Recently I came across this work from Koichi Sato at the University of Nebraska–Lincoln (his coordinates are at the bottom). I found it so clear and helpful that I asked him if I could work it into a blog and I’m happy to say he agreed. I took the liberty to add a few things, but don’t want to take any of the credit!
Richard Mayer’s Cognitive Theory of Multimedia Learning is based on a number of assumptions, namely that there are two separate channels – auditory and visual – for processing information (Paivio, 1990); there is limited channel capacity (Sweller, 1988), and that learning is an active process of filtering, selecting, organizing, and integrating information (Baddeley & Hitch, 1974).
Based upon these three assumptions, there have been 14 principles developed governing the good (and poor) use of multimedia. Herre’s the first.

Multimedia Principle:
People learn better when texts and pictures are presented together rather than from words alone.

The rest can be downloaded:

Koichi Sato, MSEd & MPH
University of Nebraska–Lincoln
Email: sw-ksato2@unl.edu
Web: go.unl.edu/unl-code