that the real proof of the value of this method cannot be offered.  This is just the reason why we selected this illustration as an example of the particular difficulty.  Wrong decisions, that is, cases in which the man on the bridge waits too long before he makes his decision and thus causes a collision of ships by his delay, or in which he rushes blindly to a decision which he himself would have condemned after quiet deliberation, are rare.  It would be impossible to group such men together for the purpose of the experiment and to compare their results with those of model captains, the more as experience has shown that an officer may have a stainless record for many years and yet may finally make a wrong decision which shows his faulty disposition.  The test of the method must therefore be a somewhat indirect one.  My aim was to compare the results of the experiments with the experiences of the various individuals which they themselves reported concerning their decisions in unexpected complicated situations, and moreover with the judgments of their friends whom I asked to describe what they would expect from the subjects under such conditions.  The personal differences in these respects are extremely great, and are also evident in the midst of small groups of persons who may have great similarity in their education and training and in many other aspects of their lives.

Among the most advanced students of my research laboratory, for instance, all of whom have rather similar schooling and practically the same training in experimental work, the product of mistakes and seconds varied between 348 and 13,335.  That smallest value occurred in a case in which the time was 116 seconds and the sum of the mistakes only 3, inasmuch as 3 cards of the most difficult group where the predominating letter occurred only 15 times were put in the wrong piles.  The shortest time among my laboratory students was 58 seconds, but with this individual the sum of the mistakes, calculated on the basis of the valuation agreed upon, was 13.  The largest figure mentioned resulted in a case in which the student needed 381 seconds and yet made mistakes the sum of which amounted to 35.  It is characteristic that the person with the smallest product felt a distinct joy in the experiment, while the one with the largest passed through painful minutes which put him to real organic discomfort.  If we arrange the men simply in the order of these products, of course we cannot recognize the various groups, as those who are quick but make mistakes and those who make few mistakes but act slowly may be represented by the same products.  The coincidence of the results with the self-characterization is frequently quite surprising.  Every one has at some time come into unexpected, suddenly arising situations and many have received in such moments a very vivid impression of their own mental reaction.  They know quite well that they could not come to a decision quickly enough, or that they rushed hastily to a wrong decision,