Clock control of human performance on avoidance and fixed-interval schedules.

Four adults sat at a desk with two buttons. Pressing the right button on time gave them money.

A wall clock ticked off the seconds. The scientists added a second hand that turned red when payoff time was near.

They compared how the adults acted with and without the red clock hand on two schedules: avoidance (press to stop a buzzer) and fixed-interval (press after a set time).

With the red hand, people pressed less but still earned the same amount of money.

The drop was biggest on the avoidance schedule. Response rate fell by almost half while the buzzer stayed quiet.

On fixed-interval, the red hand also cut extra presses, but the change was smaller.

Smith et al. (2023) later showed the same idea works in differential reinforcement. They cycled reinforcement on and off and saw resurgence drop, just like the clock cut extra presses here.

SHETTLEWORTCHARNEY et al. (1965) proved schedule control works no matter what the reinforcer is. The 1976 study adds that a simple visual cue can fine-tune that control.

Catania et al. (1972) saw accuracy dip mid-interval on fixed schedules. The clock hand gives a fix: it tells the learner when the dip is ending, so they don’t guess.

You can add a cheap visual timer to any avoidance or interval program. The learner does less work, but reinforcement stays the same. Try a color-changing clock, a fading light, or even a progress bar on a tablet. Less effort, same gain.