Relative time in dangerous and safe places influences one-way avoidance learning in the rat

This paper reports three experiments on one-way avoidance learning in rats which examined the effect of time spent in the safe and dangerous compartments on acquisition, maintenance, and extinction of avoidance. In Experiment 1 time spent in safety was manipulated, and time spent in danger was held constant. Animals spending more time in safety needed fewer trials to reach the acquisition criteria and more trials to reach the extinction criteria; both effects became stronger as the required criteria for acquisition and extinction were increased. In Experiment 2 time spent in safety/danger was manipulated while holding the intertrial interval constant. Groups simultaneously spending more time in safety and less time in danger again needed fewer trials to reach the learning criteria. In Experiment 3 time spent in danger was manipulated, whereas time spent in safety was held constant. Groups spending less time in danger needed fewer trials to reach the learning criteria. These results indicate that the magnitude of the reinforcement or incentive value of the safety compartment is not a linear function of absolute time spent therein, but a function of the ratio between the length of time spent in safety and in danger.