A SALINE PREFERENCE IN RATS DETERMINED BY CONTINGENT LICKING.

COLWINOGRAD (1965) let rats choose between salt water and plain water.

Each lick gave a tiny sip. The rat had to keep licking to keep the drink.

Low thirst kept the test mild, so choice ruled the numbers.

The rats kept licking the 0.1 M salt water. They almost skipped the plain water.

The simple rule “lick to drink” showed a clear preference with no bowl bias.

Ballard et al. (1975) and Castilla et al. (2013) also watched rat licks under food schedules. They found more licks when food was scarce or rare.

COLWINOGRAD (1965) flips the lens: instead of asking “how much will you drink?” it asks “which drink do you pick?” Both lines show that licking is a tidy, real-time report of reinforcer value.

Johnson et al. (1994) showed that timing matters—rats drink less if water arrives near the next food pellet. COLWINOGRAD (1965) adds that the drink itself can control timing when access is lick-contingent. Together they tell us: arrange the contingency first, then read the pattern.

When you test client preference, tie the item to a simple response. A single switch press, card touch, or eye gaze can act like the rat’s lick—no bowl positions to confuse the data. Run the test at low motivation first; clear choices appear before need overwhelms taste.