The science of animal welfare has developed increasingly sophisticated tools for measuring animal states, moving beyond behavior to include physiology, cognition, and positive experience.
Early animal welfare science focused primarily on preventing negative states including pain and fear. Modern welfare science recognizes that the absence of suffering is insufficient — animals should also have opportunities to experience positive states including pleasure, play, and social bonding. Judgement bias testing, which measures whether animals interpret ambiguous cues optimistically or pessimistically, provides a validated tool for assessing overall affective state that correlates with welfare interventions. This positive welfare framework has transformative implications for housing and management standards.