A Precision Liquid Feeding System Controlled by Licking Behavior.

Hulse (1960) built a tiny pump that gives a rat one drop of water each time it licks.

The pump hooks to a metal spout. Circuits count licks and open a valve for a set time.

Engineers can set drop size from 0.002 ml to 0.02 ml. The rig runs for weeks without a person in the room.

The paper shows blueprints, not data. It tells you how to copy the machine.

The author says the pump keeps working after thousands of licks.

DAVIS (1961) built a drinkometer that only records licks; Hulse (1960) adds the next step by also giving the water.

Dardano (1972) later used the same idea to show that lick rate rises when food comes on a tight schedule.

Quinsey (1972) put shock on licks and found big drops in drinking, proving the lick itself works as an operant that can be punished or avoided.

Gurley (2019) keeps the spirit alive with a $200 Raspberry Pi chamber, swapping 1960s tubes for open-source code.

If you run rodent studies, this paper gives you the grand-daddy design for precise liquid reinforcers. You can still copy the valve timing logic in modern Arduino code. Tight control of volume per response keeps reinforcer size constant across sessions, giving cleaner data when you test schedules or punishers.