Stimulus Effects On Behavior Allocation In Three-alternative Choice.

Pigeons pecked three keys in a chamber. Each key had its own color and its own rate of grain payoff.

The researcher changed how different the colors looked. He wanted to know if color difference, not just grain odds, swayed where the birds pecked.

Birds spread pecks across keys based on two things at once: grain rate and color gap.

A math model that included both factors fit the data best. Color difference pushed choice even when grain odds stayed the same.

Davison et al. (1995) showed that adding a clear signal lets you shape birds away from strict matching. Evenhuis (1996) now says the look of that signal also counts.

Hopkins et al. (1977) found pigeons prefer keys that tell them grain is coming. The new study agrees: stimulus information moves choice beyond plain payoff.

Gomes‐Ng et al. (2026) move the lens from outside colors to the birds’ own past moves. Their work extends Evenhuis (1996) by showing that self-produced stimuli can top external ones.

When you set up concurrent schedules, do not pick colors or icons at random. Make the better payoff option look more different from the others. A sharper visual gap can nudge responding even when the reinforcer rate is only slightly better. Try it in token boards, response allocation games, or choice-based DTT.