72 MATHEMATICAL BIOPHYSICS OF THE CENTRAL NERVOUS SYSTEM 



Our discussion has dealt mainly with two mechanisms, and it is 

 important to distinguish the experimental situations to which they 

 were applied. The first mechanism was applied to relative discrimina- 

 tion between stimuli simultaneously presented, and the distribution of 

 "correct" and "wrong" judgments was predicted. The second was ap- 

 plied to absolute discrimination, each stimulus being presented alone, 

 and a Weber ratio was deduced. A third mechanism was first intro- 

 duced in chapter vi, and could be applied to sensitivity following adap- 

 tation. Still a fourth was suggested in chapter iii, but only as illus- 

 trating the possibility of a mechanism failing to transmit under in- 

 tense stimulation. No application to concrete quantitative evidence 

 was made of this. The last mechanism discussed here will be extended 

 in chapter xii to provide a mechanism for the discrimination of colors. 



TABLE I 

 LIFTED WEIGHTS 



