Punishment and rate of positive reinforcement.

Pigeons pecked a key for food on variable-interval schedules. Some birds got food every 30 seconds on average. Others waited 3 minutes.

The team then added a mild electric shock after every 100 pecks. They watched if the extra food slowed the punishment effect.

Shock cut responding by the same percent in both groups, about a large share. High-rate or low-rate baseline did not matter.

After shock ended, birds overshot their old rate for a few sessions. Mild shocks even gave short bursts of faster pecking during punishment.

McKearney (1970) later showed ratio schedules drop faster than interval schedules when shock grows, but both recover once shock stops. The 1968 study used only interval schedules, so the schedule type rule still holds.

Lea et al. (1977) found brain-stimulation reinforcement resists shock better than food. Their food birds matched the 1968 pattern, tying the rate-independence rule to reinforcer type.

Last et al. (1984) flipped the story: shock for long pauses sped birds up, not down. Timing of shock matters more than the grain size of food.

When you add a punisher, expect the same percent drop no matter how rich the reinforcement schedule is. Do not count on thicker reinforcement to cushion the blow. Watch for brief response bursts right after mild punishment and plan for rebound once the punisher stops. Use this rule to set realistic suppression targets and to explain temporary spikes to staff or parents.