Effect of the passage of time on the contribution of initial response-outcome associations to instrumental performance

The effect of the passage of time on the contribution of initial response-outcome associations to subsequent instrumental performance was explored in three experiments with rats using outcome devaluation. Experiments 1 and 2 showed that a response that had been trained first with one outcome and then given identical training with a second outcome was more sensitive to devaluation of the second outcome than the first if the two training episodes were separated in time. Experiment 3 showed that inserting a delay between training with the second outcome and testing after outcome devaluation appeared to mitigate this effect of temporally separating first and second outcome training. Inserting this delay also made a response slightly more sensitive to devaluation of the first outcome than the second when there was no delay between the two training episodes. These results suggest that the passage of time can shift the balance between the contributions of first and second trained outcomes to instrumental performance.