Reinforcement of spaced responding in a simultaneous discrimination.
Under DRL, each stimulus keeps its own timer; changing one rule leaves the other untouched.
01Research in Context
What this study did
Two hungry pigeons pecked at two keys. One key lit up red, the other green. Each key had its own rule: wait at least 15 seconds between pecks on that key or no food.
The bird could switch keys any time. Researchers counted every peck to see if the wait rule on red changed how fast the bird pecked green, and vice-versa.
What they found
Each key kept its own pace. If the bird learned to wait 15 seconds on red, that did not slow or speed its pecks on green.
Responses to one stimulus never acted as 'mediators' for the other. The two DRL schedules lived in separate lanes.
How this fits with other research
Cicerone (1976) later showed pigeons can time even longer waits when the key color also tells them how long to wait. Byrd (1972) proved the basics: separate stimuli, separate control.
Flory et al. (1974) found blocking a bird's side-pecks with a harness broke the wait rhythm and sent rates up. Together the papers say: timing under DRL needs both stimulus control and freedom to use collateral moves.
Bensemann et al. (2015) saw DRO spill over and strengthen other untargeted moves in humans. DRL in pigeons stayed tidy—no spill-over—because each key had its own reinforcer line.
Why it matters
When you run two DRL programs at once—say, one for calling out and one for hand-flapping—treat them as independent. Change the timing rule on one? Do not expect the other to follow. Track each response separately and reinforce on its own clock.
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02At a glance
03Original abstract
Pigeons were exposed to three stimuli simultaneously with responses reinforced according to differential-reinforcement-of-low-rate schedules. Responses to one stimulus (the positive stimulus) that were spaced appropriately resulted in food presentation. The variables manipulated were the time parameter of the schedule (5, 10, 20, 30 sec) and the consequences of responding to the other two stimuli (the negative stimuli). The percentage of the total responses that occurred to each stimulus was independent of the schedule value but was dependent on the consequences of responding to the negative stimuli. If responses to both reset the schedule timer, responding was confined largely to the positive stimulus. If responses to neither had scheduled effects, the birds were more likely to respond to those stimuli. Responding to one negative stimulus could be selectively attenuated by having responses to that stimulus alone reset the timer. With the schedule time value held constant, the absolute rate of responding to the positive stimulus was either stable or decreased with maintained exposure; it did not change as a function of increases or decreases in responding to the negative stimuli. Rather than interacting and affecting each other, responses to the three stimuli were controlled independently by their relation to reinforcement. There was no evidence that responses to the negative stimuli mediated the spacing of responses to the positive stimulus.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.18-443