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Valenchon, M., Lévy, F., Moussu, C., & Lansade, L. (2017). Stress affects instrumental learning based on positive or negative reinforcement in interaction with personality in domestic horses. Plos One, 12(5), e0170783.
Abstract: The present study investigated how stress affects instrumental learning performance in horses (Equus caballus) depending on the type of reinforcement. Horses were assigned to four groups (N = 15 per group); each group received training with negative or positive reinforcement in the presence or absence of stressors unrelated to the learning task. The instrumental learning task consisted of the horse entering one of two compartments at the appearance of a visual signal given by the experimenter. In the absence of stressors unrelated to the task, learning performance did not differ between negative and positive reinforcements. The presence of stressors unrelated to the task (exposure to novel and sudden stimuli) impaired learning performance. Interestingly, this learning deficit was smaller when the negative reinforcement was used. The negative reinforcement, considered as a stressor related to the task, could have counterbalanced the impact of the extrinsic stressor by focusing attention toward the learning task. In addition, learning performance appears to differ between certain dimensions of personality depending on the presence of stressors and the type of reinforcement. These results suggest that when negative reinforcement is used (i.e. stressor related to the task), the most fearful horses may be the best performers in the absence of stressors but the worst performers when stressors are present. On the contrary, when positive reinforcement is used, the most fearful horses appear to be consistently the worst performers, with and without exposure to stressors unrelated to the learning task. This study is the first to demonstrate in ungulates that stress affects learning performance differentially according to the type of reinforcement and in interaction with personality. It provides fundamental and applied perspectives in the understanding of the relationships between personality and training abilities.
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Fureix, C., Jego, P., Henry, S., Lansade, L., & Hausberger, M. (2012). Towards an Ethological Animal Model of Depression? A Study on Horses. PLoS ONE, 7(6), e39280 EP -.
Abstract: <sec><title>Background</title><p>Recent reviews question current animal models of depression and emphasise the need for ethological models of mood disorders based on animals living under natural conditions. Domestic horses encounter chronic stress, including potential stress at work, which can induce behavioural disorders (<italic>e.g.</italic> “apathy”). Our pioneering study evaluated the potential of domestic horses in their usual environment to become an ethological model of depression by testing this models’ face validity (<italic>i.e.</italic> behavioural similarity with descriptions of human depressive states).</p></sec><sec><title>Methodology/Principal Findings</title><p>We observed the spontaneous behaviour of 59 working horses in their home environment, focusing on immobility bouts of apparent unresponsiveness when horses displayed an atypical posture (termed <italic>withdrawn</italic> hereafter), evaluated their responsiveness to their environment and their anxiety levels, and analysed cortisol levels. Twenty-four percent of the horses presented the withdrawn posture, also characterized by gaze, head and ears fixity, a profile that suggests a spontaneous expression of “behavioural despair”. When compared with control “non-withdrawn” horses from the same stable, withdrawn horses appeared more indifferent to environmental stimuli in their home environment but reacted more emotionally in more challenging situations. They exhibited lower plasma cortisol levels. Withdrawn horses all belonged to the same breed and females were over-represented.</p></sec><sec><title>Conclusions/Significance</title><p>Horse might be a useful potential candidate for an animal model of depression. Face validity of this model appeared good, and potential genetic input and high prevalence of these disorders in females add to the convergence. At a time when current animal models of depression are questioned and the need for novel models is expressed, this study suggests that novel models and biomarkers could emerge from ethological approaches in home environments.</p></sec>
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Lansade, L., Colson, V., Parias, C., Trösch, M., Reigner, F., & Calandreau, L. (2020). Female horses spontaneously identify a photograph of their keeper, last seen six months previously. Scientific Reports, 10(1), 6302.
Abstract: Horses are capable of identifying individual conspecifics based on olfactory, auditory or visual cues. However, this raises the questions of their ability to recognize human beings and on the basis of what cues. This study investigated whether horses could differentiate between a familiar and unfamiliar human from photographs of faces. Eleven horses were trained on a discrimination task using a computer-controlled screen, on which two photographs were presented simultaneously (32 trials/session): touching one was rewarded (S+) and the other not (S-). In the training phase, the S+ faces were of four unfamiliar people which gradually became familiar over the trials. The S- faces were novel for each trial. After the training phase, the faces of the horses' keepers were presented opposite novel faces to test whether the horses could identify the former spontaneously. A reward was given whichever face was touched to avoid any possible learning effect. Horses touched the faces of keepers significantly more than chance, whether it was their current keeper or one they had not seen for six months (t = 3.65; p < 0.004 and t = 6.24; p < 0.0001). Overall, these results show that horses have advanced human face-recognition abilities and a long-term memory of those human faces.
