Modification by Experience 233 



pecking at a string or some such object. In other cases, as 

 we have seen, these tests should be classed rather with the laby- 

 rinth method, as requiring merely that the chick should run 

 out at a given definite place (393). Porter tested English 

 sparrows with boxes containing food, which could be entered 

 by pulling a string fastened to a latch, or by pushing the string 

 into the wire netting with which one side of the box was cov- 

 ered (Fig. 1 6). The sparrows learned very quickly; one of 

 them by the tenth test had left out all unnecessary move- 

 ments (344). In later experiments a cowbird and a pigeon 

 also learned to open a similar box. Before beginning the 

 test the birds were accustomed to being fed in the box with the 

 door open. Their first success in opening the door lay in 

 accidentally clawing or pecking at the proper point, and in 

 later trials the action was simplified ; thus the birds learned 

 not to attack other parts of the box, to use the bill instead of 

 the claws, and to stand on the floor beside the box instead of 

 hopping upon it. A point of some interest arises in connection 

 with the fact that one or two of the birds, for instance the male 

 pigeon, opened the door in the simplest possible way, although 

 not very quickly, the first time they tried it, and that these 

 birds showed very little improvement in speed through sub- 

 sequent trials ; whereas the ones that had the most difficulty 

 about the first execution of the act ultimately reduced their 

 speed much below that of the others. It is possible, as Porter 

 suggests, that "greater difficulty and therefore more vigorous 

 activity on the part of the animal in the initial trials of any 

 series may naturally be expected to lead to more rapid prog- 

 ress in the later ones" (345). In Rouse's test of the pigeon 

 by the puzzle-box method, it showed less aptitude than that 

 displayed by the English sparrow (371). 



Small tested his white rats with two boxes containing food. 

 One could be entered by digging away the sawdust which was 



