anything at all with his left hand. This of itself would not be surprising, it being a phenomenon familiar in all sorts of sleight-of-hand performances; but the striking fact was developed that of these eighteen non-observers fourteen were included among the twenty men (or thereabout)[1] who had judged a dark blue to be lighter than a certain lighter gray. "That coincidence," says Professor Münsterberg, "was of course not chance. In the case of the darkness experiment the mere idea of grayness gave to their suggestible minds the belief that the colorless gray must be darker than any color. They evidently did not judge at all from the optical impression, but entirely from their conception of gray as darkness. The coincidence, therefore, proved clearly how very quickly a little experiment such as this with a piece of blue and gray paper, which can be performed in a few seconds, can pick out for us those minds which are utterly unfit to report whether an action has been performed in their presence or not. "Whatever they expect to see they do see; and if the attention is turned in one direction, they are blind and deaf and idiotic in the other." That the coincidence is not a matter of chance may be admitted as practically certain; and yet there is ample room for disputing the inference which Professor Münsterberg draws from it. He finds in it a triumphant proof of the adequacy of an extremely simple and special little test for a sweeping conclusion as to the general powers of observation of the men subjected to it. But surely there is another possible explanation. There is one thing that both the color test and the sleight-of-hand test have in common; the danger of a wrong answer in either case may lie chiefly in a failure on the part of the student to grasp firmly and clearly the exact and full import of the question. The man that is alert and keenwitted and intent in his attitude toward the test will both know exactly what is meant by the question of the relative brightness of the two colored papers and be on his guard as to the possibility of a trick (for that is what it is) in the attempt to concentrate his attention upon the spectacular doings of the right hand. The man less keyed up to the requirements of the tests will be in danger both of failing to make the requisite discrimination in the question of brightness and of falling into the trap laid for him in the sleight-of-hand performance. Professor Münsterberg may have (but he certainly does not mention it) confirmatory evidence of the conclusion he draws from the coincidence; but on the face of it that coincidence may quite as plausibly be accounted for in the manner I have indicated as it is by the supposition that an inability to determine which of two differently colored paper squares is the darker carries with it a high probability that the observer is "utterly unfit to report whether an action has been performed in his presence or not." The common observation of every-day life is of a radically different character from what is
- ↑ "About one fifth of the men" is Professor Münsterberg's statement.
