Cognitive load is the amount of resources needed by the working memory at any point in time to process information. When a person experiences cognitive overload, the process by which information is consolidated and stored in long-term memory is interrupted, and learning suffers. According to educational psychologist John Sweller, “two of the most important [sources of overload] are ‘extraneous problem-solving’ and ‘divided attention’” (125). Studies on hypertext media and reading demonstrate that embedded links, videos, and images cause readers to comprehend less of a text than traditional printed media. One result of the cognitive load experienced by Internet users is that web page visitors power skim, rather than deeply read, information presented online.

Deep reading refers to the combination of sustained attention and “the highly active and efficient deciphering of text and interpretation of meaning” (64). Silent deep reading enables readers to make connections and arrive at their own unique understanding of the text—what Carr refers to as deep thinking. Deep reading involves disengaging from outward stimuli to focus on internal stimuli, and this reflective state provides the brain with the resources for deep thinking. By contrast, the Internet as a medium demands focus on external stimuli—links, images, audio, messages—and the process of internal reflection and synaptic development is halted.