This author states that early man's fears and distrust of fellow man are basic phenomena, which he postulates were caused by lack of communication—a complex process requiring intelligence and understanding. Methods of classroom communication determine the amount of learning by students. Audiovisual materials used in conjunction with proven teaching methods interact with perceptor sensory mechanisms through which learning is accomplished. Various kinds of audiovisual aids are compared and assessed: chalkboards, the overhead projector and programmed learning are discussed at length but author states much research is still needed before definitive conclusions can be drawn.