PSYCHOLOGY AND TESTIMONY 473 



anything at all with his left hand. This of itself would not be sur- 

 prising, it being a phenomenon familiar in all sorts of sleight-of-hand 

 performances; but the striking fact was developed that of these eight- 

 een non-observers fourteen were included among the twenty men (or 

 thereabout) 2 who had judged a dark blue to be lighter than a certain 

 lighter gray. " That coincidence," says Professor Miinsterberg, " 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 

 Miinsterberg 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 com- 

 mon; 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 keen- 

 witted 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 atten- 

 tion 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 bright- 

 ness and of falling into the trap laid for him in the sleight-of-hand 

 performance. Professor Miinsterberg 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 dif- 

 ferently colored paper squares is the darker carries with it a high prob- 

 ability 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 

 2 " About one fifth of the men " is Professor Munsterberg's statement. ' 



