32 ROBERT M. YERKES 



TABLE 2 



Summary of Results of Training in Light-dark Discrimination. 



Electrically Illuminated Area Versus Unilluminated Area. 



Electric Shock Used as Punishment. 



The general results of the several series of reactions required 

 for doves number 3 and number 4 appear in table 2, under 

 their appropriate dates. A brief statement is given in the second 

 column of the table of the important conditions of reaction. It 

 is stated, for example, whether general illumination was used 



