Funder and dates: PhD studenship funded by SRUC and INRA, 2013-2017
Collaborators and partners: SRUC and INRA
Animals are capable of experiencing emotions. The expression of emotions involves changes in posture, vocalisations, odours and facial expressions. These changes can be perceived and used as indicators of emotional state by other animals. Since emotions can be perceived by conspecifics, understanding how emotions are identified and how they can spread within a social group is essential for improving the welfare of farmed species, which are mostly reared in groups. Studies in humans have shown that depressed patients are more likely than healthy patients to interpret neutral faces as showing sadness, and are less able to recognise anger. Animals in similar conditions may fail to recognise aggressiveness or pain in others and fail to respond appropriately, with obvious consequences for welfare. A recent method developed for the evaluation of emotions in animals is based on judgment biases, i.e. an individual in a negative emotional state will show pessimistic judgments while an individual in a positive emotional state will show optimistic judgments. The aims of this project were to establish whether sheep and goats can discriminate between images of faces of familiar conspecifics taken in positive and negative situations, and whether sheep and goats perceive the valence (positive of negative) of the emotion expressed by the animal on the image. The potential use of images of faces in cognitive bias studies was also investigated.
We showed that sheep and goats could discriminate between images of faces of conspecifics taken in different situations (positive v. negative and neutral v. negative). Overall, animals were more attentive towards images or videos of conspecifics in negative situation, i.e. presumably in a negative emotional state, which suggests that sheep and goats are able to perceive the emotion expressed. The identity of the individual on the photo also affected the animals’ spontaneous reaction to the images. Social relationships such as dominance between the tested and photographed individual seem to influence emotion perception. Further studies are needed to reach a definite conclusion on the use of images of faces in cognitive bias methodology.