Enhancement of conditioned autonomic responses in monkey when preshock signals occasion operant suppression.

One monkey sat in a chair. A red light came on. Two seconds later the monkey got a mild shock. The red-shock pair happened many times. This is classical conditioning.

Sometimes the monkey could reach food. Other times the chair blocked the food. Blocking food is called operant suppression. The team measured heart rate changes during both setups.

When food was blocked, the monkey’s heart jumped higher and faster after the red light. The same shock now produced a stronger body reaction.

During free feeding, the heart still rose, but not as much. Suppressing one response made another response grow.

Terrace (1969) showed monkeys can learn to pull a lever to avoid shock. That study shaped a new escape response. Byrd (1980) keeps the same species and shock, but shows stopping one action can boost a different, automatic response.

Kuroda et al. (2019) found electric shock punished zebrafish swimming. Here, shock plus suppression does the opposite: it amplifies the monkey’s conditioned heart jump. The difference is species and task, not the shock itself.

Michael (1974) used food omission to cut pigeon key-pecking. Food omission and operant suppression both remove access to reinforcers. Both procedures can change the strength of other behaviors that are still in place.

If you withhold a reinforcer to reduce problem behavior, watch for side effects. A client’s automatic reactions—heart rate, breathing, skin temperature—may spike. Pair your suppression plan with relaxation training or respondent extinction to keep the body calm while the target behavior drops.