Short-term remembering of discriminative stimuli in pigeons.

Bernal et al. (1980) tested how pigeons remember colors when they must wait before choosing. Birds saw a color sample, then waited 0–10 seconds before picking the matching key.

During the wait the team either cut off feeder access or let the birds peck a blank key. They wanted to know if these small changes would help or hurt memory.

Longer waits always hurt accuracy. Feeder interruptions made the drop steeper. Letting the birds peck during the wait slowed the drop.

In plain words: giving the birds something to do protected their memory.

Rider et al. (1984) and Burgio et al. (1986) saw the same hyperbolic decay in pigeons, so the basic drop is reliable. Madden et al. (2003) added that even delayed food can steepen forgetting, extending the 1980 point that timing matters at every step.

Davis et al. (1994) seems to disagree: immediate flashes after correct choices sped learning, while E et al. found any interruption hurt. The flash was instant and signaled "correct," but the feeder cut was delayed and meaningless. Timing and meaning, not just presence of a stimulus, decide whether it helps or harms.

Clark et al. (1970) had already shown that a simple orange flash could wreck accuracy if it acted like a reinforcer. Together these papers warn that any stimulus during the gap must be planned with care.

When you run delayed matching with learners who have autism or ADHD, build in a simple mediator: let them quietly name the sample, point to a blank card, or tap a fidget. These tiny responses, like the pigeons’ pecks, can bridge the gap and keep the memory alive.