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h:, M., Lévy, F., Fortin, M., Leterrier, C., & LansadLansade, L. (2013). Stress and temperament affect working memory performance for disappearing food in horses, Equus caballus. Animal Behaviour, 86(6), 1233–1240.
Abstract: In the present study, we sought to determine the influence of stress and temperament on working memory for disappearing food in horses. After assessment of five dimensions of temperament, we tested working memory of horses using a delayed-response task requiring a choice between two food locations. Delays ranging from 0 to 20 s were tested. The duration of working memory for disappearing food was first characterized without stressors (N = 26). The horses were then divided into two groups and their performance was assessed under stressful (exposure to acute stressors prior to testing, N = 12) or control conditions (N = 12). Results showed that the duration of working memory for disappearing food lasted at least 20 s under nonstressful conditions, and that under stressful conditions this duration lasted less than 12 s. This stress-induced impairment confirms in a nonrodent species that working memory performance is very sensitive to exposure to stressors. In addition, working memory performance in horses is influenced by the temperamental dimension of fearfulness according to the state of stress: fearful horses showed better performance under control conditions and worse performance under stressful conditions than nonfearful horses. These findings are discussed in the context of the Yerkes–Dodson law of stress and performance.
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Valenchon, M., Lévy, F., Górecka-Bruzda, A., Calandreau, L., & Lansade, L. (2013). Characterization of long-term memory, resistance to extinction, and influence of temperament during two instrumental tasks in horses. Animal Cognition, 16(6), 1001–1006.
Abstract: The present study investigated the influence of temperament on long-term recall and extinction of 2 instrumental tasks in 26 horses. In the first task (backward task), horses learned to walk backward, using commands given by an experimenter, in order to obtain a food reward. In the second task (active avoidance task), horses had to cross an obstacle after a bell rang in order to avoid emission of an air puff. Twenty-two months after acquisition, horses exhibited perfect recall performance in both tasks. Accordingly, no influence of temperament on recall performance could be observed for either task. In contrast, in the absence of positive or negative outcomes, the horses’ ability to extinguish their response to either task was highly variable. Resistance to extinction was related to some indicators of temperament: The most fearful horses tended to be the most resistant to extinction in the backward task, while the least sensitive horses tended to be the most resistant to extinction in the active avoidance task. These findings reveal extensive long-term memory abilities in horses and suggest an influence of temperament on learning processes other than acquisition.
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Trösch, M., Pellon, S., Cuzol, F., Parias, C., Nowak, R., Calandreau, L., et al. (2020). Horses feel emotions when they watch positive and negative horse-human interactions in a video and transpose what they saw to real life. Anim. Cogn., 23(4), 643–653.
Abstract: Animals can indirectly gather meaningful information about other individuals by eavesdropping on their third-party interactions. In particular, eavesdropping can be used to indirectly attribute a negative or positive valence to an individual and to adjust one's future behavior towards that individual. Few studies have focused on this ability in nonhuman animals, especially in nonprimate species. Here, we investigated this ability for the first time in domestic horses (Equus caballus) by projecting videos of positive and negative interactions between an unknown human experimenter (a “positive” experimenter or a “negative” experimenter) and an actor horse. The horses reacted emotionally while watching the videos, expressing behavioral (facial expressions and contact-seeking behavior) and physiological (heart rate) cues of positive emotions while watching the positive video and of negative emotions while watching the negative video. This result shows that the horses perceived the content of the videos and suggests an emotional contagion between the actor horse and the subjects. After the videos were projected, the horses took a choice test, facing the positive and negative experimenters in real life. The horses successfully used the interactions seen in the videos to discriminate between the experimenters. They touched the negative experimenter significantly more, which seems counterintuitive but can be interpreted as an appeasement attempt, based on the existing literature. This result suggests that horses can indirectly attribute a valence to a human experimenter by eavesdropping on a previous third-party interaction with a conspecific.
