The collateral pretraining of spaced responding

Long Evans rats obtained a high frequency of reinforcement during initial exposure to a schedule which reinforced only responses spaced by at least 10 sec (DRL 10) provided this schedule was part of a two lever concurrent Fixed Ratio-DRL 10 schedule on which (1) the animal had received Fixed Ratio pretraining and (2) the animal needed 10 or more sec to complete the ratio requirement. Subsequent removal of the ratio lever resulted in marked disruption of spaced responding, although removal of Fixed Ratio reinforcement did not affect spaced responding.