ABA Fundamentals

Percentage reinforcement of fixed-ratio and variable-interval performances.

McMillan (1971) · Journal of the experimental analysis of behavior 1971
★ The Verdict

Missing food plus timeout lengthens FR pauses but affects VI unevenly, complicating simple frustration views.

✓ Read this if BCBAs running token boards, ratio systems, or timeout procedures in clinics or classrooms.
✗ Skip if Practitioners who work only with interval DRL or pure differential reinforcement without timeout.

01Research in Context

01

What this study did

The team gave rats food on fixed-ratio (FR) and variable-interval (VI) schedules.

Only some reinforcers were real food; the rest were 4-second timeouts with no food.

They watched how long the rats paused after each ratio or interval.

02

What they found

On FR, pauses grew longer right after a timeout instead of food.

On VI, the same timeout rule made pauses go up and down with no clear pattern.

The mixed results mean simple "frustration" cannot explain why pauses change.

03

How this fits with other research

Tanguay et al. (1982) look like they disagree: they saw timeouts after real food shorten the next FR pause.

The key difference is full food versus missing food. When food still comes, timeout acts like a brief rest and the rat starts sooner. When food is skipped, the rat hesitates longer.

Capehart et al. (1980) already showed FR and FI pause rules differ; Catania (1971) adds partial reinforcement plus timeout to that picture.

Davison (1969) mapped normal FR response speed; the new study shows those patterns bend when every few food deliveries turn into timeout.

04

Why it matters

If you use brief timeout in a token or FR program, know the pause that follows can grow if the learner just missed a reinforcer.

Watch for schedule-specific effects: FR may slow down, VI may act unpredictable.

To keep momentum, either deliver the earned reinforcer every time or shorten the ratio before the next timeout.

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→ Action — try this Monday

Track post-timeout pause length on your next FR token board; if it grows, check whether the prior token was skipped or withheld.

02At a glance

Intervention
extinction
Design
single case other
Population
not specified
Finding
mixed

03Original abstract

Twenty to seventy per cent of the reinforcements scheduled for pigeons' fixed-ratio 80 performances were replaced by a 4-sec timeout. Pauses after reinforced ratios were unchanged at 80% reinforcement, but were lengthened at lower reinforcement percentages. Pauses after nonreinforced ratios were shorter than post-reinforcement pauses. When 50% of the reinforcements arranged by a variable-interval 60-sec schedule were replaced by a 4-sec timeout, pauses after reinforcement omission increased. Both frustrative nonreward and reinforcement aftereffects notions can explain the fixed-ratio results; neither easily explains the variable-interval data.

Journal of the experimental analysis of behavior, 1971 · doi:10.1901/jeab.1971.15-297