LABORATORY TESTS 105 



and I was also able to determine the addends in the 

 addition — i. e., whether the problem had been conceived 

 as 3+2=5 or as 2+3=5. It frequently happened that 

 in the beginning I would sometimes mistake these subdi- 

 visions, which were recognizable by the less pronounced 

 jerks, for the final number. Thus I would often respond 

 with 4 instead of 8, or 3 instead of 9, or with 3 when the 

 problem was 3+2, just as Hans had so often done. In 

 these tests, too, the difficulty of getting the number i, as 

 well as the larger numbers, came to light. Thus three 

 times in succession 17 was indicated as 4, as 9, and as 17. 

 But after some practice I was able to give numbers as 

 high as 58 and 96. The frequency of the errors of one 

 unit too many and of one unit too few is also noticeable 

 in these tests. 



We also found desirable corroboration, by trustworthy 

 subjects, of the introspective observations of the author, 

 which were reported in Chapter III, with regard to the 

 significance of concentration and the curve of attention. 

 It is hardly necessary to mention that no attempts were 

 made to influence the subjects in their accounts by asking 

 suggestive questions. The most valuable feature about 

 these tests was that the mute horse had now been re- 

 placed, as it were, by an animal capable of speech, and 

 that it was now possible to follow the same process both 

 from within and from without. Two illustrations may be 

 welcome. The one who took the part of the horse gave 

 three taps and made the following entry : " At 3 I saw a 

 slight upward jerk of the head on the part of the ques- 

 tioner ". The questioner however had thought of 4, and 

 made the following note, without knowledge of the other's 

 entry : " I was aware of extreme tension, so that it 

 was impossible for me to get beyond 3 ". Or again, the 



