Ratio size and cocaine concentration effects on oral cocaine-reinforced behavior.

Four monkeys could press a lever to get a sip of cocaine water. The team changed two things: how many presses the monkey had to make (FR 10, 30, 100, 300) and how strong the cocaine water was (0.05, 0.1, 0.2, 0.4 mg/ml).

Each day the monkey lived in a test chamber. One lever gave cocaine water, another gave plain water. The session ended after 60 minutes or 50 drinks. Scientists counted every press and every sip.

Monkeys almost never worked for plain water. They pressed hard for cocaine water. Higher cocaine strength and lower press requirement both increased drinking.

When the scientists plotted drinks against unit price (presses ÷ strength), all the points fell on one smooth curve. Unit price explained 77-92 % of the variance. The monkeys followed the same economic law that governs human shoppers.

BURNSTEIN et al. (1964) saw the same FR effect in rats that ran for water. More presses still meant more licks, showing the pattern holds across species and reinforcers.

Sanders et al. (1989) gave coffee drinkers caffeine pills or coffee. Like the monkeys, people drank more when the drug dose was higher, proving the dose-consumption link works in humans too.

Glover et al. (1976) found that richer reinforcers lengthen the pause after reward while leaving the run rate unchanged. The cocaine study adds the next layer: total consumption, not just pause, is set by unit price.

You now have a simple rule: consumptioa small group ÷ unit price. When you thin a reinforcement schedule, think of it as raising the price. If you double the task length, halve the response cost or raise the reinforcer size to keep the price constant. This math works for tokens, breaks, or edibles. Use it to predict, not just guess, how schedule changes will affect client responding.