In the study of animal behavior, any detectable change or signal in the environment that evokes a physiological or behavioral response in an organism is formally defined as a(n) _____.

The slides describe the call or whistle as a **stimulus** that animals learn is related to feeding, which serves as the reward. This example shows that communication-related behavior can be learned through an association between a sound and a subsequent event.\n\n**Key takeaway:** A producer's sound can become a learned predictor of feeding.\n\n**Glossary:** **Stimulus**: An event or signal that can elicit or predict a response; **reward**: An outcome associated with a learned response.