocularly at 2 cycles deg-1. In the majority of cases, the spatial frequency of stimuli presented in the left and lower visual hemifields was overestimated relative to stimuli presented in the right and upper visual hemifields. The results were similar for all spatial frequencies tested, and the direction of the asymmetry was the same whether viewing was with the left eye, right eye or binocular, suggesting that the differences in perceived spatial frequency are not retinal in origin. |
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Pion Ltd |
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Equine Behaviour @ team @ |
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5374 |
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Kerth, G. |
| Title |
Group decision-making in animal societies |
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Book Chapter |
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2010 |
Publication |
Animal Behaviour: Evolution and Mechanisms |
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Issue |
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Pages |
241-265 |
| Keywords |
Life Sciences |
| Abstract |
Individuals need to coordinate their activities to benefit from group living. Thus group decisions are essential for societies, especially if group members cooperate with each other. Models show that shared (democratic) decisions outperform unshared (despotic) decisions, even if individuals disagree about actions. This is surprising as in most other contexts, differences in individual preferences lead to sex-, age-, or kin-specific behaviour. Empirical studies testing the predictions of the theoretical models have only recently begun to emerge. This applies particularly to group decisions in fission-fusion societies, where individuals can avoid decisions that are not in their interest. After outlining the basic ideas and theoretical models on group decision-making I focus on the available empirical studies. Originally most of the relevant studies have been on social insects and fish but recently an increasing number of studies on mammals and birds have been published, including some that deal with wild long-lived animals living in complex societies. This includes societies where group members have different interests, as in most mammals, and which have been less studied compared to eusocial insects that normally have no conflict among their colony members about what to do. I investigate whether the same decision rules apply in societies with conflict and without conflict, and outline open questions that remain to be studied. The chapter concludes with a synthesis on what is known about group decision-making in animals and an outlook on what I think should be done to answer the open questions. |
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Springer Berlin Heidelberg |
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Kappeler, P. |
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978-3-642-02624-9 |
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Equine Behaviour @ team @ |
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5381 |
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Krishnan, A.; Gandour, J.T.; Ananthakrishnan, S.; Bidelman, G.M.; Smalt, C.J. |
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Functional ear (a)symmetry in brainstem neural activity relevant to encoding of voice pitch: A precursor for hemispheric specialization? |
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Journal Article |
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Brain and Language |
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In Press, Corrected Proof |
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Auditory; Human; Brainstem; Pitch; Language; Mandarin Chinese; Fundamental frequency-following response (FFR); Functional ear asymmetry; Experience-dependent plasticity; Subcortical |
| Abstract |
Pitch processing is lateralized to the right hemisphere; linguistic pitch is further mediated by left cortical areas. This experiment investigates whether ear asymmetries vary in brainstem representation of pitch depending on linguistic status. Brainstem frequency-following responses (FFRs) were elicited by monaural stimulation of the left and right ear of 15 native speakers of Mandarin Chinese using two synthetic speech stimuli that differ in linguistic status of tone. One represented a native lexical tone (Tone 2: T2); the other, T2', a nonnative variant in which the pitch contour was a mirror image of T2 with the same starting and ending frequencies. Two 40-ms portions of f0 contours were selected in order to compare two regions (R1, early; R2 late) differing in pitch acceleration rate and perceptual saliency. In R2, linguistic status effects revealed that T2 exhibited a larger degree of FFR rightward ear asymmetry as reflected in f0 amplitude relative to T2'. Relative to midline (ear asymmetry = 0), the only ear asymmetry reaching significance was that favoring left ear stimulation elicited by T2'. By left- and right-ear stimulation separately, FFRs elicited by T2 were larger than T2' in the right ear only. Within T2', FFRs elicited by the earlier region were larger than the later in both ears. Within T2, no significant differences in FFRS were observed between regions in either ear. Collectively, these findings support the idea that origins of cortical processing preferences for perceptually-salient portions of pitch are rooted in early, preattentive stages of processing in the brainstem. |
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0093-934x |
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Equine Behaviour @ team @ |
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5391 |
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