98 



HAROLD C. BINGHAM 



That the discrimination was not by some factor or factors 

 other than size, an explanation of my method during the control 

 tests will show. In the main, the same procedure, but a more 

 crude form, w r as carried out with Nos. 3, 6, 7, for with them 

 the control method was conducted less definitely from the 

 beginning of the training. 



TABLE 5 



Control Series for O 28h — O 7+ Discrimination 



Nos. 15, 16, 17, 18, 20, and 21 



March 4, 1912 



Record Sheet 1. Series 14 



The plan of the control is concisely stated in table 5. The 

 location of the source lamps was varied according to the plan 

 of the second and third columns. The illumination of the electric 

 boxes was controlled according to the last two columns. In 

 tests 1 and 2, the + or right stimulus area was considerably 

 brighter and that compartment was markedly lighter than the 

 other. In tests 3 and 4 the right stimulus was brighter but the 

 general illumination was reversed. The right compartment was 

 kept slightly darker after the fourth test than the wrong com- 



