Abstract: The growing recognition of animals as individuals has broader implications for farm animal welfare research. Even under highly standardized on-farm conditions, farm animals show heterogeneous but individually consistent behavioural patterns towards various stimuli, based on how they appraise these stimuli. As a result, animal welfare is likely to be highly individual as well, and studying the proximate mechanisms underlying distinct individual behaviour patterns and appraisal will improve animal welfare research. We propose to extend the framework of affective styles to bridge the gap between existing research fields on animal personality and affective states. Affective styles refer to consistent individual differences in emotional reactivity and regulation and can be predicted by baseline cerebral lateralization. Likewise, animals with consistent left or right motor biases--a proxy measure of individual patterns in cerebral lateralization--have been shown to differ in their personality, emotional reactivity, motivational tendencies or coping styles. In this paper, we present the current knowledge of the links between laterality and stable individual traits in behaviour and affect in light of hypotheses on emotional lateralization. Within our suggested framework, we make recommendations on how to investigate affective styles in non-human animals and give practical examples. This approach has the potential to promote a science of affective styles in nonhuman animals and significantly advance research on animal welfare.

Abstract: There are numerous reports of novel learned behaviour patterns in animal populations, yet the factors influencing the invention and spread of these innovations remain poorly understood. Here we investigated to what extent the pattern of spread of innovations in captive groups of starlings, Sturnus vulgaris, could be predicted by knowledge of individual and social group variables, including association patterns, social rank orders, measures of neophobia and asocial learning performance. We presented small groups of starlings with a series of novel extractive foraging tasks and recorded the latency for each bird to contact and solve each task, as well as the orders of contacting and solving. We then explored which variables best predicted the observed diffusion patterns. Object neophobia and social rank measures characterized who was the first of the group to contact the novel foraging tasks, and the subsequent spread of contacting tasks was associated with latency to feed in a novel environment. Asocial learning performance, measured in isolation, predicted who was the first solver of the novel foraging tasks in each group. Association patterns did not predict the spread of solving. Contact latency and solving duration were negatively correlated, consistent with social learning underlying the spread of solving. Our findings indicate that we can improve our understanding of the diffusion dynamics of innovations in animal groups by investigating group-dependent and individual variables in combination. We introduce novel methods for exploring predictors of the origin and spread of behavioural innovations that could be widely applied.

Abstract: Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or plain gray images were briefly presented as negative, positive, and control primes, followed by a mosaic mask. Then nonsense target ideographs were presented, and the subjects evaluated their partiality toward the targets. When the stimuli were presented in the left, but not the right, visual fields, the negative primes reduced the subjects' liking for the targets, relative to the case of the positive or control primes. These results provided behavioral evidence supporting the hypothesis that the right hemisphere is dominant for unconscious negative emotional processing.

Abstract: Consensus decisions about the nature and timing of group activities allow animals to maintain group cohesiveness, but also entail costs because individuals often differ with respect to their optimal activity budgets. Two mechanisms whereby animals reach a consensus include ‘consistent leadership’, in which a single dominant individual makes the decision, and ‘variable leadership’ in which several group members contribute to the decision outcome. Sharing of consensus decisions is expected to reduce consensus costs to most group members. Both patterns are thought to emerge from the complexity of social relationships of group members. We investigated the distribution of leadership during group departures in two packs of free-ranging dogs, Canis lupus familiaris, and tested how its distribution between individuals was affected by dominance rank-related affiliative and agonistic relationships. Although leadership was not entirely concentrated on a single group member, both packs had a limited number of habitual leaders. In the largest pack, the pattern of leadership changed from ‘variable’ to nearly ‘consistent’ after its size had shrunk. Habitual leaders were usually old and high-ranking individuals. However, high-ranking dogs that received affiliative submissions in greeting ceremonies were more likely to lead than dominant dogs receiving submissions only in agonistic contexts. During resting times, habitual followers associated more closely with habitual leaders than with other followers. These results suggest that in social species collective movements may arise from the effort of subordinates to maintain close proximity with specific valuable social partners.