Pigs are among the most cognitively sophisticated farmed animals, with intelligence comparable to dogs and young children. This cognitive complexity has direct implications for how their welfare should be evaluated and protected.
The cognitive sophistication of pigs demands that their welfare be evaluated in terms of mental states, not just physical conditions. A pig in a barren gestation crate is not merely physically restricted; it is a highly intelligent social animal in a state of profound cognitive deprivation. The judgment bias studies by Mendl and colleagues elegantly demonstrate that pigs in poor welfare conditions show pessimistic cognitive biases: they interpret ambiguous signals as negative, mirroring the relationship between depression and pessimism in humans. This research transforms the welfare case from physical harm to psychological suffering, with significant implications for how we should evaluate and regulate pig farming systems.