Three groups of rats were trained in a step-down passive avoidance situation in which Ss terminated shock when they failed to inhibit for 60 sec by escaping into a distinctive postshock compartment. The groups spent 5, 15, or 90 sec in the safe compartment but all had the same 50-min ITI. As predicted, inhibition was inversely related to time spent in the safe area. A second experiment was a 2 × 2 × 2 factorial with sex, postshock confinement (5 vs. 90 sec), and similarity of the postshock and platform areas as variables. Again the longer postshock period retarded passive avoidance, this time when the ITI approximated the confinement interval. Similarity of the two regions was not a relevant variable, casting doubt on an extinction of fear hypothesis and providing support for the interpretation that long postshock confinements produce poor performance in passive avoidance because they increase the approach value of the safe region (relaxation, or relief, theory).