Avoidance based on shock intensity reduction with no change in shock probability.
Avoidance can be fueled only by making the bad thing less bad, not less likely.
01Research in Context
What this study did
Scientists put rats in a box with a lever. If the rat waited too long between presses, it got a strong shock.
Pressing faster kept the shocks weak. Shock chance stayed the same—only the strength changed.
What they found
The rats learned to press quickly to keep pain low. When the time limit shrank, they pressed even faster.
Avoidance worked even though shocks still happened on every cycle.
How this fits with other research
Two years later Rosenthal et al. (1980) swapped intensity for duration. Rats still worked hard to get shorter shocks. Together the pair shows any shock feature can drive avoidance.
Earlier work by Malagodi et al. (1975) used a warning light before each shock. They found long, mixed wait times sped learning. The 1978 study removed the signal and still got fast lever pressing—proof the reduction itself is enough.
Schmidt et al. (1969) showed responding can linger after shocks stop being tied to the lever. The 1978 data add that the lever can be kept alive simply by making each shock milder.
Why it matters
Your client’s escape or avoidance may be kept going by tiny drops in effort, noise, or discomfort—not by full removal. Look for ways they already shrink the aversive event and reinforce those mini-reductions to build useful replacement responses.
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02At a glance
03Original abstract
Rats were trained on a free-operant avoidance procedure in which shock intensity was controlled by interresponse time. Shocks were random at a density of about 10 shocks per minute. Shock probability was response independent. As long as interresponse times remained less than the limit in effect, any shocks received were at the lower of two intensities (0.75 mA). Whenever interresponse times exceeded the limit, any shocks received were at the higher intensity (1.6 mA). The initial limit of 15 seconds was decreased in 3-second steps to either 6 or 3 seconds. All animals lever pressed to avoid higher intensity shock. As the interresponse time limit was reduced, the response rate during the lower intensity shock and the proportion of brief interresponse times increased. Substantial warmup effects were evident, particularly at the shorter interresponse-time limits. Shock intensity reduction without change in shock probability was effective in the acquisition and maintenance of avoidance responding, as well as in differentiation of interresponse times. This research suggests limitations on the generality of a safety signal interpretation of avoidance conditioning.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.30-293