In the study, aversive and appetitive reinforcers were used in distinct yet complementary ways to drive learning in Mongolian gerbils during a tone-conditioned hurdle crossing task in a shuttle box.

Aversive Reinforcers (Footshock, FS):

• Aversive reinforcers, specifically footshocks, were administered to the gerbils when they failed to perform the desired conditioned response (CR) within a given timeframe.
• The footshock served as a punishment for unsuccessful trials, thereby motivating the animals to avoid the negative stimulus by performing the CR (hurdle crossing).
• It was observed that aversive reinforcement played a crucial role in the initial acquisition of the conditioned behavior. Gerbils quickly learned to avoid the footshock by performing the hurdle crossing more efficiently during the early sessions of training.

Appetitive Reinforcers (Brain Stimulation Reward, BSR):

• Appetitive reinforcers were administered in the form of brain stimulation rewards. Electrical stimulation of the ventral tegmental area (VTA) provided a positive reward when the gerbils successfully performed the CR.
• This type of reinforcement was used to encourage and maintain high levels of performance. Successful hurdle crossings were immediately followed by the BSR, reinforcing the correct behavior.
• The study found that while aversive reinforcers were effective for initial learning, the appetitive reinforcers were more effective in maintaining the learned behavior over time.

Combined Reinforcement:

• The combination of both aversive and appetitive reinforcers led to the fastest acquisition and highest performance levels. Each successful trial was rewarded with BSR, while unsuccessful trials were punished with FS.
• This combined approach resulted in significantly higher CR rates during the early acquisition sessions compared to groups receiving only one type of reinforcement.
• When one type of reinforcer was omitted after training with the combined reinforcement schedule, clear changes in CR rates were observed. Omission of FS decreased CR rates, but omission of BSR did not have the same effect, indicating different roles of these reinforcers in maintaining learned behaviors.

Key Findings

• The study demonstrated that aversive reinforcers were more effective for the initial acquisition of conditioned responses, while appetitive reinforcers were crucial for maintaining these responses over time.
• Combining both types of reinforcers facilitated faster learning and higher performance levels compared to using either reinforcer alone.
• The study provided insights into how the interaction of reward and punishment can optimize learning processes, supporting the hypothesis that both reinforcers contribute to a convergent learning effect.

These results suggest that in learning paradigms, strategically combining aversive and appetitive reinforcers can lead to more effective and robust learning outcomes. The differential roles of these reinforcers highlight the importance of considering both punishment and reward in designing training and rehabilitation programs .