Behavioral Evidence of Felt Emotions: Approaches, Inferences, and Refinements

Felt emotional states are at the very heart of many concerns about animal welfare. However, some scholars express doubt that animals are able to have such experiences, and there is much debate about what types of evidence can be used to draw inferences regarding such feelings in animals. The objective of this review is to critically examine inferences regarding felt negative emotions in animals based on various types of experimental and observational evidence resulting from behavioral studies. This review takes three types of approach: the assessment of spontaneous responses to a noxious stimulus, changes in these responses following a drug treatment, and assessments of the animal's motivation to avoid the stimulus. In each case we provide examples from previous experiments and suggest refinements that overcome certain limitations to each approach. We suggest that studies using learned, flexible, context-dependent responses, and tasks involving discrimination and generalization of affective states induced by drugs may be especially useful. Although the various types of evidence can be used in combination to draw tentative inferences, conclusions regarding felt emotions still fall short of definitive. As an approach forward, we propose adopting an Affective Stance that posits specific felt emotions and tests the predictions that arise from this posit that are not predicted by other approaches to this issue.