Dual coding is the process of combining text and images when studying. Dual coding theory has its roots in the practical use of imagery as a memory aid 2500 years ago. The memory emphasis evolved into broader applications of imagery aimed at accelerating the acquisition of knowledge.  . . that increased during the Renaissance when influences from imagery mnemonics systems and formal logic brought words and things together in a “new logic” in which language was intended to mirror the structure of the world.

The practice of using both words and images provides an opportunity to remember in two formats, thus enhancing studying. These visuals can include infographics, timelines, cartoon strips, diagrams, and graphic organizers. Learners can select which graphic best suits the subject they are studying: a geometric drawing for math, or a timeline for history. MInd mapping is another method for graphics.  One of the keys to effective memory is repetition, and using several  methods for notes can reinforce and support that repetition. “Dual-coding theory argues that processing advantages for concrete over abstract (verbal) stimuli result from the operation of 2 systems (i.e., imaginal and verbal) for concrete stimuli, rather than just 1 (for abstract stimuli).” 

Different regions of the brain are engaged when using visuals than when using words. In summary, people learn best when they combine visual materials (like pictures or diagrams) with verbal materials (like words from a textbook).