A cost-benefit analysis of demand for food.

Saunders et al. (1988) ran rats in a standard operant chamber. They varied three things at once: how big each food pellet was, how often the lever paid off, and how many lever presses the rat had to make.

The team boiled all three changes into one number they called 'unit price' — the presses needed per gram of food. Then they asked: do food eaten and lever presses line up on one curve when we plot them against this single price?

Yes. Whether the researchers cut pellet size, lowered payoff odds, or raised the response requirement, the results fell on the same demand curve and the same work curve when the x-axis was unit price.

In plain words: the animal acts as if it only cares about the final cost per gram, not how you create that cost.

Sutphin et al. (1998) extended the idea to foraging patches. When cheap patches became rare, rats stayed on the same cost curve by eating fewer but bigger meals instead of paying more. The unit-price rule still held; the rats just changed meal timing.

Baum (2025) looks at first glance to clash with R et al. Baum says ratio schedules fail at low payoff rates while interval schedules survive. The gap is method: Baum keeps response cost fixed and varies payoff timing, whereas R et al. mixed cost and payoff into one price metric. Both papers agree that molar cost matters; they just test different levers.

Jiménez et al. (2022) sweep unit price into a bigger picture. They slot cost-benefit analyses under 'behavioral cusps' that can open new repertoires. Your price curve is one example of how environmental economics shape pivotal behavior.

When you tweak reinforcer size, odds, or effort in a token system, convert all changes into one unit-price number. If the price crosses the rat’s collapse point, you can expect response and consumption to drop together. Use this to set lean but fair requirements in classrooms, feeding clinics, or vocational tasks without guessing which variable matters most.