Research Cluster

Schedule-Induced Polydipsia and Adjunctive Behavior

This cluster shows how giving food on a timed schedule can make animals drink lots of water even if they are not thirsty. The studies prove the time between food bites, not the kind of food, is what starts this extra drinking called schedule-induced polydipsia. BCBAs can use these facts to spot and manage similar odd behaviors that pop up when reinforcers are delivered on fixed schedules. Knowing this helps keep clients safe from harmful side behaviors and keeps treatment plans clean.

45articles
1962–2026year range
5key findings
Key Findings

What 45 articles tell us

  1. The time gap between reinforcer deliveries — not hunger, thirst, or stress — is the main driver of schedule-induced adjunctive behavior like excessive drinking.
  2. Higher food deprivation and more frequent reinforcer deliveries both intensify adjunctive behavior, creating more opportunities for unwanted side behaviors.
  3. Signaled delays suppress adjunctive behavior more effectively than unsignaled delays, giving practitioners a low-cost tool for managing schedule-induced responses.
  4. Briefly removing the opportunity to perform adjunctive behavior can reduce it later, showing that behavioral history shapes how much of it appears.
  5. Rich-to-lean schedule shifts can temporarily boost consumption of concurrently available alternatives — watch for contrast effects when thinning reinforcement schedules with clients.
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Frequently Asked Questions

Common questions from BCBAs and RBTs

It is a pattern where animals on a food delivery schedule drink far more water than they should need, simply because the timing of food creates gaps that the drinking fills. BCBAs should know about it because the same schedule-driven mechanism can produce adjunctive behaviors in clients — things like pacing, rocking, or repetitive actions that appear during predictable gaps in reinforcement.

Look at when the behavior happens. Adjunctive behavior tends to cluster in the gap after reinforcement and before the next opportunity, especially on fixed schedules. Automatic reinforcement tends to appear more consistently across all conditions. If the behavior tracks your reinforcement schedule timing, adjunctive behavior is worth considering.

Yes. Adding signals that mark when reinforcement is available and when it is not can suppress adjunctive behavior with minimal other changes. This is a low-cost first step before redesigning the whole schedule.

It may temporarily increase. Research shows that shifting from a rich to a lean schedule can produce a brief spike in adjunctive or alternative behaviors due to a contrast effect. Monitor across several sessions before concluding the thinning is not working.

Yes. Higher deprivation intensifies adjunctive behavior, and more frequent reinforcer deliveries also increase it. If a client is highly motivated — either by deprivation or strong preference — expect more adjunctive behavior during fixed schedule gaps.