Systemic-structural activity theory (SSAT), founded by Gregory Bedny, is a relatively new unified framework for the study of efficiency of human performance, equipment, and software design. This book presents new recently obtained data in the field of SSAT that can be used in the study of efficiency and complexity of human performance. With increased cognitive demands to task performance, psychological methods of study of human activity play an important role. New principles and revised methods for the study of human work are supplemented by practical examples in manufacturing, construction industry, aviation, and human-computer interaction. Features: Presents new SSAT data Offers, for the first time, comparative analysis of studying efficiency and productivity from the perspective of ergonomics, psychology, and economics Includes examples of evaluation of economic efficiency of ergonomic innovations Provides advanced self-regulative models of activity and of all cognitive processes that describe strategies of task performance Introduces a new efficient method of morphological and analytical quantitative analysis Discusses new methods of evaluation of complexity and reliability of highly variable computerized and computer-based tasks Work Activity Studies Within the Framework of Ergonomics, Psychology, and Economics presents a comprehensive unified psychological theory that can be utilized as a general approach to the study of human activity not only for ergonomists and psychologists, but also for economists that study the efficiency of human performance.