Response bias and the discrimination of stimulus duration.

Researchers worked with pigeons to study how reinforcement timing affects choices. The birds pecked keys when lights stayed on for different lengths of time. Scientists changed how often correct pecks earned food to see if birds would favor one duration over another.

Changing the food payoff ratio made pigeons biased toward the richer side. They pecked more on the key that paid off better, even when both lights lasted the same time. The birds still told short from long correctly - their accuracy stayed sharp.

Smith (1967) first showed pigeons could judge stimulus duration, but only looked at accuracy drops with delays. Cicerone (1976) added the bias twist - proving payoff ratios steer preference without hurting discrimination.

Parmenter (1999) later tested matching law on self-control choices and found the same pattern: relative reinforcement rules. The 1976 bias result became the foundation for this broader matching-law work.

Gentry et al. (1980) used similar concurrent-chain methods to study delay choice. They confirmed that both relative and absolute delays matter, extending the 1976 finding beyond simple duration tasks.

When you set up reinforcement schedules, remember that payoff rates create response bias separate from true skill. If a child picks blue cards more than red, check whether blue pays off better, not whether they can't tell colors apart. Balance reinforcement across options to keep choices honest and avoid accidental bias in your data.