Step Aside! Assessing Body Awareness In Pigs Using A Body-As-An-Obstacle Task

Body awareness allows animals to perceive their own body as a tool or even an obstacle when interacting with their environment. Body-as-an-obstacle tasks have been employed to test body awareness in human infants, elephants, and dogs. Investigating body awareness in a farm animal species for the first time, we tested young domestic pigs (Sus scrofa domesticus, N = 17, 8 male and 9 female, 7 weeks old) in a modified body-as-an-obstacle task. Pigs learned to push a sliding panel with their snout to access food rewards. This was achievable from two different positions: left or right, corresponding to on or off a mat. In the test condition, the mat on which pigs were positioned was attached to the panel via a chain. If body-aware, pigs were expected, after unsuccessfully trying from the mat side, to step off the mat and push from the other side. Subjects stepped off the mat and solved 52% of the “attached” trials. Additionally, they were significantly quicker, and more likely, to push from the other side after stepping off in this condition than when an external obstacle visibly blocked the panel from behind. However, pigs’ behavior in a newly introduced control condition, in which the panel was blocked for a reason unknown to the pig, did not differ significantly from that in the attached condition. Hence, similar to previously tested species, pigs can flexibly adjust their behavior to solve a body-as-an-obstacle task. Importantly, our findings also highlight the necessity of determining whether animals simply switch strategies and, thereby, succeed in body-as-an-obstacle tasks whenever they cannot identify the reason for the obstruction, or whether their success indeed constitutes evidence for body awareness.