Reinforcement contingencies maintaining collateral responding under a DRL schedule.
Collateral behavior survives in DRL only when it produces a signal or is required; accidental food pairings are not enough.
01Research in Context
What this study did
The team used a two-key DRL 20-second schedule with rats.
Animals had to wait 20 s between presses on the main lever to earn food.
A second key was available. The experimenters changed what this extra key did across phases.
Sometimes the extra key gave a light, sometimes it had to be pecked to finish the food cycle, and sometimes it did nothing.
What they found
Extra-key pecks only kept happening when they turned on a light or were required for food.
When the extra key had no clear job, rats soon stopped touching it.
Accidental pairings with food were not enough to keep the collateral behavior alive.
How this fits with other research
MOLLIVER (1963) showed that adding a mediating lever with its own light sharpens DRL timing. The 1969 study digs deeper: the light or the requirement is the real glue, not lucky food pairings.
Schwartz et al. (1971) later repeated the idea with pigeons. A spare key that merely glowed lifted accurate spaced responding from below 10 % to 75 %. Again, a visible stimulus did the work, not accident.
Rey et al. (2020) looked at long DRO schedules and also found that accidental reinforcement gives only a tiny, brief bump. All three papers agree: explicit contingencies or clear signals maintain collateral behavior; mere coincidence does not.
Why it matters
When you use DRL or DRO to slow problem behavior, give the client something clear to do.
A button that lights up, a counter that beeps, or a required step before the reinforcer will keep the mediating response strong.
Skip the hope that accidental reinforcement will do the job—it won’t.
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02At a glance
03Original abstract
Two-key conjunctive schedules were studied with one key (food key) under a differential-reinforcement-of-low-rate 20-sec schedule, while the consequences of responding on another key (collateral key) were varied. When food depended not only upon a food-key interresponse time in excess of 20 sec, but also upon the occurrence of one or more collateral-key responses during the food-key interresponse time, the rate of collateral-key responding was low and food-key interresponse times rarely exceeded 20 sec. When collateral-key responses could produce a discriminative stimulus correlated with the availability of food under the DRL schedule, the discriminative stimulus functioned as a conditioned reinforcer to maintain higher rates of collateral-key responding, and the spacing of food-key responses increased. If the occurrence of the discriminative stimulus was independent of collateral-key responses, the rate of collateral-key responding was again low, but the spacing of food-key responses was still controlled by the discriminative stimulus. Both the conditioned reinforcer and the explicit reinforcement contingency could maintain collateral-key responding, but the adventitious correlation between collateral-key responses and the delivery of food could not maintain very much collateral-key responding. The pattern of responding on the food-key was determined to a much greater extent by the correlation between the discriminative stimulus and the delivery of food than by the pattern of responding on the collateral key.
Journal of the experimental analysis of behavior, 1969 · doi:10.1901/jeab.1969.12-413