SS WERE 15 15-17 YR. OLD HIGH SCHOOL STUDENTS. GSR WAS CONDITIONED TO A BLUE LIGHT (CS+) USING MILD SHOCK AS UCS AND A 50% REINFORCEMENT SCHEDULE, WHILE A YELLOW LIGHT (CS-) WAS PRESENTED AN EQUAL NUMBER OF TIMES WITHOUT REINFORCEMENT. AFTER CONDITIONING WAS ESTABLISHED, INSTRUCTIONS DESIGNED TO REVERSE THE SIGNIFICANCE OF CS+ AND CS- WERE GIVEN, FOLLOWED BY A TEST SERIES WITH BOTH STIMULI UNREINFORCED. RESULTS SHOW A SUDDEN REVERSAL OF THE DIFFERENTIAL CONDITIONING, GSRS OF GREATER MAGNITUDE BEING EVOKED BY CS-. THESE NEW CRS DID NOT EXTINGUISH, BUT TENDED TO INCREASE IN MAGNITUDE OVER NONREINFORCED TEST TRIALS. A 2-COMPONENT THEORY OF AUTONOMIC CONDITIONING WAS NOT SUPPORTED; THE CR APPEARED TO BE FULLY ASCRIBABLE TO SS' ANTICIPATION OF SHOCK. (PsycINFO Database Record (c) 2006 APA, all rights reserved)