Activating imagery in tandem with verbal association forms referential connections across the two cognitive subsystems. Dual coding theory postulates that referential connections across the verbal and nonverbal memories are stronger, more flexible than the associative connections within each separate system, because they add a level of meaning. (one to many)

Associative structure:  A within-system network of links and references.  The functional connections of logogens to each other (in the verbal subsystem) or of imagens to each other (in the nonverbal subsystem).

Imagens:  Representations from which mental images are generated.  Imagens correspond to natural objects, holistic parts of objects, and natural groupings of objects.

Logogens:  A hypothetical verbal representation that registers perceptual word information and makes a word response available when enough relevant information has accumulated.

Referential availability:  The probability that cues to one subsystem will be able to make associations to memories in the other subsystem, or that logogens will activate imagens and vise versa.  The capacity for stimuli to simultaneously activate memories in both subsystems is a function of the availability of referential connections.

Referential connection:  A between-system structural connection or “access route”  that permits activation of memory in one system to trigger activity in the other representational system.  An example of a simple referential connection is the tie between the image of an object and its name.