Competitive fixed-interval performance in humans.
A single competitive FI session turns smooth human scallops into rapid break-and-run bursts that stick even when competition ends.
01Research in Context
What this study did
The team asked 12 college students to press a button for money. They used a fixed-interval (FI) schedule: the first press after 30 seconds paid 5 cents.
To make it competitive, only the fastest person in a pair got the money. Students sat side-by-side and could see each other's lights.
What they found
Competition doubled response rates. Students stopped pressing right after payoff, then burst at the end of the interval — the classic 'break-and-run' pattern.
The pattern stuck even when students later worked alone. One session of rivalry left a lasting mark on timing.
How this fits with other research
Duncan et al. (1972) showed pigeons on multiple FIs match rate to payoff. Timberlake et al. (1987) move the same schedule into humans and add one twist: a rival. The birds never competed, so the jump from animal lab to human lab is clean.
Tracey et al. (1974) also paid adults on FI, but for neat handwriting. They saw smooth scallops, not break-and-run. The difference is social: handwriting was solo; button pressing here was a race. Same schedule, new contingency, new shape.
Borrero et al. (2005) later peeked inside the brain during human FI tasks. They found frontal-striatal spikes when money cues appeared. The 1987 paper gives the behavioral base that the imaging study builds on.
Why it matters
If you run FI token boards or payday drills, know that peer competition can flip the response curve from scallop to burst. Use this when you want quick acceleration — like speed drills or fluency checks. Skip it when you want steady, calm rates. One rival minute can reshape timing for the rest of the day.
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Join Free →Pair students for a 2-minute 'beat the clock' FI game; watch if the faster burst carries over to solo work.
02At a glance
03Original abstract
Two persons responded in the same session in separate cubicles, but under a single schedule of reinforcement. Each time reinforcement was programmed, only the first response to occur, that is, the response of only one of the subjects, was reinforced. "Competitive" behavior that developed under these conditions was examined in three experiments. In Experiment 1 subjects responded under fixed-interval (FI) 30-s, 60-s, and 90-s schedules of reinforcement. Under the competition condition, relative to baseline conditions, the response rates were higher and the pattern was "break-and-run." In Experiment 2, subjects were exposed first to a conventional FI schedule and then to an FI competition schedule. Next, they were trained to respond under either a differential-reinforcement-of-low-rate (DRL) or fixed-ratio (FR) schedule, and finally, the initial FI competition condition was reinstated. In this second exposure to the FI competition procedure, DRL subjects responded at lower rates than were emitted during the initial exposure to that condition and FR subjects responded at higher rates. For all subjects, however, responding gradually returned to the break-and-run pattern that had occurred during the first FI competition condition. Experiment 3 assessed potential variables contributing to the effects of the competitive FI contingencies during Experiments 1 and 2. Subjects were exposed to FI schedules where (a) probability of reinforcement at completion of each fixed interval was varied, or (b) a limited hold was in effect for reinforcement. Only under the limited hold was responding similar to that observed in previous experiments.
Journal of the experimental analysis of behavior, 1987 · doi:10.1901/jeab.1987.47-145