Visual representation allows for the development of spatial memory in humans. A drawing of a guitar may not help a student learn to play the instrument if the student's brain is more attuned to semantic and conceptual processing; however, if the student assimilates information best through visual-spatial means, this may be a very effective technique in teaching him to play this instrument.
Brain cells tag specific visual memories, activating those memories even before they are consciously recalled. This suggests that, although a student may not remember a specific memory of the drawing of the guitar, he has knowledge of the structure of the guitar. This, however, is not a substitute for physically playing the guitar, as motor learning and repetition are what allows a person to play the instrument time and again.
Motor learning is controlled by the cerebral cortex in humans and other mammals. It allows them to learn and recall new motor movements, which is important for the ability to play an instrument and to be able to repeat this process each time the instrument is played. Therefore, while a drawing of a guitar may assist a student in learning to play the instrument, it is actual physical interaction with the instrument that allows the student to play the instrument repeatedly.