The puzzle of responding maintained by response-contingent shock.
Shock can keep behavior going without acting as a reinforcer—schedule spacing makes the difference.
01Research in Context
What this study did
The team set up a fixed-interval schedule where every response produced a brief electric shock. They added a tandem spacing rule: shocks only occurred if a set time had passed since the last shock.
Lab animals worked under these conditions. The researchers tracked how response speed and pattern changed across the session.
What they found
Response rates moved in the opposite direction from what positive reinforcement would predict. Animals slowed down when faster responding should have earned more shocks.
The pattern looked like avoidance, not reward. The authors say shock was controlling behavior through aversive escape, not by acting as a reinforcer.
How this fits with other research
Zimmerman (1969) used the same shock-plus-fixed-interval setup but called the results positive reinforcement. The difference: W saw faster responding near the end of each interval, while T et al. saw the reverse. Both labs ran single-case designs, so the clash is real.
Rachlin (1972) showed animals adjust their rate to keep shock intensity steady under titration. T et al. extend that idea: even with fixed shock level, animals still tune their timing to minimize exposure.
Koegel et al. (1992) proved punishment works at the micro level—specific inter-response times drop when paired with shock. T et al. flip the lens: the same micro-contingencies can maintain, not suppress, behavior when the schedule spacing changes.
Why it matters
When you see behavior persisting despite apparent punishment, check the local contingency before calling it reinforcement. A tiny schedule tweak—like a tandem gap—can turn shock from a punisher into a maintenance cue. Probe response-shock timing in your functional analysis; you may find avoidance where you thought reward was at work.
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Join Free →Graph inter-response times during your punishment procedure; if long pauses collect right before the consequence, you may be seeing aversive maintenance, not failed punishment.
02At a glance
03Original abstract
Four squirrel monkeys were first exposed to a sequence of procedures that reliably generate responding maintained by brief response-contingent electric shocks arranged according to a fixed-interval schedule. After responding had become stable on the fixed-interval schedule, additional contingencies were added in tandem, whereby after completion of the interval, the spacing of responses affected shock delivery. In one procedure, responses had to be spaced more widely than their previous median value if shock were to be delivered. In the other procedure, responses had to be spaced more closely to produce shock. On the first of these procedures, decreased but stable responses rates would indicate that shock functioned as a positive reinforcer; on the second, increased response rates would indicate the positively reinforcing function. Instead, response rates accelerated on the procedure that targeted more widely spaced responses for shock delivery, and decelerated or ceased on the procedure that arranged for shocks to be produced by more closely spaced responses. Consistent with other recent findings, these results question the interpretation of performances maintained by response-contingent shock as engendered by positive reinforcement and are consistent with aversive-control interpretations. The details of that aversive control are not entirely clear, however, and these same procedures would be informative if applied to shock-maintained behavior that is generated in other ways.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.61-135