Increase in left-side oriented behaviours associated to negative emotions in captive Asian elephants

The role of each hemisphere of the brain in the perception, production and expression of emotions remains a topic of controversy. Based on asymmetries found through neurological and behavioural studies on both human and non-human animals, several hypotheses and theories have been proposed regarding emotional processing. To contribute to this ongoing discussion and get insights on elephant emotional processing, the present study investigates whether the right hemisphere is more activated during negative emotions in Asian elephants (Elephas maximus). Non-invasive behavioural observations using a video-camera were conducted for 70 h on captive individuals. Using all-occurrences sampling, the side of the body (left or right) to which five self-directed behaviours were oriented was performed on each individual. To investigate the relationship between behavioural laterality and emotional valence, post-conflict behavioural sides were compared to baseline ones in three victims of aggression. Results revealed that, after receiving an aggression, the odds of left side-oriented behaviours significantly increased by 1.82 times when compared to baseline levels. These findings suggest a greater involvement of the right hemisphere in negative emotional processing, aligning with previously proposed theories. Overall, this study may contribute to the understanding of emotional processing in elephants and comparative research on brain asymmetry.