Negative reinforcement of behavioral variability without previous training with positive reinforcement

In a previous study, Fonseca Júnior and Hunziker (2017) provided evidence of the control of behavioral variability by avoidance contingencies. However, their study presented three methodological weaknesses: (1) only one contingency reversal was conducted in the experimental design adopted, (2) the lever press was shaped using a positive reinforcement procedure, and (3) the intermittency of reinforcement between Lag n and Yoke conditions was not successfully equaled. The present study aimed to overcome these three methodological limitations. Three experimentally naive male rats with no prior history with positive reinforcement had sequences of three lever presses between two levers negatively reinforced under the following discrete trial avoidance contingencies that provided similar intermittency of reinforcement: Lag 1, Yoke, Lag 1, and Yoke. All subjects showed high levels of behavioral variability under the Lag 1 contingency and decreased levels of behavioral variability under the Yoke contingency. These results replicate the findings of Fonseca Júnior and Hunziker, suggesting that behavioral variability can be controlled by avoidance contingency without previous exposure to positive reinforcement. Moreover, these findings suggest that the high levels of variation obtained under the Lag n condition are an effect of operant contingency and not a mere byproduct of the intermittency of reinforcement.