Chin rub CRs are elicited by flavors associated with apomorphine, scopolamine, methscopolamine, physostigmine and neostigmine.

Three experiments were conducted in order to determine the pattern of behavioral conditioned responses (CRs) elicited by flavors paired with each of various drugs which effectively establish avoidance of a flavored solution. Each of the drugs employed supported both chin rub CRs and avoidance of a flavored solution. Experiment 1 employed apomorphine, a classic emetic agent which pharmacologically acts as a dopaminergic agonist. Experiment 2 and 3 employed cholinergic agonists and antagonists which were either peripherally or both peripherally and centrally acting agents. The results suggest that chin rub CRs may be produced by means of the activation of a system which is peripheral to the CNS. Furthermore, flavor avoidance produced by drugs which support chin rub CRs may be mediated by a shift in the hedonic rating of the flavored solution; whereas, flavor avoidance produced by drugs which do not support chin rub CRs is probably mediated by a mechanism other than a hedonic shift.