Industrial psychology is the application of various psychological techniques to the se-lection and training of industrial workers and to the promotion of efficient working condi-tions and techniques, as well as individual job satisfaction. The selection of workers for particular jobs is essentially a problem of discovering the special aptitudes and techniques, and personality characteristics needed for the job and of devising tests to determine whether candidates have such aptitudes and characteristics. The development of tests of this kind has long been a field of psychological research. Once the worker is on the job and has been trained, the fundamental aim of the industrial psycholo-gist is to find ways in which a particular job can best be accomplished with a minimum of effort and a maximum of individual satisfaction. The psychologist's function, therefore, differs from that of the so-called efficiency expert, who places primary emphasis on in-creased production. Psychological techniques used to lessen the effort involved in a given job include a detailed study of the motion required to do the job, the equipment used, and the conditions under which the job is performed. After making such a study, the in-dustrial psychologist often determines that the job in question may be accomplished with less effort by changing the routine motions of the work itself, changing or moving the tools, improving the working conditions, or a combination of several of these methods. Industrial psychologists have also studied the effects of fatigue on workers to de-termine the length of working time that yields the greatest productivity. In some cases such studies have proven that total production on particular jobs could be increased by re-ducing the number of working hours or by increasing the number of rest periods, or 'breaks', during the day. Industrial psychologists may also suggest less direct require-ments for general improvement of job performance, such as establishing a better line of communication between employees and management. From the first sentence of the passage, we learn that the primary objective of in-dustrial psychology is to study______.