An information-theory model of human memory was tested in thirteen experiments which involved children (six years and older) and graduate students. The subjects conducted science investigations in laboratory and non-laboratory settings, solved problems of electrical circuits, and participated in classroom science lessons. The tasks used involved problem solving, recognition, and immediate and delayed recall. The model gave meaningful descriptions of cognitive processing, allowed isolation of several memory processes, and provided evidence of learning information processing. The differences in the kind of information processed during various cognitive tasks were due to interactions; for example, between input information and long-term memory. Problem solving tasks involved controlling and balancing "noise" in the input and output information channels; recall processing differed from problem solving by an inverse management of noise control. The data represent the first significant demonstration of Shannon's 1948 theorem on error capacity of communication channels. The model, with universal applications for describing human behavior, may allow interpretation of how and when learning occurs. (A glossary of terms and data tables are appended. A simplified diagrammatic version of the model is included.) (Author/AL)