Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Arts and Sciences



First Advisor

Dr. Thomas R. Zentall


The principle of least effort suggests that animals should minimize effort to reinforcement. Thus, not pecking should be preferred over pecking. However, pigeons often peck when it is allowed but not required (e.g., fixed time schedules) but pecking may be adventitiously reinforced. In the present experiment, to better compare a schedule of reinforcement that requires pecking with one that requires the absence of pecking, we compared a fixed-interval (FI) schedule in which reinforcement follows the first peck after the interval has elapsed and a differential-reinforcement-of-other behavior (DRO) schedule which requires pigeons abstain from pecking for a similar interval. The delay to reinforcement was matched on a trial-by-trial basis by extending the duration of the FI to match the DRO schedule that preceded it. Of 12 pigeons, 6 preferred the DRO schedule over the FI schedule and 6 did not show a schedule preference. Those that were indifferent between the schedules had acquired the contingences, as they responded appropriately to the two schedules but had a spatial preference stronger than their schedule preference. Individual differences in the preference of the pigeons may be related to their behavior during the DRO.

Digital Object Identifier (DOI)