The C0herence Principle
From my understanding, the Coherence principle is knowing when and when not to add extraneous information to a project. They argument made in the book brings the notion that because students are used to having video games and youtube, they need lots of bells and whistles. This can lead to the addition of elements that are completely unecessary in order to make the project feel more interesting. For example when looking back at the HTML Editor video I created, I link out to a youtube video of a cat playing piano.
The Idea was that this video is long, and the voice in pretty monotone. Having something fun may peak interest. It got the okay from my colleagues but in retrospect maybe that bit was unnecessary.
We could never decide of a royalty free form of music to use in the background, Clark & Mayer recommends no background music be used as it is no stong evidence to support that it helps.
Source:
Peng Liu: Cognitive Theory of Multimedia Learning, Coherence Priciple
e-Learning and the Science of Instruction; Ruth Colvin Clark • Richard E. Mayer