This project has two major objectives: (1) a systematic exploration of the effects of various cardiotropic drugs on cardiac activity, with heart rate under control of either environmental conditional stimuli or a cardiac pacemaker; and, (2) the behavioral effects of "aversive reinforcement" schedules specified within a general theory of stimulus schedules. One line of research we are projecting now aims at the blood pressure and heart rate changes produced by parametric manipulation of the temporal relationship between conditional and unconditional stimuli in the Pavlovian conditioning paradigm. This study will serve to integrate and extend previous work by placing conditioning paradigms such as trace, delay and backward conditioning, and positive, negative, and intermediate CS-UCS contingencies along a temporal continuum. We expect to examine the beat-by-beat phase relations between heart rate and blood pressure, as well as to assess the relative contributions of sympathetic and parasympathetic innervations to the cardiac CR through the use of several cardiotropic agents. These agents will also be administered during the period of acquisition of the cardiac CR so as to disclose the relative roles and time course of involvement of the sympathetic and parasympathetic innervations in that acquisition. We also plan to explore the variable of "response contingency" in a series of schedules ranging between free-operant avoidance and punishment by specifying probabilities of electric shock delivery for responding and for non-responding. We anticipate that the resulting family of functions would provide a systematic and reasonably exhaustive description of the behavioral effects of "contingent" and "non- contingent" deliveries of S-R.