The purely physical and economic factors of technique do not interest him at all, but when a technical arrangement makes a psychophysical achievement more difficult or more easy, it belongs in the sphere of the psychologist, and just this aspect of the work may become of greatest importance for the total result.  In all three of these directions, that is, with reference to the technical, to the physiological, and to the purely psychical, the scientific management movement has prepared the way.  The engineers of scientific management recognized, at least, that no part of the industrial process is indifferent, even the apparently most trivial activity, the slightest movement of arm or hand or leg, became the object of their exact measurement.  The stopwatch which measures every movement in fractions of a second has become the symbol of this new economic period.  As long as special psychological experiments in the service of industrial psychology are still so exceptional, it may, indeed, be acknowledged that the practical experiments in the service of scientific management have come nearest to the solution of these special psychotechnical problems.

To proceed from without toward the centre, we may begin our review with the physical technique of the working conditions and its relations to the mind.  Tue history of technique shows on every page this practical adjustment of external labor conditions to the psychophysical necessities and psychophysical demands.  No machine with which a human being is to work can survive in the struggle for technical existence, unless it is to a certain degree adapted to the human nerve and muscle system and to man’s possibilities of perception, of attention, of memory, of feeling, and of will.  Industrial technique with its restless improvements has always been subordinated to this postulate.  Every change which made it possible for the workingman to secure equal effects with smaller effort or to secure greater or better effects with equal effort counted as an economic gain, which was welcome to the market.  For instance, throughout the history of industry we find the fundamental tendency to transpose all activities from the great muscles to the small muscles.  Any activity which is performed with the robust muscles of the shoulder when it can be done with the lower arm, or labor which is demanded from the muscles of the lower arm when it can just as well be carried out by the fingers, certainly involves a waste of psychophysical energy.  A stronger psychophysical excitement is necessary in order to secure the innervation of the big muscles in the central nervous system.  This difference in the stimulation of the various muscle groups has been of significant consequence for the differentiation of work throughout the development of mankind.[25] Labor with the large muscles has, for these psychophysical reasons, never been easily combined with the subtler training of the finer muscles.  Hence a social organization which obliged the men to give their energy