"Warmup" and "cooldown" in Sidman avoidance behavior of rats: A dual-process interpretation

The present experiment investigated relations between "warmup" in unsignalled Sidman avoidance in rats and the intensity of shock. Magnitude of shock-rate change was quantified by comparing the rat's behavior during the initial third and the final two thirds of the same session. Warmup was said to occur whenever the shock rate during the initial 20 min was higher than the shock rate during the final 40 min of a 60 min session. "Cooldown" was defined as lower shock rate during the initial 20 min than during the final 40 min. Warmup was observed when shocks were intense, cooldown was observed when shocks were low intensity, and neither was observed when medium-intensity shocks were administered. Response-rate changes were correlated with shock-rate changes, but were smaller. The results are interpreted within the framework of a dual-process theory of habituation.