THE INTELLIGENCE OF MAMMALS 237 
a second time, when it usually recommenced its bitings and 
clawings, but it generally effected its escape more quickly 
than at first. The experiment was then repeated until the 
animal had perfectly mastered the means of escape. The 
time taken to escape was recorded and was found to di- 
minish, as a rule, with successive trials. 
In one set of experiments a cat was liberated from the 
box whenever she licked herself, and in another set when- 
ever she scratched herself. Although there could be no 
perceptible relation between the means employed and the 
end achieved, the cats learned to make the appropriate 
movement after being put in the box, although their asso- 
ciation curves showed a gradual descent. There is a curious 
tendency for the act to be performed less and less vigorously. 
“The licking degenerates into a mere quick turn of the head 
with one or two motions up and down with tongue extended. 
Instead of a hearty scratch, the cat waves its paw up and 
down rapidly for an instant.” 
' Previous experience is a factor which influences the quick- 
‘ness of forming associations. ‘After getting out of six or 
eight boxes by different sorts of acts the cat’s general tend- 
ency to claw at loose objects within the box is strengthened 
and its tendency to squeeze through holes and bite bars is 
weakened; accordingly it will learn associations along the 
general line of the old much more quickly. Further, its 
tendency to pay attention to what it is doing gets strength- 
ened, and this is something which may properly be called 
a change in degree of intelligence.” None of the acts per- 
formed by cats and dogs in his numerous experiments 
exhibits, according to Thorndike, any power of reasoning 
and usually no association of ideas. A point upon which 
Thorndike lays especial stress is the gradual descent of the 
curves representing the times required in forming the asso- 
