The role of discriminative stimuli in concurrent performances.

The team ran two pigeons on two side-by-side keys. Each key paid off on its own schedule, but the birds could hop between them. In one setup, the keys changed color when a different schedule was active. In the other setup, the colors never changed. The researchers recorded every peck and the time spent on each key.

They wanted to know if the color cues made the birds' choices line up with the payoff rates.

When the colors switched with the schedules, the birds' pecks and time matched the grain payoff ratios almost perfectly. Without the color cues, the match was loose and wandered. The birds still got grain, but their behavior no longer tracked the odds.

Clear cues tied to each schedule were needed for strict matching.

Smith et al. (1975) showed that even the number of responses a pigeon makes can act as its own cue. G et al. extend that idea: external cues are what keep choice tidy across two schedules.

Iwata (1988) and Clark et al. (1977) also used single-case designs to test what controls behavior. All four studies agree that stimulus conditions, not extra words or prior training, drive the outcome.

Together they build a chain: first, responses can cue themselves; next, outside cues sharpen choice; finally, stripping extra steps keeps interventions lean.

If you run concurrent schedules in a classroom or clinic, add a clear stimulus for each option. A green card for math and a blue card for reading, for example. Without those signals, clients may not distribute their time the way the reinforcement rates suggest they should. One simple cue can tighten matching and make your data cleaner.