The basic principles of this theory will be explained in the following section. These studies marked the first systematic objective measurement of the effects of imagery on memory. Before reviewing these effects, a brief description of the assumptions and components of this theory is needed. Dual Coding Theory proposes that memory consists of two separate but interrelated codes for processing information one verbal and the other visual. The verbal and visual systems can be activated independently, but there are interconnections between the two systems that allow dual coding of information.
Information is stored in discrete, sequential units that are called logogens.
In contrast, the visual system specializes in processing and storing image or picture-like representations. Processing in the visual system is believed to be more holistic and based on continuous organizational units termed imagens . A verbal representation, on the other hand, requires a sequential description of each individual element. Thus, in this type of representation, the level of detail is directly proportional to the length of the description. Representational processing refers to the activation of a particular type of memory code by the corresponding type of stimulus.