Shedding light: an evidence-based approach to adapting cognitive bias tests for reptiles

Quantifying animals' subjective experiences, or affective states, has become an increasing focus within welfare science. Physiological measures can reliably detect emotional arousal, but assessing valence, whether an experience is positive or negative, remains challenging. Behavioural indicators can assist in this regard, yet they often require species-specific interpretation and may introduce observer bias. These difficulties are compounded when working with relatively understudied taxa such as reptiles. Cognitive bias tests, particularly attention and judgement bias paradigms, provide a promising approach for assessing affect. Attention bias tests are rapid, cost-effective and require minimal training, whereas judgement bias tests, although more time-intensive, can detect subtle shifts in affect and can be repeated over time to monitor long-term changes. Despite their potential, few studies have applied these methods to reptiles, and necessary species-specific adaptations remain largely untested. Pilot studies are therefore essential to establish learning rates, identify effective cues and determine motivational preferences across reptile species. Developing a clearer link between cognitive bias and welfare outcomes will also be important. Given the increasing number of reptiles housed in private and professional settings, there is a pressing need for robust empirical tools to assess their welfare. Cognitive bias testing represents a promising and underused method that could significantly advance welfare science in reptiles.