Reinforcement contingencies as discriminative stimuli.

Pigeons pecked a matching-to-sample task. After each trial the birds entered either a DRL or a DRO schedule.

The just-finished schedule—not a colored light—told the bird which comparison key would pay off next. Researchers then reversed these schedule-to-key rules to test stimulus control.

The pigeons scored 80-100% correct when the rule was: “If you just did DRL, pick left; if you just did DRO, pick right.”

When the researchers flipped the rule, accuracy flipped too. The contingency itself had become the cue.

Crowley (1979) ran the same DRL/DRO cue setup and added random probe trials. The replication held: contingency identity still drove choices, showing the effect is sturdy.

Davis et al. (1994) moved the cue in time. They put a brief light right after the choice, not after the whole schedule. Learning sped up only when that light came immediately, extending the 1975 finding by showing timing matters as much as presence.

Clark et al. (1970) looks like a contradiction: flashing an orange light after wrong matches hurt accuracy. The difference is cue meaning: their light was paired with food, so it worked as a reinforcer for wrong picks. In 1975 the cue was the schedule itself, not an added reinforcer, so it guided rather than warped choices.

You can turn the recent learning history into a prompt. After a child finishes a DRL spelling task, tell them, “You just waited three seconds—now it’s quick-answer time,” and switch to a DRO social question. The child’s own past contingency becomes the signal for what to do next, no extra tokens or lights needed.