RETENTION INTERVALS AND DISCRIMINATIVE CONTROL

Three pigeons responded to a color display on the center key of a thre e-key chamber. Following completion of a fixed ratio schedule, the dis play changed to a vertical line and subjects had to complete a fixed i nterval schedule (FI) after which the center key was darkened and both side keys illuminated. The correct side key was determined by both th e color of the initial stimulus and the duration of the FI. Pigeons we re able to discriminate successfully when the color changed between se ssions and durations changed within sessions, when color changed withi n sessions and duration changed between sessions, and when both color and duration changed within sessions. The FI component served simultan eously as a retention interval and a discriminative stimulus. (C) 1996 Academic Press, Inc.