Associative structures needn’t just hold between simple concepts. One might have reason to posit associative structures  between propositional elements (see section 5)  or between concepts and valences (see section 8).  But none of the proceeding is meant to imply that all structures are associative or propositional—there are other representational formats that the mind might harbor (e.g., analog magnitudes or iconic structures; see Camp 2007; Quilty-Dunn forthcoming). For instance, not all semantically related concepts are harbored in associative structures. Semantically related concepts may in fact also be directly associated (as in doctor/nurse) or they may not  (as in  horse/zebra; see Perea and Rosa 2002). The difference in structure is not just a theoretical possibility, as these different structures have different functional profiles: for example, conditioned associations appear to last longer than semantic associations do in subjects with dementia (Glosser and Friedman 1991).