Matching by horses on several concurrent variable-interval schedules.

This research investigated the behavior of horses in responding to variable-interval schedules, a type of reinforcement schedule used in behavioral psychology. The researchers found that the horses’ relative rates of responding matched closely with the relative rates of reinforcement, validating the generality of the “matching law”, and giving additional insight into the response characteristics of horses.

Training the Horses

• The experiments involved three horses. Every horse was trained to press a response lever using its upper lip through a technique known as ‘successive approximations’—starting with easy steps and gradually increasing difficulty to achieve the desired outcome.
• Once the horses were successfully trained for the lip-press response, they spent several days on pre-training schedules. Pre-training included a continuous reinforcement schedule (a constant reward for the behaviour) and three variable-interval concurrent schedules: VI 15 sec VI 15 sec, VI 30 sec VI 30 sec, and VI 45 sec VI 45 sec. These involved alternating rewards at different time intervals.

Experiment Procedure

• Each horse was exposed to experimental sessions in their home stall daily until it received 60 grain reinforcers. A reinforcer is a stimulus which strengthens or increases the probability of a specific response.
• For the experiments, the horses were subjected to five different variable-interval schedules: VI 30-sec VI 90-sec, VI 45-sec VI 75-sec, VI 60-sec VI 60-sec, VI 75-sec VI 45-sec, and VI 90-sec VI 30-sec.

Results and Conclusion

• The results showed a strong matching relationship between the horses’ relative response rates and the relative rates of reinforcement. This result confirmed previously conducted experiments and indicated that the matching law also applies to horses.
• Regression modeling was used to analyze the data, accounting for more than 97% of the variance. This implies a high degree of correlation between the predicted and observed values.
• The findings illustrate that the principles of the ‘matching law’, a theory in behavioral psychology implying that individuals divide their time among multiple options so that the rewards from each option would be maximized, are also applicable to horses.