Responding maintained under fixed-interval and fixed-time schedules of electric shock presentation.
Shock postponement under fixed-interval schedules can reinforce responding, proving contingency matters more than the aversive nature of the consequence.
01Research in Context
What this study did
Greene et al. (1978) compared two shock schedules. In one, a lever press postponed the next shock for a fixed time. In the other, shocks came at fixed times no matter what the animal did.
They recorded how often the animals pressed under each rule.
What they found
Animals pressed more when the lever postponed shock. The pattern was a pause, then faster pressing as shock time neared.
Fixed-time shocks produced little pressing. The result shows shock can maintain behavior if it is response-dependent.
How this fits with other research
Byrd (1972) saw the same pause-run pattern under fixed-interval shock years earlier. F et al. added the fixed-time control to prove the pattern is truly operant.
Bacotti (1978) ran a similar test with variable-interval shock and got the same lift from response-dependent delivery. Together the papers show the rule holds across interval types.
Last et al. (1984) extended the idea. They timed shock to punish long pauses between responses. That shock also kept the behavior going, showing contiguity matters even within a schedule.
Appel (1968) looks opposite at first glance. He found fixed-interval shock suppressed pressing. The difference is contingency: B used shock to punish every press, while F used shock postponement to reinforce pressing. Same schedule, opposite roles.
Why it matters
The study reminds you that contingency, not just the consequence, drives behavior. A timeout, a brief break, or even a mild aversive can strengthen responding if the person controls its timing. Check your programs: if you deliver "sensory breaks" or "warnings" on a clock, you may accidentally weaken the very responses you want. Make the break depend on the target act and you will see the rate rise.
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02At a glance
03Original abstract
Following initial histories under a schedule of electric shock postponement, lever pressing in squirrel monkeys was maintained under fixed-interval and fixed-time schedules of electric shock presentation. No difference in either rate or pattern of responding was obtained when these schedules were presented as components of a multiple schedule. When they were presented singly for long periods of time, the fixed-interval schedule consistently maintained a higher response rate than the fixed-time schedule. The pattern of responding under both schedules was similar, typically consisting of a pause at the beginning of each interval followed by either a steady or a positively accelerating rate of responding. The results suggest that the response-shock dependency is of critical importance in the maintenance of high rates of responding under schedules of electric shock presentation, and support the general view that such responding may be conceptualized as operant behavior under control of many of the same variables that control responding under comparable schedules of food or water reinforcement.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.30-271