Measuring positive emotional states in laboratory primates has advanced significantly, providing welfare assessment tools that go beyond the absence of suffering to identify indicators of genuine wellbeing.
Positive welfare assessment for laboratory primates represents a genuine paradigm shift in how animal welfare is conceptualized. The original welfare framework focused on preventing negative states — pain, fear, distress, hunger. The positive welfare framework asks a further question: are animals experiencing positive states — pleasure, engagement, security, positive anticipation — that constitute a life worth living rather than merely a life without obvious suffering? For laboratory primates housed in adequate social conditions with appropriate enrichment, the positive welfare question is empirically answerable through behavioral and physiological measures. Judgment bias tasks that reveal cognitive optimism or pessimism provide a window into emotional valence that behavioral observation alone cannot capture. Institutions implementing positive welfare assessment develop more complete pictures of their animals welfare states and identify improvements that negative-indicator-only assessment would miss.