The effect of response force on avoidance rate.

Two adults earned money by saying a word loud enough to avoid shocks. The word had to hit 80 decibels at first. Later the rule jumped to 110 decibels. The team counted how many avoidance words the adults said under each loudness rule.

This is a classic single-case lab test. It asks whether harder work kills avoidance the same way it kills food-reinforced behavior.

When the shout had to be louder, both adults spoke less. Their above-threshold responses dropped. Their total avoidance responses also dropped. Harder vocal work meant less safety talk.

Anonymous (1995) and Lowe et al. (1995) show the same drop in rats pressing a stiff lever for food. The force-rate link now spans species, schedules, and reinforcer types.

Llewellyn et al. (1976) looks like a contradiction. They raised force on a variable-interval food schedule and kept overall response rate steady. The difference is the schedule. Avoidance lets you escape future pain, so extra effort feels like double trouble. VI food gives steady payoff, so animals adjust and keep pressing.

CHUNG (1965) set the stage. That study first mapped how rate falls once force crosses a threshold. Walker (1968) confirms the rule holds even when the response is vocal and the reinforcer is shock avoidance.

If you ask a client to work harder for the same payoff, expect less behavior. This is true for escape tasks like hand-raising to skip a demand or vocal scripts to avoid sensory input. Lower the effort or raise the payoff to keep the skill alive.