Companion pigs alternate orientation between humans and snout-inaccessible targets

Previous research on intensely human-socialized pigs found no evidence for orientation alternations to direct human attention to an inaccessible target, the benchmark behaviour that in many other species has been reported to evidence capacity for functionally referential communication with humans. However, the unsolvable task paradigms that are typically used may mask communicative capacities by promoting manipulative behaviours in animals with strong independent problem-solving tendencies, like pigs. Here, using a novel out-of-reach paradigm that does not induce manipulative biases, we reassessed the capability of pigs for functionally referential communication with humans. We compared the emergence of orientation alternations between a human and an elevated, physically inaccessible target in adult companion pigs and dogs, a species characterized by more human-dependent problem-solving. We found that with these settings, pigs attempted to solve the task independently even less often than dogs and, similarly to dogs, pigs also exhibited orientation alternations. This is the first report demonstrating human-oriented functionally referential communicative behaviours in pigs, suggesting that this capacity may be more widespread across mammals than previously thought.