DISCRIMINATIVE FUNCTIONS BASED ON A DELAY IN THE REINFORCEMENT RELATION.

Pigeons were shown to come under discrimination control when the S(D) and S(Delta) were temporally separated from reinforcement and non-reinforcement. S(D) and S(Delta) consisted of distinctive key illuminations presented separately. Responding on an FR 5 in the presence of S(D) or S(Delta) produced a third stimulus containing a schedule requirement. If this third (or interpolated) stimulus was preceded by S(D), responding in its presence produced reinforcement followed by a time-out (TO). If, on the other hand, the third stimulus was preceded by S(Delta), responding produced TO alone. In this fashion, the same stimulus and the same response requirement were imposed between S(D) and the reinforcement as between S(Delta) and the TO. In Experiment I, the schedule employed during the interpolated stimulus was FR; in Experiment II, FI. Discrimination reversal was accomplished in both experiments.