Shock intensity and signaled avoidance responding.
Once a minimum shock level sustains avoidance, higher intensities do not improve behavior and can disrupt it.
01Research in Context
What this study did
The team worked with rats in a signaled avoidance task. A tone warned that shock was coming unless the rat pressed a lever.
They tested five shock levels from mild to strong. Each rat stayed at one level for many sessions.
The goal was simple: find the lowest shock that kept avoidance going and see if stronger shocks helped more.
What they found
Every rat had a clear cutoff. Below that shock level, avoidance fell apart. Above it, stronger shocks gave no extra boost.
In fact, the highest shocks sometimes broke the pattern. Rats paused or acted oddly even though the warning tone still worked the same.
The tone stayed in charge no matter the shock strength. Stimulus control did not improve with more pain.
How this fits with other research
Hamilton et al. (1978) saw a brief dip then surge in avoidance when foot shock was signaled. Mosk et al. (1984) show that once the shock is strong enough, extra intensity does not drive more of that surge. The two studies line up: the signal matters more than the pain level after the minimum is met.
WALLETHOMAS et al. (1963) titrated shock in monkeys and humans and found finer steps let subjects handle more pain. Mosk et al. (1984) add that in rats, once the minimum is found, bigger jumps do not help and can hurt. Together they say: find the least aversive level that works, then stop.
Davis et al. (1972) showed that pairing tone with light raised avoidance rates. Mosk et al. (1984) show that simply cranking up shock does not. The lesson: enrich the signal, not the aversive, to strengthen behavior.
Why it matters
When you use escape or avoidance procedures, start low and raise intensity only until the learner responds reliably. Going past that point wastes effort and risks side effects. Test each client’s threshold, lock it in, and focus on clear, consistent signals instead of stronger aversives.
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02At a glance
03Original abstract
Five rats were submitted to a signaled free-operant avoidance contingency. Throughout the experiment, shock intensity was varied from 0.1 to 8.0 mA, with shock duration constant at 200 milleseconds. Results indicate: (a) an all-or-none effect of shock intensity on response and shock rates, on percentage of shocks avoided, and on frequency of occurrence of responding during the preshock stimulus; and (b) no systematic effect of shock intensity on stimulus control, measured either by the percentage of stimulus presentations accompanied by a response or by the percentage of responses that occurred during those preshock stimuli. Such results indicate that for each subject there is a minimum shock intensity necessary to establish and maintain avoidance responding; intensities higher than this minimum value have little or no effect on responding (with an upper limit for those strong intensities with a general disruptive effect on behavior).
Journal of the experimental analysis of behavior, 1984 · doi:10.1901/jeab.1984.42-67