In affective science, the positive or negative quality of an emotional state.

Positive valence states (curiosity, contentment, anticipation of reward, social engagement, play) are welfare-positive. Negative valence states (fear, anxiety, frustration, depression, pain) are welfare-negative. The dimension captures the felt quality of the emotional state, distinct from the level of physiological activation.

Valence is one of the two main dimensions used in affective state assessment, the other being arousal. The combination of valence and arousal allows a more nuanced picture than simple measures of stress alone. An animal can be in high arousal with positive valence (excitement, play), high arousal with negative valence (fear, anxiety), low arousal with positive valence (contentment, relaxation), or low arousal with negative valence (depression, withdrawal).

Assessing valence in non-verbal animals requires behavioural and physiological indicators that distinguish between positive and negative emotional states. This is more difficult than assessing arousal alone, because high arousal looks broadly similar regardless of valence (raised heart rate, increased activity, alertness) but the welfare implications are very different.

Modern welfare research uses a range of valence-sensitive measures including approach versus avoidance behaviour, anticipatory behaviour patterns, cognitive bias testing (where the animal’s interpretation of ambiguous information reveals their current valence), and facial expression coding (which has been developed for several species including horses, sheep, and cats).

The concept matters for welfare practice because welfare-positive management aims not just to reduce negative-valence states but to support positive-valence states. An animal whose life is free of obvious suffering but who lacks positive experiences is not in full welfare. Modern welfare science treats the cultivation of positive valence as part of the welfare goal, not just the avoidance of negative valence.