Cognitive bias testing in pigs reveals their underlying emotional states, with optimistic decision-making under ambiguity indicating positive welfare and pessimistic responses indicating negative welfare.
Cognitive bias testing represents a scientific breakthrough in welfare assessment because it provides a window into the subjective emotional state of animals that behavioral observation alone cannot reliably reveal. A pig can appear calm and non-stereotypic while experiencing chronic negative affect — cognitive bias testing can detect this. Conversely, pigs in genuinely positive welfare conditions make faster, more confident approach responses to ambiguous stimuli, demonstrating the optimistic orientation associated with positive emotional states. The welfare implications are profound: if we can reliably measure emotional valence in pigs, we can compare housing systems not just on what behaviors are absent but on whether animals experience positive states. This shifts welfare assessment from harm prevention to positive welfare promotion.