Effects of instructional constraints on human fixed-interval performance.

Kendrick et al. (1981) asked adults to work on a fixed-interval schedule. The timer paid a dime every 60 seconds, but only for the first response after the interval ended.

Half the group got one sentence: 'Try to finish the session quickly.' The other half heard: 'Try not to respond more than once per interval.' Same money, different words.

People told to 'finish quickly' paused less after each payoff and earned more dimes per minute. Their response bursts came sooner and lasted longer.

People told to 'limit responses' waited longer after each dime and earned less. The simple rule shaped the whole response pattern.

Saunders et al. (1988) repeated the idea with richer instructions. Adults who first practiced many FI values with varied rules later kept smooth, low-rate pausing. The 1981 and 1988 papers together show that both single and mixed verbal rules can bend FI performance.

Austin et al. (2015) twisted the FI clock by letting the participant's own press start each interval. That change also shortened pauses and blurred timing, extending the 1981 finding that small procedural tweaks have big effects.

FARMEMOORHEARSKELLEHER et al. (1964) added a DRL rule decades earlier: 'Wait at least 10 seconds between responses.' That extra contingency also stretched pauses and cut rate, proving that extra-schedule rules can sculpt FI patterns.

Your instructions are part of the contingency. If you want a client to pause less after reinforcement, frame the task around saving time, not counting responses. If you need longer pauses, do the opposite. State the rule in one plain sentence at the start; the schedule will do the rest.