Animal welfare science employs diverse research methods to assess the subjective experiences of animals, with methodological advances enabling more nuanced welfare assessment.
Welfare science has developed increasingly sophisticated methods for assessing animal subjective states that go beyond simple stress measures. Cognitive bias tests, adapted from human psychology, can reveal whether animals are in generally positive or negative affective states. Qualitative behaviour assessment using observer-rated behavioural expressions has proven surprisingly reliable across species and assessors. Combined multi-domain welfare assessment incorporating health, behaviour, and physiology provides the most comprehensive picture of animal welfare status.