Effects of chlordiazepoxide on pausing during rich‐to‐lean transitions

Extended pausing during discriminable transitions from rich‐to‐lean conditions can be viewed as escape (i.e., rich‐to‐lean transitions function aversively). Thus, an anxiolytic drug would be predicted to mitigate the aversiveness and decrease pausing. In the current experiment, pigeons' key pecking was maintained by a multiple fixed‐ratio fixed‐ratio schedule of rich (i.e., larger) or lean (i.e., smaller) reinforcers. Intermediate doses (3.0‐10.0 mg/kg) of chlordiazepoxide differentially decreased median pauses during rich‐to‐lean transitions. Relatively small decreases in pauses occurred during lean‐to‐lean and rich‐to‐rich transitions. Effects of chlordiazepoxide on pausing occurred without appreciable effects on run rates. These findings suggest that signaled rich‐to‐lean transitions function aversively.