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
suggestibility, or perception, or memory, and so on, it would be
rather easy to foresee the behavior of the individual in the act of
decision, as every one of th