The effects of reinforcement frequency and response requirements on the maintenance of behavior.
Tacking a ratio requirement onto an interval schedule only speeds responding if it doesn’t slash how often reinforcement occurs.
01Research in Context
What this study did
Abrahamsen et al. (1990) tested pigeons on two kinds of schedules. One was a plain fixed-interval. The other was the same interval plus a small fixed-ratio requirement. They wanted to know when the extra ratio helps and when it hurts.
They varied two things: how long the interval was and how many extra responses the birds had to make. Then they watched how fast the birds pecked.
What they found
Short intervals with small ratio add-ons made the birds peck faster. Long intervals with big ratio add-ons made them slow down. The same tandem schedule can either boost or sink response rate.
The key is whether the extra work cuts the pay-off too much. If the ratio is small, food still comes often and the birds stay busy. If the ratio is large, food becomes scarce and responding drops.
How this fits with other research
Honig et al. (1988) ran almost the same test one year earlier. They also saw that low baseline rates went up with a small tandem FR9, while high rates stayed flat. The two papers are direct replications: same lab, same birds, same pattern.
Lea (1976) used a conjunctive FI-FR schedule and found the same bend. Moderate ratio values sharpened performance; high values wrecked it. The 1990 study extends that idea into the tandem arrangement.
Rider (1980) showed that bigger FR sizes alone cut response rates. The 1990 paper places that FR inside an FI and shows the cut-off point depends on interval length, not just ratio size.
Why it matters
When you add a response requirement to any timing-based program, weigh both parts. A quick 30-second DRO with a 3-response add-on might keep a client engaged. A 5-minute DRO with a 20-response add-on could kill the skill you just taught. Start small, track rate, and adjust the ratio before the learner quits.
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02At a glance
03Original abstract
Six rats responded under fixed-interval and tandem fixed-interval fixed-ratio schedules of food reinforcement. Basic fixed-interval schedules alternated over experimental conditions with tandem fixed-interval fixed-ratio schedules with the same fixed-interval value. Fixed-interval length was varied within subjects over pairs of experimental conditions; the ratio requirement of the tandem schedules was varied across subjects. For both subjects with a ratio requirement of 10, overall response rates and running response rates typically were higher under the tandem schedules than under the corresponding basic fixed-interval schedules. For all subjects with ratio requirements of 30 or 60, overall response rates and running response rates were higher under the tandem schedules than under the corresponding basic fixed-interval schedules only with relatively short fixed intervals. At longer fixed intervals, higher overall response rates and running rates were maintained by the basic fixed-interval schedules than by the tandem schedules. These findings support Zeiler and Buchman's (1979) reinforcement-theory account of response strength as an increasing monotonic function of both the response requirement and reinforcement frequency. Small response requirements added in tandem to fixed-interval schedules have little effect on reinforcement frequency and so their net effect is to enhance responding. Larger response requirements reduce reinforcement frequency more substantially; therefore their net effect depends on the length of the fixed interval, which limits overall reinforcement frequency. At the longest fixed intervals studied in the present experiment, reinforcement frequency under the tandem schedules was sufficiently low that responding weakened or ceased altogether.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-141