Changes of intertrial response rate with elapse of time after two-way avoidance trial in rats

The changes of intertrial response (ITR) rate along the intertrial interval duration were examined in 30 rats trained in two-way avoidance. The lowest ITR rate was observed just after a cross-through response terminating a trial. Rats trained with a warning signal of darkness showed over-all higher ITR rates and shorter periods of post-trial reduction of ITR rate than rats trained with a more salient noise warning signal. The period of post-trial low ITR rate lengthened in consecutive sessions indicating the gradual development of a safety state.