Laws and Hypotheses for Behavior 279 



except for their connection-systems, each being the aver- 

 age condition of the animal in question. 



Call Si and S 2 two external states of affairs, each being 

 near the indifference point for the animal in question, - 

 that is, being one which the animal does little to either 

 avoid or secure. 



Call GI and G 2 two responses which result in C^ and 2 the 

 optima or most satisfying state of affairs for i and 2. 



Call Ij and I 2 two responses which result in the continua- 

 tion of Si and S 2 . 



The only responses possible for i are Gj and Ij. 



The only responses possible for 2 are G 2 and I 2 . 



Animal i upon the recurrence of Si and C x is little or no 

 more likely to respond by GI than he was before. 



Animal 2 upon the recurrence of S 2 and C 2 is far more 

 likely to respond by G 2 than he was before. 



The fact thus outlined might conceivably be due to an 

 intrinsic inequality between 1 and O 2 , the power of equally 

 satisfying optima to influence, their antecedents being iden- 

 tical. This is not the case in the evolution of learning, 

 however. For even if, instead of O 2 , we had only a moder- 

 ately satisfying state of affairs, such as the company of 

 other chicks to (2) a i5~day-old chick, while QI was the 

 optimum of darkness, dampness, coolness, etc., for (i) an 

 earthworm, 2 would learn far, far more rapidly than i. 



The fact is due, of course, to the unequal power of equally 

 satisfying conditions to influence their antecedents. The 

 same argument holds good for the influence of discomfort. 



The ability to learn, - - that is, the possession of a con- 

 nection-system subject to the laws of exercise and effect, 



- has been found in animals as ' low ' as the starfish and 

 perhaps in the protozoa. It is hard to tell whether the 

 changed responses observed in Stentor by Jennings and in 



