Richard E. Mayer has developed a set of instructional design principles that are based on experimental research studies and grounded in a theory of how people learn from words and pictures. Learn more about Mayer’s cognitive theory of multimedia learning from his books including: Multimedia Learning: http://www.amazon.com/Multimedia-Learning-Richard-E-Mayer/dp/0521735351 E-learning & the Science of Instruction: http://www.amazon.com/Learning-Science-Instruction-Guidelines-Multimedia/dp/0470874309/