Ran 15 male albino rats in alleys for water reinforcement with intertrial intervals (ITIs) similar to the intervals typically used in studies of intracranial reinforcement. When deprived over 15 hrs Ss ran faster with very short ITIs (7 sec) than with longer ITIs (95 sec). Comparisons with rats described in other studies running for intracranial reinforcement leads to the conclusion that, regardless of what kind of reinforcer is used, rats run faster for a reinforcer when ITIs are only seconds long rather than over a minute. (17 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)