Laws and Hypotheses for Behavior 247 



or less likelihood that the same current will be conducted 

 from the former to the latter rather than to some other place. 

 The strength or weakness of the connection is a condition 

 of the synapse. What condition of the synapse it is remains 

 a matter for hypothesis. Close connection might mean pro- 

 toplasmic union, or proximity of the neurones in space, or a 

 greater permeability of a membrane, or a lowered electrical 

 resistance, or a favorable chemical condition of some other 

 sort. Let us call this undefined condition which parallels 

 the strength of a connection between situation and response 

 the intimacy of the synapse. Then the modifiability or 

 connection changing of a neurone equals its power to alter 

 the intimacy of its synapses. 



As a provisional hypothesis to account for what satisfies 

 and what annoys an animal, I suggest the following : 



A neurone modifies the intimacy of its synapses so as to 

 keep intimate those by whose intimacy its other life pro- 

 cesses are favored and to weaken the intimacy of those 

 whereby its other life processes are hindered. The animal's 

 action-system as a whole consequently does nothing to avoid 

 that response whereby the life processes of the neurones 

 other than connection-changing are maintained, but does 

 cease those responses whereby such life processes of the 

 neurones are hindered. 



This hypothesis has two important consequences. First : 

 Learning by the law of effect is then more fully adaptive for 

 the neurones in the changing intimacy of whose synapses 

 learning consists, than for the animal as a whole. It is 

 adaptive for the animal as a whole only in so far as his or- 

 ganization makes the neurones concerned in the learning 

 welcome states of affairs that are favorable to his life and 

 that of his species and reject those that are harmful. 



Second : A mechanism in the neurones gives results in 



