Response-rate differences in variable-interval and variable-ratio schedules: An old problem revisited.
Response-rate gaps between VR and yoked VI schedules hinge on reinforced inter-response times more than on overall feedback functions.
01Research in Context
What this study did
Cole (1994) compared two reinforcement schedules head-to-head. One group earned rewards after a set number of responses. The other group earned rewards after a set amount of time.
The twist: the researchers made the time between rewards and the time between successful responses the same in both groups. They wanted to see which factor really drives how fast people respond.
What they found
Response rates landed in the middle. The time-based group responded faster than usual interval schedules, but slower than the ratio group.
Matching the time between successful responses barely changed the numbers. The link between response rate and reward timing mattered more.
How this fits with other research
Tanno et al. (2008) sharpened the picture. Using the same VR versus yoked VI setup, they showed that reinforced inter-response times alone explain the rate gap. They effectively superseded the dual-factor idea by isolating the key variable.
Guest et al. (2013) extended the finding. They added brief delays to rewards and saw big rate jumps only in the interval schedule. This confirms that schedule type, not just timing, shapes how delays affect behavior.
Gettinger (1993) set the stage the year before. His pigeon data first showed the classic pattern that Cole (1994) re-examined with tighter controls.
Why it matters
When you pick a schedule, know that two levers are in play: how often responses pay off and how those pays relate to response speed. If you want steady, moderate responding, lean on interval timing while watching reinforced IRTs. If you want faster bursts, ratio requirements still win. Check both factors when your client’s response rate shifts.
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02At a glance
03Original abstract
In Experiment 1, a variable-ratio 10 schedule became, successively, a variable-interval schedule with only the minimum interreinforcement intervals yoked to the variable ratio, or a variable-interval schedule with both interreinforcement intervals and reinforced interresponse times yoked to the variable ratio. Response rates in the variable-interval schedule with both interreinforcement interval and reinforced interresponse time yoking fell between the higher rates maintained by the variable-ratio schedule and the lower rates maintained by the variable-interval schedule with only interreinforcement interval yoking. In Experiment 2, a tandem variable-interval 15-s variable-ratio 5 schedule became a yoked tandem variable-ratio 5 variable-interval x-s schedule, and a tandem variable-interval 30-s variable-ratio 10 schedule became a yoked tandem variable-ratio 10 variable-interval x-s schedule. In the yoked tandem schedules, the minimum interreinforcement intervals in the variable-interval components were those that equated overall interreinforcement times in the two phases. Response rates did not decline in the yoked schedules even when the reinforced interresponse times became longer. Experiment 1 suggests that both reinforced interresponse times and response rate-reinforcement rate correlations determine response-rate differences in variable-ratio 10 and yoked variable-interval schedules in rats. Experiment 2 suggests a minimal role for the reinforced interresponse time in determining response rates on tandem variable-interval 30-s variable-ratio 10 and yoked tandem variable-ratio 10 variable-interval x-s schedules in rats.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.61-441