38 Animal Intelligence 



will never be the use here. The word motive will always 

 denote that sort of consciousness. Any one who thinks 

 that the act ought not to be thus subdivided into impulse 

 and deed may feel free to use the word act for impulse or im- 

 pulse and act throughout, if he will remember that the act 

 in this aspect of being felt as to be done or as doing is in 

 animals the important thing, is the thing which gets asso- 

 ciated, while the act as done, as viewed from outside, is a 

 secondary affair. I prefer to have a separate word, impulse, 

 for the former, and keep the word act for the latter, which it 

 commonly means. 



Starting, then, with its store of instinctive impulses, 

 the cat hits upon the successful movement, and gradually 

 associates it with the sense-impression of the interior of the 

 box until the connection is perfect, so that it performs the 

 act as soon as confronted with the sense-impression. The 

 formation of each association may be represented graphi- 

 cally by a time-curve. In these curves lengths of one milli- 

 meter along the abscissa represent successive experiences 

 in the box, and heights of one millimeter above it each 

 represent ten seconds of time. The curve is formed by 

 joining the tops of perpendiculars erected along the abscissa 

 i mm. apart (the first perpendicular coinciding with the y^ 

 line), each perpendicular representing the time the cat was 

 in the box before escaping. Thus, in Fig. 2 on page 39 the 

 curve marked 12 in A shows that, in 24 experiences or 

 trials in box A, cat 12 took the following times to perform 

 the act, 160 sec., 30 sec., 90 sec., 60, 15, 28, 20, 30, 22, n, 15, 

 20, 12, 10, 14, 10, 8, 8, 5, 10, 8, 6, 6, 7. A short vertical line 

 below the abscissa denotes that an interval of approximately 

 24 hours elapsed before the next trial. Where the interval 

 was longer it is designated by a figure 2 for two days, 3 for 

 three days, etc. If the interval was shorter, the number of 



