Maintenance of responding by squirrel monkeys under a concurrent shock-postponement, fixed-interval shock-presentation schedule.

Scientists worked with squirrel monkeys in a lab cage. The cage had two devices: a chain to pull and a lever to press.

First, monkeys learned to pull the chain. Each pull delayed a mild electric shock. This is called avoidance.

Next, the team added a lever. Now shocks arrived on a fixed timer whether the monkey pressed or not. The only way to postpone shock was still the chain. Yet the monkeys began to press the lever anyway, even though pressing never cancelled shock.

Lever pressing kept going even though it did not reduce shock. The monkeys’ own history of chain-pulling avoidance seemed to make the new response stick.

While the chain still controlled shock delay, the lever produced its own steady pattern of presses. Two separate response patterns ran side-by-side under the same shock schedule.

Berler et al. (1982) later saw the same outcome in rats. After shock, the animals kept pressing a bar even when the press did nothing to delay the next shock. The monkey and rat studies together show the effect is not species-specific.

Aragona et al. (1975) had already shown that monkeys can learn to tell apart ‘safe’ and ‘shock’ signals. The 1980 study moves that idea forward: it shows that past avoidance learning can spill over and maintain a brand-new response.

Gardner et al. (1977) found that pigeons kept pecking a key even when the shock schedule grew tougher. Bernal et al. (1980) echo this durability, but add the twist that the maintained response never actually cancelled shock.

For clinicians, the take-home is that a client’s old contingency history can keep unused or even useless responses alive. Before you try to replace a problem behavior, check whether it was once part of an avoidance chain. If it was, you may need to weaken the old contingency first, not just teach a new skill.