Abstract: | Pigeons were shown to come under discrimination control when the SD and SΔ were temporally separated from reinforcement and non-reinforcement. SD and SΔ consisted of distinctive key illuminations presented separately. Responding on an FR 5 in the presence of SD or SΔ produced a third stimulus containing a schedule requirement. If this third (or interpolated) stimulus was preceded by SD, responding in its presence produced reinforcement followed by a time-out (TO). If, on the other hand, the third stimulus was preceded by SΔ, responding produced TO alone. In this fashion, the same stimulus and the same response requirement were imposed between SD and the reinforcement as between SΔ 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. |