Clock-delivered reinforcers in conjunctive and interlocking schedules.

Rats pressed a lever for food. A clock ticked every few seconds.

The clock set the rules. In one setup the rat had to press after the clock ticked AND meet a normal VI schedule. This was the conjunctive group.

In the other setup the clock tick moved the VI schedule ahead faster when the rat pressed quickly. This was the interlocking group. The study watched how fast and how steadily each group pressed.

Conjunctive rats slowed down. They paused after each food, then pressed in quick bursts.

Interlocking rats sped up. They kept a smooth, fast pace without long breaks.

Same clock, same food, but the rule change flipped both rate and pattern.

Kuroda et al. (2018) later showed that the overall correlation between pressing and getting food—not just the timing—can drive behavior. Appel (1968) is an early demo: the conjunctive rule weakens that correlation, so rats press less.

Hursh et al. (1974) ran the same kinds of schedules with three rats pressing together. Groups paused less and pressed faster than the single rats in Appel (1968). The pattern stayed, but the numbers shifted, showing the rule works across unit sizes.

Byrd (1972) and Cicerone (1976) used DRL schedules that also force time between presses. They found separate stimulus control for long waits, matching B’s pause-and-run bursts. Together they tell us temporal rules carve up responding into chunks we can see and count.

If you want steady high-rate work, use an interlocking rule: let time advance faster when the client responds quickly. If you want the client to pause and then work in focused bouts, add a conjunctive clock requirement. Check the overall response–reinforcer correlation with a simple scatter plot; Kuroda et al. (2018) show this matters as much as the schedule name.