Abstract: Olfaction is a major sensory element in intraspecies recognition and communication in mice. The present study investigated scent marking behaviors of males of the highly inbred C57BL/6J (C57) strain in order to evaluate the ability of these behaviors to provide clear and consistent measures of social familiarity and response to social signals. C57 males engage in scent marking when placed in a chamber with a wire mesh partition separating them from a conspecific. Male mice (C57 or outbred CD-1 mice) showed rapid habituation of scent marking (decreased marking over trials) with repeated exposure at 24-h intervals, to a stimulus animal of the C57 or CD-1 strains, or to an empty chamber. Subsequent exposure to a genetically different novel mouse (CD-1 after CD-1 exposure, or CD-1 after C57 exposure) or to a novel context (different shaped chamber) produced recovery of marking, while responses to a novel but genetically identical mouse (C57 after C57 exposure) or to the empty chamber did not. This finding demonstrated that male mice differentiate familiar and novel conspecifics as expressed by habituation and recovery of scent marking, but neither C57 or CD-1 mice can differentiate new vs. familiar C57 males; likely due to similarities in their odor patterns. The data also indicate that scent marking can differentiate novel from familiar contexts.

Abstract: Lateralization of emotions has received great attention in the last decades, both in humans and animals, but little interest has been given to side bias in perceptual processing. Here, we investigated the influence of the emotional valence of stimuli on visual and olfactory explorations by horses, a large mammalian species with two large monocular visual fields and almost complete decussation of optic fibres. We confronted 38 Arab mares to three objects with either a positive, negative or neutral emotional valence (novel object). The results revealed a gradient of exploration of the 3 objects according to their emotional value and a clear asymmetry in visual exploration. When exploring the novel object, mares used preferentially their right eyes, while they showed a slight tendency to use their left eyes for the negative object. No asymmetry was evidenced for the object with the positive valence. A trend for an asymmetry in olfactory investigation was also observed. Our data confirm the role of the left hemisphere in assessing novelty in horses like in many vertebrate species and the possible role of the right hemisphere in processing negative emotional responses. Our findings also suggest the importance of both hemispheres in the processing positive emotions. This study is, to our knowledge, the first to demonstrate clearly that the emotional valence of a stimulus induces a specific visual lateralization pattern.

Abstract: It has been suggested that social dynamics affect social learning but empirical support for this idea is scarce. Here we show that affiliate relationships among kin indeed enhance the performance of common ravens, Corvus corax, in a social learning task. Via daily behavioural protocols we first monitored social dynamics in our group of captive young ravens. Siblings spent significantly more time in close proximity to each other than did nonsiblings. We subsequently tested birds on a stimulus enhancement task in model-observer dyads composed of both siblings and nonsiblings. During demonstration the observer could watch the model manipulating one particular object (target object) in an adjacent room. After removing the model, the observer was confronted with five different objects including the former target object. Observers from sibling dyads handled the target object for significantly longer periods of time as compared with the other four available objects, whereas observers from nonsibling dyads did not show a preference for the target object. Also, siblings matched the model's decision to cache or not to cache objects significantly more often than did nonsiblings. Hence, siblings were likely to attend to both, the behaviour of the model (caching or noncaching) and object-specific details. Our results support the hypothesis that affiliate relations between individuals affect the transmission of information and may lead to directed social learning even when spatial proximity has been experimentally controlled for.

Abstract: Individual recognition is considered a complex process and, although it is believed to be widespread across animal taxa, the cognitive mechanisms underlying this ability are poorly understood. An essential feature of individual recognition in humans is that it is cross-modal, allowing the matching of current sensory cues to identity with stored information about that specific individual from other modalities. Here, we use a cross-modal expectancy violation paradigm to provide a clear and systematic demonstration of cross-modal individual recognition in a nonhuman animal: the domestic horse. Subjects watched a herd member being led past them before the individual went of view, and a call from that or a different associate was played from a loudspeaker positioned close to the point of disappearance. When horses were shown one associate and then the call of a different associate was played, they responded more quickly and looked significantly longer in the direction of the call than when the call matched the herd member just seen, an indication that the incongruent combination violated their expectations. Thus, horses appear to possess a cross-modal representation of known individuals containing unique auditory and visual/olfactory information. Our paradigm could provide a powerful way to study individual recognition across a wide range of species.

Abstract: The long-held belief that human dominance and equine submission are key to successful training and that the horse must be taught to [`]respect' the trainer infers that force is often used during training. Many horses respond by trialling unwelcome evasions, resistances and flight responses, which readily become established. When unable to cope with problem behaviours, some handlers in the past might have been encouraged to use harsh methods or devices while others may have called in a so-called [`]good horseman' or [`]horse whisperer' to remediate the horse. Frequently, the approaches such practitioners offer could not be applied by the horse's owner or trainer because of their lack of understanding or inability to apply the techniques. Often it seemed that these [`]horse-people' had magical ways with horses (e.g., they only had to whisper to them) that achieved impressive results although they had little motivation to divulge their techniques. As we begin to appreciate how to communicate with horses sensitively and consistently, misunderstandings and misinterpretations by horse and trainer should become less common. Recent studies have begun to reveal what comprises the simplest, most humane and most effective mechanisms in horse training and these advances are being matched by greater sharing of knowledge among practitioners. Indeed, various practitioners of what is referred to here as [`]natural horsemanship' now use techniques similar to the [`]whisperers' of old, but they are more open about their methods. Reputable horse trainers using natural horsemanship approaches are talented observers of horse behaviour and respond consistently and swiftly to the horse's subtle cues during training. For example, in the roundpen these trainers apply an aversive stimulus to prompt a flight response and then, when the horse slows down, moves toward them, or offers space-reducing affiliative signals, the trainer immediately modifies his/her agonistic signals, thus negatively reinforcing the desired response. Learning theory and equine ethology, the fundamentals of the emerging discipline of equitation science, can be used to explain almost all the behaviour modification that goes on in these contexts and in conventional horsemanship. By measuring and evaluating what works and what does not, equitation science has the potential to have a unifying effect on traditional practices and developing branches of equitation.