In aversive conditioning experiments to treat alcohol addiction, every time a person drinks an alcoholic beverage, he or she also consumes a mixture that induces nausea. in classical-conditioning terminology, the nausea-inducing agent is the

In classical-conditioning terminology, the nausea-inducing agent is the unconditioned stimulus

In classical-conditioning terminology, unconditioned stimulus is described as  a response that triggered naturally without being controlled by our body, such as Nausea, pain that felt when we got pinched, being hungry every time we smell our mom's cooking, etc.