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Lansade, L., Pichard, G., & Leconte, M. (2008). Sensory sensitivities: Components of a horse's temperament dimension. Appl. Anim. Behav. Sci., 114(3-4), 534–553.
Abstract: Temperament is an important factor when working with horses. Behavioural tests have already been developed to measure certain dimensions of a horse's temperament (fearfulness, gregariousness, etc.). In order to measure the temperament more precisely, our work aimed to identify a dimension which has already been described in several species but not yet in horses, namely sensory sensitivity. Our study was based on the definition of a temperament dimension as “a behavioural characteristic stable across situations and over time”. We designed several tests for each sense and then determined whether the responses observed were correlated between situations and in time. The principle of the tests was to generate two stimuli of different intensities for each sense (e.g. two different sounds) and to measure the intensity of the horse's response (N = 26). Using Spearman rank correlations, we tested whether the responses to these different stimuli were inter-correlated. We repeated the same tests 5 months later to determine whether the responses were correlated over time. Within each sense, results show that the greater the horses' response to one stimulus, the greater their response to the other. For example, the reaction to the odour of cinnamon (time spent near the source of the odour) was significantly correlated to the reaction to lavender (R = 0.53, p = 0.004). The reactions to two different sounds or to two different tactile stimuli (von Frey filaments, or contact of a brush on the body), were also significantly correlated (R = 0.59, p < 0.0001; R = 0.38, p = 0.029). Finally, the reactions to two different tastes or to two visual stimuli tended to be correlated (R = 0.27, p = 0.09; R = 0.27, p = 0.09). However, there was no significant correlation between the responses to stimuli relating to different senses. Finally, except for the responses to odour, the responses to other sensory stimuli showed stability over a 5-month period (e.g. tactile stimulation: R = 0.71, p < 0.0001). In conclusion, our study revealed characteristics which were stable across situations and over time. The absence of links between the characteristics measured for the different senses suggests that a dimension for each sense exists (e.g. tactile sensitivity) rather than a general sensory sensitivity dimension covering all the senses.
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Lansade, L., & Bouissou, M. - F. (2008). Reactivity to humans: A temperament trait of horses which is stable across time and situations. Appl. Anim. Behav. Sci., 114(3-4), 492–508.
Abstract: The aim of this study was to test the existence of a “reactivity-to-humans” trait which is stable over time and across situations. For this purpose, four test situations were repeated on the same animals at 8 months, 1.5 years (N = 110 horses) and 2.5 years of age (N = 54 horses). These situations involved a “familiar passive human test” during which a familiar person stayed motionless in the test pen, a “familiar active human test” and an “unfamiliar active human test” during which a familiar or unfamiliar person attempted to touch the horse, and a “halter-fitting and heart-rate measurement test”, during which the horse was haltered and equipped with a surcingle and then had its heart-rate measured. Many behavioural variables were recorded during the tests, and correlations between ages and variables measured during other situations were investigated. When correlations were found, we concluded that the variables corresponded to temperament traits which are stable over time and across situations. The horses tested were divided into four groups according to breed (Anglo-Arab and Welsh) and year of birth (2001 and 2002). Data for each group were analysed separately with Spearman rank correlations. Regarding stability over time, there was a strong correlation between ages in the frequency of licking/nibbling the passive human, the time taken by a familiar or unfamiliar person to touch the horse, and the time taken to fit a halter (e.g. the time taken to touch the horse's muzzle was significantly correlated between ages in 7 out of the 8 possible cases: 0.40 <= R <= 0.67). Regarding stability across situations, results indicate that the more frequently a horse sniffed, licked or nibbled a passive human, the easier it was for either a familiar or unfamiliar active human to touch and halter it. Moreover, a horse which could be touched easily by a familiar human could also be touched and haltered easily by an unfamiliar human. These behaviours, which are linked directly to humans, therefore indicate good stability over time and across situations. In conclusion, this stability suggests the existence of a “reactivity-to-humans” temperament trait, whether the human is passive or active, familiar or unfamiliar. When the animals do not have frequent contact with humans, this reactivity is stable over time and can be measured as early as 8 months of age using the behavioural variables cited above.
