The discriminative control of free-operant avoidance despite exposure to shock during the stimulus correlated with nonreinforcement.
Stimuli that signal fewer bad events can lock in avoidance even when the ‘safe’ cue still delivers pain.
01Research in Context
What this study did
The team set up a free-operant avoidance box. A light and a dark period alternated.
During light, every bar press delayed shock for 20 s. During dark, shocks came no matter what the animal did.
They asked: will the animal still learn to press mostly in the light when the dark keeps hurting?
What they found
The animals pressed almost only when the light was on. The dark got more shocks, yet the light stayed in charge.
The result shows shock-frequency drop, not total pain removal, can drive and keep avoidance.
How this fits with other research
Shimp et al. (1974) first showed pigeons peck just to cut shock rate. Aragona et al. (1975) added the light/dark cue, proving the same rule works under clear stimuli.
Gardner et al. (1977) later tweaked shock delay and size. Responding held steady, backing the idea that fewer shocks, not easier shocks, keeps behavior alive.
Dardano (1970) looked like a clash: extra shocks that the animal cannot escape cut pressing. The key difference is contingency. In Aragona et al. (1975) the light still gives control; in Dardano (1970) the new shocks are truly random, so control disappears and responding drops.
Why it matters
Your clients may keep safety behaviors even when some danger remains. Think of a child who keeps checking traffic lights even after rare near-misses. The study says the cue, not perfect safety, can lock the behavior in place. When you fade avoidance, first dilute the cue’s link to relief, not just the rate of aversive events.
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02At a glance
03Original abstract
Four rats were trained in darkness on a free-operant avoidance procedure in which shocks occurred randomly, but lever presses could reduce their frequency. Discrimination training followed, during which responses in light continued to reduce shock frequency, but responses in darkness had no effect. During each cycle, the light period was 4 min, while darkness lasted only until a 20-sec interval had elapsed without a response. This no-response requirement was increased to 40 sec for three animals and eventually to 60 sec for two of them. Discriminative control developed, despite a greater shock density in the dark, with response rate and number of responses per shock maintained or increasing during light and decreasing to very low values in darkness. Two animals were later exposed to a procedure in which shock density was unaffected by responding either in light or darkness. A 60-sec no-response requirement was continued in the dark. Discriminative control persisted through 42 sessions for one animal and required 45 sessions to approach extinction for the other animal. The role of the light as a potential conditioned reinforcer of other behavior in the dark was implicated in the development and persistence of discriminative control. These data support shock-frequency reduction as reinforcement for avoidance behavior.
Journal of the experimental analysis of behavior, 1975 · doi:10.1901/jeab.1975.23-111