Preference for less frequent shock under fixed-interval schedules of electric-shock presentation.

Duker et al. (1991) let two monkeys pick between two levers. One lever gave a mild shock every six minutes. The other gave the same shock every two minutes. The monkeys could switch any time. The team watched which lever each animal stayed on longer.

The shocks were equal in strength. Only the timing changed. The question was simple: would the animals prefer less-frequent pain?

Both monkeys quickly chose the six-minute schedule. They stayed there session after session. Even though the shock itself was identical, they picked the slower rhythm. The longer gap felt better.

The choice was stable. It did not fade as the study went on. The animals acted like “fewer shocks” was a reinforcer.

Aragona et al. (1975) ran a similar choice test with rats. Those animals picked signaled shock over unsignaled shock when intensity rose. Both studies show that aversive events follow the same choice rules as food or water: timing and signals matter.

WALLETHOMAS et al. (1963) added a clock stimulus to an FI schedule and saw monkey responding drop to almost zero. That looks like the opposite of the new finding, but the difference is the lever. In 1963 the clock was forced; in 1991 the monkey could walk away. Choice, not the clock, drove the result.

Blanchard et al. (1979) later showed that a two-second warning signal makes signaled shock strongly preferred. Together the three papers tell one story: animals do not just hate shock; they hate uncertainty and high rates. Give them control and they will pick the calmer option.

Your clients may pick slower schedules of aversive events if they can control the pace. When you must use restraint, timeout, or correction, offer a choice and stretch the time. The same principle works for non-aversive tasks: longer breaks between demands can make the work itself more acceptable. Let the learner choose the “six-minute lever” whenever safety allows.