A second critical idea of the sequential view is that associations may differ not only in strength but qualitatively, e.g., SN-US and SR-US associations, while differing qualitatively may be of equal strength. Third, the signal capacity acquired by some CS plus thememorycompoundis not easily altered by some subsequent form of training. While this is generally the case, we have in mind here, particularly, that extinction normally has little effect on previously acquired associations, either excitatory or inhibitory (see especially Capaldi, Martins, & Altman, 2009). For example, the SR-US association formed under consistent reinforcement (CRF) is little altered by SN being retrieved on N trials in extinction, amatter considered in greater detail later.