Cognitive bias has become a popular way to access non-human animal mood, though inconsistent results have been found. In humans, mood and personality interact to determine cognitive bias, but to date, this has not been investigated in non-human animals. Here, we demonstrate for the first time, to the best of our knowledge, in a non-human animal, the domestic pig (Sus scrofa domesticus), that mood and personality interact, impacting on judgement. Pigs with a more proactive personality were more likely to respond optimistically to unrewarded ambiguous probes (spatially positioned between locations that were previously rewarded and unrewarded) independent of their housing (or enrichment) conditions. However, optimism/pessimism of reactive pigs in this task was affected by their housing conditions, which are likely to have influenced their mood state. Reactive pigs in the less enriched environment were more pessimistic and those in the more enriched environment, more optimistic. These results suggest that judgement in non-human animals is similar to humans, incorporating aspects of stable personality traits and more transient mood states.

Correct assessment of stress in horses is important for both horse welfare and handler safety during necessary aversive procedures. Handlers depend on behaviour when judging how well an individual is tolerating stressful procedures such as loading or veterinary intervention. However, evidence suggests that behaviour may not accurately reflect affective states in horses. This may be explained by individual

Emotions are mental states occurring in response to external and internal stimuli and thus form an integral part of an animal’s behaviour. Emotions can be mapped in two dimensions based on their arousal and valence. Whilst good indicators of arousal exist, clear indicators of emotional valence, particularly positive valence, are still rare. However, positively valenced emotions may play a crucial role in social interactions in many species and thus, an understanding of how emotional valence is expressed is needed. Vocalisations are a potential indicator of emotional valence as they can reflect the internal state of the caller. We experimentally manipulated valence, using positive and negative cognitive bias trials, to quantify changes in pig vocalisations. We found that grunts were shorter in positive trials than in negative trials. Interestingly, we did not find differences in the other measured acoustic parameters between the positive and negative contexts as reported in previous studies. These differences in results suggest that acoustic parameters may differ in their sensitivity as indicators of emotial valence. However, it is important to understand how similar contexts are, in terms of their valence, to be able to fully understand how and when acoustic parameters reflect emotional states.

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Human-animal bond is receiving increasing attention and is thought to confer benefits on wellbeing and performance in working animals. One important benefit of bonding is the "safe base" an attachment figure provides, which manifests in better coping and increased exploration during potential threat. However, there is limited research exploring the existence or benefits of human-horse bonds, though bonding is sought after by both pleasure and elite riders. The purpose of the current study was to determine whether the presence of horses' owners confers a safe-base, therefore improving horse behaviour and physiological stress responses during novel handling tests. Horses completed two different handling tests, one with their owner and the other with an unfamiliar experimental handler (n = 46). Test and handler order was randomised and handlers were double blind to the performance of the horse with the alternate handler. Time taken to complete the tests and proactive behaviour were measured as indicators of performance and compliance. Core temperature, discrepancy in eye temperature, heart rate and heart rate variability were recorded to assess stress responses. If horses experience a "safe base" effect in the vicinity of their owner, they would be expected to show lower stress responses and greater behavioural compliance, compared to being handled by a stranger. There was no difference in behaviour or any physiological stress response between the handlers. This indicates that a calm, competent, but unknown handler may be equally effective to an owner during stressful procedures as neither equine performance nor affective state supported a safe-base effect. This supports previous research suggesting that the level of bond between human and horse may not be the most salient factor in coping or compliance during training and handling. These findings have implications for veterinary and clinical behaviour counselling, where novel human handlers must modify behaviour under potentially stressful circumstances.