Reduction of shock duration as negative reinforcement in free-operant avoidance.

Eight lab rats lived in a cage with a lever. If they pressed the lever fast enough, any shock they got lasted only 0.3 seconds. If they waited too long, the same shock lasted 3 seconds.

The team counted how fast the rats pressed once the short-shock rule began. No food, no sound, no shock removal—just shorter pain.

Six rats quickly learned to press like crazy. They kept the pace high for the whole session. Short shocks alone kept the lever going.

Two rats took longer, but they also sped up. Cutting duration, not intensity or number, was enough to drive avoidance.

Hamm et al. (1978) ran the same cage set-up but cut shock strength instead of length. Both studies show rats work hard when any single aversive feature drops. The 1980 paper extends that idea to duration.

Taras et al. (1993) review says “faster to the good stuff” is a built-in reinforcer. Shorter shock = faster return to safety, so the lever press fits the delay-reduction rule.

Schmidt et al. (1969) found that once avoidance starts, shocks can keep the bar moving even if they no longer depend on the rat’s timing. The 1980 study adds a new twist: the contingency can hinge on how long, not if, the shock happens.

Your client’s escape or avoidance may be fed by tiny cuts in aversive time, not just by skipping the event. Think dental drill: shorter buzz per contact could reinforce “hold still” better than promises of no drill at all. Try shaving task duration, not only task difficulty, when you fade demands.