CONDITIONED SUPPRESSION IN GOLDFISH AS A FUNCTION OF SHOCK-REINFORCEMENT SCHEDULE.

Goldfish pressed a lever for food. Sometimes the lever also gave a mild electric shock. The fish got shocks on every press in one phase, then only half the presses in another phase. The team later stopped all shocks to see how fast lever pressing bounced back.

This 1964 lab study used a single-subject design. The question was simple: does partial shock pairing make the fear response weaker later?

Fish that had shocks on only 50 % of presses lost their fear faster. When shocks ended, these fish returned to steady lever pressing sooner than fish that had been shocked every time.

In plain words, partial bad news made the bad news easier to forget.

DARDANO et al. (1964) ran a similar test with pigeons working for food. They put the shock inside the work chain, not after it. Birds paused longer after food when shock strength went up, showing the same core idea: aversive events can target different parts of a response chain.

Hineline (1970) moved the goalpost. He showed that a lever press could keep its strength if it only delayed, but did not remove, upcoming shocks. Together these papers map two levers of control: how often the shock happens and when it happens.

Jones (1969) adds a twist. He used shocks that did not care about lever pressing. Avoidance responding still lived on even when most shocks were unavoidable. The 1964 study and T’s work sit side-by-side: one cuts fear by thinning shock probability, the other shows fear can persist when shock is random.

Thinning aversive consequences can speed recovery from fear-based avoidance. If you use response cost or mild reprimands, try delivering them on a lean schedule once the skill is stable. The learner drops the fear response faster, letting you return to pure reinforcement sooner.