164 DOGMATISM AND EVOLUTION 



give rise to a weakened impulse, yet the feature in question may 

 well enough be entirely disconnected with the peculiar experience, 

 and the incipient differentiation of A that thus arises may count 

 for nothing in the ultimate result. Speaking generally, then, we 

 may say that the effect of an unsuccessful B is to weaken the 

 impulse to B whenever A occurs. Now in numbers of cases the 

 weakened impulse is immediately reinforced by success ; in others 

 it is further sapped by failure ; and the two effects may for some 

 time cancel each other without other manifest issue than the 

 heightening of attention. 



What is necessary for the learning-process is a reorganization 

 of the sense-experience A in the two classes of cases; not that 

 new elements should be brought to consciousness, but that the 

 old should be given a new emphasis, so that feeling and active 

 response may attach to the really important marks. The trial- 

 and-error is not simply a selection between movements, but a 

 selection between candidates for the focus. In the latter aspect, 

 as in the former, we have no reason to suppose anything more 

 recondite than a process of summation. A comparatively ob- 

 scure feature, which when responded to by B is repeatedly and 

 without exception succeeded by unpleasant after effects, and 

 when responded to by the modified B' as invariably leads to 

 pleasant after effects, must finally make its way to the center of 

 attention; while the various false cues, leading to conflicting 

 results, retire into the background. 



Now where the recognition of A' (for example) is attended 

 with distinct effort and even when this is no longer generally 

 the case it may still occasionally happen this recognition is its 

 discrimination from a possible A ", as the movements of hesitation 

 suffice to indicate. Thus A' and A" sustain a quasi-logical rela- 

 tion to each other, as well as to the vaguer image A' -or- A" of 

 which they are alternative fillings-in. The significance of each 

 is partly that it is not the other. The first impression may be, 

 for example, of a moving something to be attacked or to be 

 avoided; and the aroused attention then amplifies the image so 



