The temporal pattern of unconstrained drinking: Rats' responses to inversion and identity constraints.
Rats keep the same daily water intake under weird timing by licking faster when drinking time is cut.
01Research in Context
What this study did
Researchers watched rats drink water while food pellets arrived on fixed schedules. They flipped the normal timing and repeated identical intervals to see how the animals coped. The team tracked every lick and the total time spent drinking.
What they found
Even when the schedule was turned upside-down or copied, the rats kept their daily water intake the same. They just licked faster to make up for the shorter drinking windows. Total licks and total water stayed steady even though drinking time dropped.
How this fits with other research
Falk (1966) showed that longer fixed-interval schedules make rats drink more water. The new study seems to clash with that idea because intake stayed flat no matter how the schedule was twisted. The difference is focus: Falk (1966) changed interval length, while Delamater et al. (1986) kept interval length the same but reordered or repeated it. Nelson et al. (1978) had already shown that a 60-second interval triples intake; the 1986 paper reveals that rats defend that higher intake by licking faster when time is squeezed. Baer (1974) proved that any periodic feeding creates polydipsia; this study adds that once the drinking is established, rats adjust lick rate to guard the total amount.
Why it matters
When you set a reinforcement schedule, clients may develop adjunctive behaviors like extra drinking or pacing. This study reminds you that the behavior’s form can shift while the amount stays constant. If you shorten session time or rearrange intervals, watch for faster or more intense adjunctive responses. Use lick-rate or step-count data to see if the client is compensating for lost time. Adjust the schedule or provide alternate outlets to keep the behavior within healthy limits.
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02At a glance
03Original abstract
Rats obtained all of their water by licking a metal tube during a series of daily 1-hour sessions. When the tube was freely available throughout, each rat showed the classic temporal pattern of unconstrained drinking: As the session progressed, drinking bouts generally grew shorter and pauses grew longer. In subsequent sessions the tube was opened and closed independently of the rat's behavior, on a schedule that gave the rat a chance to duplicate the exact inverse of its unconstrained baseline pattern. Thus, as the inversion session progressed, the opportunities to drink generally grew longer and the enforced pauses grew shorter. When the rats were forced away from their unconstrained patterns of drinking and pausing, their total time spent drinking consistently fell short of previous values, but total licks and volumetric intake remained at previous levels. The same results occurred under an identity schedule, a series of openings and closings that duplicated the unconstrained pattern of drinking and pausing. The results have implications for theories that assume that instrumental performance under schedule constraint derives from the animal's defense of a measured set-point.
Journal of the experimental analysis of behavior, 1986 · doi:10.1901/jeab.1986.45-5