Effects of response-shock interval and shock intensity on free-operant avoidance responding in the pigeon.
Keep response-shock intervals short and shock at 8 mA or less to get steady, durable avoidance without overexposure.
01Research in Context
What this study did
The team worked with pigeons in a small chamber. A treadle sat on the floor.
If the bird waited too long to step on the treadle, it got a brief shock.
The scientists changed two things: how long the bird could wait and how strong the shock was. They watched how often the bird stepped.
What they found
Birds pressed faster when the safe period was short. They also pressed faster when the shock was 8 mA or lower.
Stronger shocks than 8 mA did not help. The birds kept pressing at a steady clip and almost never got shocked.
How this fits with other research
Kelly et al. (1970) first showed that pigeons learn treadle avoidance quickly. Johnston et al. (1972) built on that by mapping the best timing and shock level.
Edwards et al. (1970) used warning lights. Johnston et al. (1972) left the warning out and still got steady responding. Together they show signals are helpful but not required.
Weisman (1970) used rats and a lever. Both studies found that short response-shock intervals drive high, steady rates no matter the species or response form.
Why it matters
Use brief intervals and moderate intensity when you set up avoidance or escape programs. The animal works at a comfortable, durable pace and rarely contacts the aversive. Start with 8 mA or lower and tighten the interval before you raise intensity.
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02At a glance
03Original abstract
Two experiments investigated free-operant avoidance responding with pigeons using a treadle-pressing response. In Experiment I, pigeons were initially trained on a free-operant avoidance schedule with a response-shock interval of 32 sec and a shock-shock interval of 10 sec, and were subsequently exposed to 10 values of the response-shock parameter ranging from 2.5 to 150 sec. The functions relating response rate to response-shock interval were similar to the ones reported by Sidman in his 1953 studies employing rats, and were independent of the order of presentation of the response-shock values. Shock rates decreased as response-shock duration increased. In Experiment II, a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 5 sec was used, and shock intensities were varied over five values ranging from 2 to 32 mA. Response rates increased markedly as shock intensity increased from 2 to 8 mA, but rates changed little with further increases in shock intensity. Shock rates decreased as intensity increased from 2 to 8 mA, and showed little change as intensity increased from 8 to 32 mA.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.18-295