PSYCHOLOGY AND TESTIMONY 471 



and the state of the attention or interest of the observer is wholly dif- 

 ferent in the ordinary circumstances of life from what it is when the 

 observer is being tested by the psychologist. It is entirely possible 

 that when fifty little black squares irregularly pasted on a large sheet 

 of white cardboard are exposed for five seconds to the gaze of A and 

 B, A will make a much better guess than B at their number, owing to 

 his ability to concentrate his attention or to make a swift calculation; 

 and yet that if A and B were in a hall with fifty people in it, B would 

 instinctively have a much better idea of the number of people in it 

 than A, owing to a habit of being interested in the scenes of which he 

 is a natural part and in their significance. Again A, fixing his atten- 

 tion on the end of a black pointer moving over the edge of a white 

 dial, may be vastly better able than B to get that ratio of the con- 

 sciously observed space to the consciously observed time which is the 

 velocity Professor Miinsterberg desired his students to measure in one 

 of his experiments; and yet if A and B were walking casually along 

 the street, B might be an incomparably more reliable witness on the 

 question whether an automobile was or was not exceeding the legal 

 speed limit. And this matter of the different distribution of interest 

 in different circumstances is only one of a vast number of elements 

 ■which go to making the psychologist's test highly precarious. You 

 must catch a man " in his habit as he lives," you must follow him into 

 all sorts of situations under all sorts of circumstances, internal and 

 external, before you can decide what value to attach to his statement 

 as to the facts that come into his ordinary experience of daily life. 

 The man who may be too dull-witted to understand the psychologist's 

 question, too lethargic to make a decent observation of what is put 

 before him by his examiner, or too " rattled " to state correctly the 

 result of that observation, may be a man who, as he goes about his 

 work or chats with his fellows, misses nothing of the ordinary human 

 occurrences that take place around him. And, on the other hand, the 

 man of quick intelligence and keen activity who, upon demand, can 

 bring all his faculties to bear upon a subject on which he is challenged 

 to make a creditable report may, not only in spite of having this tem- 

 perament, but actually because of it, be the very man who habitually 

 takes extremely imperfect notice of the visible and audible things that 

 are going on around him all the time and that have for him no 

 significance. 



Difficulties like these — I do not say insuperable difficulties, but 

 certainly difficulties that offer enormous resistance to the investigator — 

 are inherent in the subject. But over and above these inherent diffi- 

 culties are those which attach not so much to the investigation as to the 

 investigator. As a practical proposition, Professor Miinsterberg's 

 project must contemplate the employment of the psycbological expert 

 n« an expert, strictly speaking. His report on the capacity of a witness 



