The Coherence Principle
People learn more deeply from a multimedia message when extraneous material is excluded rather than included. The rationale for the coherence principle is that people are better able to focus on the essential material if we eliminate extraneous material that could distract them. This principle was supported in 22 out of 23 experimental tests,yielding a median effect size of 0.86. For example, students who learned from a multimedia lesson on how a virus causes a cold performed better on a transfer test if the lesson did not contain seductive details—sentences that gave interesting but irrelevant facts about viruses (Mayer, Griffith, Jurkowitz,&Rothman,2008).Similarly, students who
learned from a narrated animation on lightning formation performed better on a transfer test if the lesson did not also contain short video clips depicting lightning strikes (Mayer,Heiser, &Lonn,2001). Concerning boundary conditions, reviews of the coherence principle suggest the effects may be strongest for learners with low rather than high working memory capacity, when the lesson is systempaced rather than learner paced, and when the extraneous material is highly interesting rather than neutral (Mayer & Fiorella, in press; Rey, 2012)