34 



L. W. SACKETT 



supposing that under normal conditions No. ii would do as 

 other animals have done, namely, begin anew when he found 

 that any part could not be 'operated. Thus, the long time of 

 any one effort usually means one small error plus a great in- 

 convenience in rectifying it. The low record for the second 

 effort on the hook was made by the animal striking the hook 

 from below instead of climbing on top as was his custom before 

 with the button and the first trial with the hook. This was 

 one of the few instances where a successful reaction tending 

 toward simplification did not materially modify the behavior 

 of the animal. 



The records of the first four devices shown in table IV are 

 represented by curve A in plate I. To obtain the curve the 

 time records for the various devices were arranged successively 

 and these results were grouped and rearranged by twos, taking 

 the first of each series, second of each, etc. This may be taken 

 as fairly representative of the learning curve of the porcupine 

 under these particular conditions. Table V was derived from 

 table IV in the following manner: The time records for each 

 device and combination were arranged successively in groups 

 of five and the results tabulated in the first six columns along 



The figures at the left in each column (table V) indicate the average number 

 of seconds taken in groups of five which porcupine No. 11 used in operating the 

 different devices and combinations. The figures at the right in each column show 

 the mean variation for the same groups. The right-hand column combines the 

 other six by averaging the two items separately along horizontal lines. 



