Mayer's particular area of interest is multimedia and how it can be deployed to help students more deeply understand concepts. Mayer has developed a cognitive of theory of multimedia learning and has developed research-based principles for how to design learning environments (see his Principles for Multimedia Learning below). He has published many articles and several books about multimedia learning, the most recent being The Cambridge Handbook of Multimedia Learning, which he edited.

By using multiple modes of media, such as words, sounds, pictures and simulations, Mayer says instructors can help students build connections and integrate new information with prior knowledge. In his research Mayer has found that when words and pictures are presented together, as in a narrated animation, for example, students perform well on both retention (the ability to recall what they've learned) and transfer (the ability to apply what they've learned to solve a problem).

Mayer acknowledges that not all subject matters lend themselves to multimedia presentation. And even when they do, he does not advocate throwing a bunch of pictures, animations, sound, and words together to make PowerPoint presentations without carefully thinking about the effect on learning.

"Some of the research is showing that it's very easy to create bad PowerPoint presentations that actually stifle learning because they present too much information too quickly," says Mayer. "Sometimes instructors have the false idea that they're teaching because they are presenting information."

His research began before PowerPoint or the Internet made its way into instruction, first studying how illustrations and words written on paper impacted learning in the sciences and mathematics. In the past decade, as Internet technology and computers have made creating and using multimedia easier than ever, his research has increasingly focused on digital applications, such as simulations and virtual reality.

"Good instruction is good instruction," says Mayer. "Some things can be done better with computers, such as demonstrations and presentations of graphics. But there's a lot of bad, really ineffective instruction on the web. The bottom line is that you have to have a good idea of the cognitive change you want to make. I call it a learner-centered approach to teaching as opposed to a technology-centered approach."

Mayer is currently participating in a Mellon-funded research project at UCSB to study how technology can be used in large lecture courses to improve student learning. He is using an audience response (also known as "clicker") system in one of his courses and studying whether it can enhance student participation and help students become better problem solvers.

"I hope it will engage the students and get them to learn more deeply and participate more in class," says Mayer. To measure if the technology has an impact, Mayer will compare student grades on exams with those of the students in last year's class, which was taught in the same way except for the use of the audience response system.

Mayer believes educational uses of technology should be more widely studied across the UC campuses. "In the UC system we're a research university and we certainly want to use technology to enhance learning but it's also a research topic itself," he says. "It's worthwhile to do some research on the effects of educational technology to figure out how students learn, which students benefit, and what are the best ways to use technology."
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Mayer's principles for multimedia learning are:
1. The Multimedia Principle: Students learn better from words and pictures than from words alone.

2. The Spatial Contiguity Principle: Students learn better when corresponding words and pictures are presented near rather than far from each other on the page or screen.

3. The Temporal Contiguity Principle: Students learn better when corresponding words and pictures are presented simultaneously rather than successively.

4. The Coherence Principle: Students learn better when extraneous words, pictures and sounds are excluded rather than included.

5. The Modality Principle: Students learn better from animation and narration than from animation and on-screen text.

6. The Redundancy Principle: Students learn better from animation and narration than from animation, narration and on-screen text.

7. The Individual Differences Principle: Design effects are greater for low-knowledge learners than for high-knowledge learners and for high-spatial learners than for low-spatial learners.