Observing behavior: effects of rate and magnitude of primary reinforcement.

The team worked with pigeons in a lab chamber.

Birds could peck a small key to turn on colored lights.

These lights sometimes signaled upcoming food.

The researchers then cut the food rate or size.

They watched how this changed the birds’ key pecks.

Less food or smaller pieces quickly cut key pecks.

The drop was smooth: the leaner the payoff, the fewer the pecks.

Birds also slowed most when the key took extra effort.

Hirota (1974) saw the same drop, but only when the lights were mixed-schedule, not multiple-schedule.

The two studies line up: lean payoff cuts observing when the stimulus is weak.

Northup et al. (1991) found an upside-down U: bigger food first helped, then hurt, regular lever pressing.

Moxley (2002) never saw the upside; observing only fell.

The gap is procedural: J used progressive-ratio levers for food, while A used simple observing for signals.

Ballard et al. (1975) showed less food raised schedule-induced drinking.

Moxley (2002) shows less food lowers observing.

Together they warn: cutting payoff can spike one side behavior while sinking another.

When you assess conditioned reinforcement, keep food rate and size the same across trials.

A thinner schedule can make a client “check out,” not because the stimulus lost value, but because the primary paycheck shrank.

Lock the edible plan first; then you’ll know if the social praise or token really works.