Functional lateralization in domestic pigs (Sus scrofa): Interactions with emotions and personality

• Applicants: Dr. Sandra Düpjan; Dr. Lisette Leliveld
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry ; Sensory and Behavioural Biology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 261381965

Understanding animal emotions is crucial to the evaluation of animal welfare. Emerging evidence shows that emotional processing can be lateralized in both human and non-human animals, i.e. there are functional asymmetries of the hemispheres. However, in farm animals, such evidence is still rare. Cerebral lateralization of emotional processing works in two ways: on the one hand, individual lateralization patterns as expressed through, for example, handedness can be associated with distinct patterns of emotional processing like trait anxiety. Such individually distinct patterns of emotional reactivity are also referred to as personality. On the other hand, hemispheric specialization can occur for different affective states, with a left hemisphere dominance for responding to food rewards, and a right hemisphere dominance for fear and aggression. Up to date, little is known about lateralized processing in domestic pigs, which is one of the most important farm animal species. There are no means of measuring cerebral activity in the awake, freely moving pig. However, cerebral lateralization can be measured easily and non-invasively through behavioural observations of sensory or motor biases. The aim of this project is to investigate the complex interactions of cerebral lateralization, emotional processing, and personality in the domestic pig. All methods were developed in a series of preliminary studies, which proved the feasibility of the chosen approaches. In order to draw a comprehensive picture, olfactory, visual, and motor lateralization will be studied (work package 1). In the first two modalities, conditioning will be the method of choice to associate emotional valence with specific stimuli, while snout use (right or left side), foot preference and curling direction of the tail will be examined as putative indicators of motor lateralization. Motor lateralization will be considered in the context of dominance rank as well as established, standardized tests for coping style and anxiety/fearfulness. As the auditory modality is known to play a dominant role in pig (emotional) communication, we decided to devote a separate work package (2) to study auditory emotional lateralization more extensively, i.e. across different emotional contexts. As opposed to the sensory modalities studied in work package 1, we will be able to use artificial (conditioned) as well as biologically relevant stimuli, i.e. porcine vocalizations. Bringing together evidence of lateralized processing of artificial as well as biological stimuli will strengthen results from work package 1 and thus the project as a whole.The two work packages combined will provide a comprehensive view of the complex interactions of emotion processing, lateralization and personality in the domestic pig. The knowledge we want to obtain shall help in future research on animal welfare as well as in the designing of animal-friendly housing and management.

• DFG Programme: Research Grants