One of the largest ship companies had approached me—­long before the disaster of the Titanic occurred—­with the question whether it would not be possible to find psychological methods for the elimination of such ship officers as would not be able to face an unexpected suddenly occurring complication.  The director of the company wrote to me that in his experience the real danger for the great ships lies in the mental dispositions of the officers.  They all know exactly what is to be done in every situation, but there are too many who do not react in the appropriate way when an unexpected combination of factors suddenly confronts them, such as the quick approach of a ship in the fog.  He claimed that two different types ought to be excluded.  There are ship officers who know the requirements excellently, but who are almost paralyzed when the dangerous conditions suddenly threaten.  Their ability for action is inhibited.  In one moment they want to act under the stimulus of one impression, but before the impulse is realized, some other perhaps rather indifferent impression forces itself on their minds and suggests the counteraction, and in this way they vacillate and remain inactive until it is too late to give the right order or to press the right button.  The other type feels only the necessity for rapid action, and under the pressure of greatest haste, without clear thought, they jump to the first decision which rushes to their minds.  Without carefully considering the conditions really given, they explode in an action which they would never have chosen in a state of quiet deliberation.  They react on any accidental circumstance, just as at a fire men sometimes carry out and save the most useless parts of their belongings.  Of course, beside these two types, there is the third type, the desirable one, the men who in the unexpected situation quickly review the totality of the factors in their relative importance and with almost instinctive certainty immediately come to the same decision to which they would have arrived after quiet thought.  The director of the company insisted that it would be of highest importance for the ship service to discriminate these three types of human beings, and to make sure that there stand on the bridge of the ship only men who do not belong to those two dangerous classes.  He turned to me with this request, as he had heard of the work toward economic psychology in the Harvard laboratory.

As the problem interested me, I carried on a long series of experiments in order to construct artificial conditions under which the mental process of decision in a complicated situation, especially the rapidity, correctness, and constancy of the decision, could be made measurable.  I started from the conviction that this complex act of decision must stand in definite relation to a number of simpler mental functions.  If, for instance, it stood in a clear definite relation to the process of association, or discrimination, or