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Lansade, L., Bouissou, M. - F., & Erhard, H. W. (2008). Reactivity to isolation and association with conspecifics: A temperament trait stable across time and situations. Appl. Anim. Behav. Sci., 106(2-4), 355–373.
Abstract: A temperament trait is generally defined as individual differences in behaviour that are present early in life and relatively stable across situations and over time. The aim of this study was to test the existence of a trait <<gregariousness>> in horses, by testing the stability across situations and over time of the responses to different social events. Sixty-six Welsh ponies and 44 Anglo-Arab horses were successively tested at 8 months and 1.5 years of age. Among them, 33 ponies and 21 horses were also tested at 2.5 years of age. They were submitted to four test situations: isolation and separation from, attraction towards and passing conspecifics. We carried out the analysis using each of four test groups as a unit (e.g. 33 Welsh ponies born in 2001, tested in isolation). Isolation and separation stood out as tests that showed a high consistency within test, across tests and across time. The most interesting behavioural parameter was the frequency of neighing, which was well correlated with other parameters measured in the same tests, such as defecation, locomotion and vigilance, as well as across the 3 years (e.g. for separation test: 0.41 < R < 0.61). Therefore, the behaviour of neighing observed in separation or isolation tests as early as 8 months of age appears to be a good indicator of similar behaviour in similar situations later in life, but also of other behaviours which can render the horse difficult to use. No parameter recorded during the attraction test presented stability across situations and time: the reactions to this test were not the expression of a stable characteristic of the individual and did not reflect the same characteristic as the three other tests. Of the different parameters recorded during the passing conspecifics test, the time to cross the arrival line near conspecifics showed good stability across years (0.35 < R < 0.68). This parameter was also correlated with many others recorded during the same test, and also, to a certain extent, to the frequency of neighing in the isolation and separation tests. This stability across responses expressed in various social contexts, and this stability over time, from 8 months to 2.5 years of age suggest the existence of a trait of gregariousness in the horse. From a practical point of view, that means it is possible to estimate the level of gregariousness of a horse as early as 8 months of age. Furthermore, additional analysis shows that gregariousness decreases with age.
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Lansade, L., Bouissou, M. - F., & Erhard, H. W. (2008). Fearfulness in horses: A temperament trait stable across time and situations. Appl. Anim. Behav. Sci., 115(3-4), 182–200.
Abstract: The purpose of this study was to test the existence of a “fearfulness” trait in horses, by testing the stability across situations and over time of the responses to different fear-eliciting situations. It was also to identify which behavioural parameters are the best indicators of this trait. Sixty-six Welsh ponies and 44 Anglo-Arab horses were successively tested at 8 months and 1.5 years of age. Of these, 33 Welsh ponies and 21 Anglo-Arabs were also tested at 2.5 years of age. At each age, they were subjected to four test situations. The first test involved the introduction of a novel object in the test pen (novel object test). In the second test, a novel area was placed in the pen between the horse and a bucket of food, to determine the time the horse took to cross the area (novel area test). Finally, the third test consisted in suddenly opening an umbrella in front of the horse while it was eating (surprise test). During these tests, many behavioural parameters were recorded. A fourth test consisted of a surprise test during which the horse was held by a handler while its heart rate was measured. Spearman correlations were used to identify links between behavioural parameters measured during different tests and between different ages. Reactions to the first three tests showed consistency between them and over time. Among all the behavioural parameters measured during these tests, some presented high stability over time and were well correlated with behaviours expressed during other tests, indicating they are the best indicators of a fearfulness trait: the frequency of licking/nibbling the novel object, the time to put one foot on the novel area and to eat from a bucket placed just behind it, and the flight distance and the time to eat under the opened umbrella. The stability across responses expressed in various fear-eliciting events and over time from 8 months to 2.5 years of age suggests the existence of a [`]fearfulness' trait in horses. The different indexes of heart rate measured or calculated during the surprise effect present limited stability over time and almost no correlation with the behavioural parameters measured during the other three tests. We conclude that, in contrast to the previously mentioned behaviours, these are not reliable measures of a temperament trait. From a practical point of view, this study shows that it is possible to identify a horse's level of fearfulness as early as 8 months of age using the first three tests.
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