Finally, a fourth idea is that, e.g., following extinction, an excitatory CS will not produce responding if SN is remembered. However, following extinction presentation of the excitatory CS will produce responding if SR is remembered or if neither SR nor SN is remembered. Furthermore, a non-extinguished excitatory CS will produce responding if neither SR nor SN is remembered. These matters will be considered in relation to phenomena such as renewal and reinstatement.