THE LEVER-PRESSING RESPONSE BY RATS WAS PUNISHED ON AN INTERMITTENT SCHEDULE WITH BRIEF SHOCKS DURING A 15-MIN PERIOD AT THE BEGINNING OF EXTINCTION. IN EXP. I, TOTAL RESPONSES DURING BOTH THE PUNISHMENT PERIOD AND THE ENTIRE COURSE OF EXTINCTION WERE AN EXPONENTIAL DECREASING FUNCTION OF PUNISHMENT INTENSITY. IN EXP. II, PUNISHMENT (RESPONSE-CONTINGENT SHOCK) SUPPRESSED RESPONSE RATE MORE THAN NONCONTINGENT SHOCKS DURING A BRIEF PUNISHMENT PERIOD AND DURING SUBSEQUENT EXTINCTION SESSIONS. IN BOTH EXPERIMENTS, PUNISHMENT PRODUCED A PERMANENT REDUCTION IN THE NUMBER OF RESPONSES INSTEAD OF ONLY TEMPORARILY DEPRESSING RESPONSE RATE. (PsycINFO Database Record (c) 2006 APA, all rights reserved)