A yoked-chamber comparison of concurrent and multiple schedules.

Killeen (1972) put pigeons in two linked chambers.

Each bird faced two keys.

One schedule ran on the left key, another on the right.

The study compared two set-ups.

In the concurrent set-up, the bird could hop between keys any time.

In the multiple set-up, the chamber lights changed every few seconds and only one key worked at a time.

Both set-ups used the same variable-interval food rates.

The question: do birds still match their pecks to the payoff rates when they cannot choose when the schedule changes?

Peck ratios matched food ratios in both set-ups.

If the left key paid twice as often, birds pecked it twice as much.

The exact number of pecks differed between concurrent and multiple, but the proportions stayed the same.

Matching held even when the bird had no control over schedule switches.

PLISKOFF (1963) first showed matching in concurrent schedules.

Killeen (1972) adds that the same rule works when schedules alternate on their own.

SHETTLEWORTCHARNEY et al. (1965) already saw response-rate shifts in multiple schedules tied to richer components.

Killeen (1972) links that earlier work to the matching law, showing the law is about proportions, not absolute counts.

Hopkins et al. (1977) later found pigeons usually undermatch — they split closer to 50-50 than strict math predicts.

Killeen (1972) did not test for this slight bend, so today we expect the proportions in both set-ups to fall short of perfect matching.

You can trust the matching law in both child-led and adult-controlled conditions.

If a client can freely move between tasks, reinforce each at the planned rate.

If you control task order with timers or signals, still reinforce at the same rate ratio.

The child’s behavior will follow the payoff ratio either way.

Check for undermatching after a week; adjust rates slightly if the split looks too even.