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.

Abstract: Persistence of individual differences in animal behavior in reactions to various environmental challenges could reflect basic divergences in temperament, which might be used to predict details of adaptive response. Although studies have been carried out on fear and anxiety in various species, including laboratory, domestic and wild animals, no consistent definition of fearfulness as a basic trait of temperament has emerged. After a classification of the events that may produce a state of fear, this article describes the great variability in behavior and in physiological patterns generally associated with emotional reactivity. The difficulties of proposing fearfulness-the general capacity to react to a variety of potentially threatening situations-as a valid basic internal variable are then discussed. Although there are many studies showing covariation among the psychobiological responses to different environmental challenges, other studies find no such correlations and raise doubts about the interpretation of fearfulness as a basic personality trait. After a critical assessment of methodologies used in fear and anxiety studies, it is suggested that discrepancies among results are mainly due to the modulation of emotional responses in animals, which depend on numerous genetic and epigenetic factors. It is difficult to compare results obtained by different methods from animals reared under various conditions and with different genetic origins. The concept of fearfulness as an inner trait is best supported by two kinds of investigations. First, an experimental approach combining ethology and experimental psychology produces undeniable indicators of emotional reactivity. Second, genetic lines selected for psychobiological traits prove useful in establishing between behavioral and neuroendocrine aspects of emotional reactivity. It is suggested that fearfulness could be considered a basic feature of the temperament of each individual, one that predisposes it to respond similarly to a variety of potentially alarming challenges, but is nevertheless continually modulated during development by the interaction of genetic traits of reactivity with environmental factors, particularly in the juvenile period. Such interaction may explain much of the interindividual variability observed in adaptive responses.

Abstract: The notion that tool-use is unique to humans has long been refuted by the growing number of observations of animals using tools across various contexts. Yet, the mechanisms behind the emergence and sustenance of these tool-use repertoires are still heavily debated. We argue that the current animal behaviour literature is biased towards a social learning approach, in which animal, and in particular primate, tool-use repertoires are thought to require social learning mechanisms (copying variants of social learning are most often invoked). However, concrete evidence for a widespread dependency on social learning is still lacking. On the other hand, a growing body of observational and experimental data demonstrates that various animal species are capable of acquiring the forms of their tool-use behaviours via individual learning, with (non-copying) social learning regulating the frequencies of the behavioural forms within (and, indirectly, between) groups. As a first outline of the extent of the role of individual learning in animal tool-use, a literature review of reports of the spontaneous acquisition of animal tool-use behaviours was carried out across observational and experimental studies. The results of this review suggest that perhaps due to the pervasive focus on social learning in the literature, accounts of the individual learning of tool-use forms by naïve animals may have been largely overlooked, and their importance under-examined.