In his book Multimedia Learning, University of California professor, Richard Mayer, discusses the idea of using on-screen visuals that are above all truly visual, with little or no text. Mayer offers good evidence that this approach is in many cases the most effective. This can be understood by examining two effects outlined by Mayer: The Modality effect and the Spatial Contiguity effect.

Under the Modality effect we can say that people understand multimedia presentations better when words are presented as narration (i.e, presenter speaking) rather than as on-screen text. Mayer says that we have two channels for processing information from a multimedia presentation: a visual channel and an auditory channel. In many cases, says Mayer, a person's visual processing channel will become overloaded if text is added to the on-screen image/animation resulting in less understanding. This contradicts conventional wisdom (and practice) that "more is better" -- many times it is not.

But this is not to say that you can not place a limited amount of text with an image or on-screen animation. Mayer notes, too, citing the Spatial Contiguity effect, that there are clearly occasions when people can benefit from text being included on-screen, so long as the text is near the image or animation, allowing learners to make clear, quick connections between text and images.

Jean-luc Doumont, an engineer with a doctorate in physics from Stanford University, speaking specifically about "PowerPoint presentations" says something very similar about using text and images on a slide in the February issue of Technical Communication (article available on Amazon). Doumont advocates maximizing the signal-to-noise ratio and advices presenters to "...express a message unambiguously with as little text as possible." Says, Doumont:

"Because visual codings are in essence ambiguous, effective slides almost always include some text: the message itself, stated as a short sentence (thus including a verb). Beyond this text statement, the message should be developed as visually as possible...."

I have said it repeatedly, as have many others before me: slides (if you use them at all) should be as visual as possible. The words come out of your mouth. An important on-screen word or two, or short declarative sentence placed near the image is sometimes helpful. But bulleted lists are almost never preferable; and they certainly need not be the default slide format as they are today in both Microsoft's PowerPoint and Apple's Keynote.

There are myriad ways you can use text along with images. Below are just five slides from a talk I gave on blogging in 2006. These five visuals represent about 60-90 seconds. The first three slides appeared for a total of about 10-15 seconds; the Microsoft slide was on screen longer as I explained the difference between a company's website and a blogger's website who also happens to work for that same company. Later, I went on to explain what a "good blog" is covering, such areas as the importance of updating regularly (using the shark analogy, one often used).

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(Sample narration):You have heard me say before that "presentations are like conversations." Which is true, but (slide1) blogging is like "conversation" in a sense as well because.... But not just any kind of conversation (slide 2), "Naked Conversations"... In fact, that is the name of (slide 3) this great book.... But what's the difference between, say, (slide 4) Microsoft's website and famous Microsoft blogger, Robert Scoble's website....

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(Sample narration): Blogs are like sharks. Sharks have to keep moving...or die. A blog has "to keep moving," keep progressing, be consistently updated...or it will die (as many blogs have)....

Photos are from iStockPhoto, where I get most of my images.