Response-dependent shock in second-order fixed-ratio schedules of food presentation.

Weisman et al. (1975) worked with pigeons on a second-order schedule. The birds had to finish 50 pecks to get food, but only every ninth food cycle ended with a brief shock.

They slowly made the shock come more often—every ninth, then every third, then every cycle—while counting how fast the birds pecked.

More frequent shock made the pigeons peck less. The birds also paused after food, then pecked in quick bursts.

Even rare shock—only one in nine cycles—still cut response rates, showing punishment can work when it feels unpredictable.

Bacotti (1978) extends this idea. They mixed contingent and non-contingent shocks and found contingency itself matters. Birds slowed most when the shock was tied to their peck, even if total shocks stayed the same.

Sailor (1971) and McKearney (1970) are earlier stepping-stones. They showed higher voltage or denser shock drops ratio responding faster than interval responding, foreshadowing the dose effect G et al. mapped inside second-order FR.

Byrd (1972) looks like a contradiction—monkeys kept pressing when shock was the only scheduled event—but the monkey study used shock as a reinforcer, not a punisher. Same schedule, opposite function, so both papers can be true.

For BCBAs, the study is a reminder that even thin, response-linked aversives can suppress behavior. If you use punishment procedures—time-out, brief restraint, or token fines—spacing them out will not necessarily spare the learner. Instead, tie reductions in the aversive to clear, safe alternative responses and track whether the behavior returns in bursts.