RESURGENCE OF CHICKS’ KEY-PECK RESPONDING WITH AN IMPRINTED STIMULUS OR FOOD AS REINFORCER

Resurgence of newborns’ operant responses that have been reinforced by phylogenetically important events has not yet been investigated. The present study investigated whether, in newly hatched chicks, resurgence of key-peck operant responses previously reinforced by delivery of either an imprinted stimulus or food as a reinforcer would recur under extinction. The possibility of intrusion into the resurgence of behavior related to the imprinted stimulus and food as phylogenetically important events was also explored. Ten chicks that were imprinted to a moving stimulus were divided into two groups, using either an imprinted stimulus or food as a reinforcer, respectively. First, their pecking a red key was shaped and maintained under a variable-interval schedule (Phase 1). After pecking rates stabilized, pecking a second, blue, key was reinforced using the same reinforcer as in Phase 1, while pecking the red key was extinguished (Phase 2). After the rates of pecking the red key were extinguished, pecking of either key was extinguished (Phase 3). Resurgence was measured as the number of pecks on the red key in the initial session of Phase 3. Most chicks in both groups showed resurgence of pecking the red key during the final extinction phase.