12-7] IMPORTANT CHARACTERISTICS OF THE HUMAN OPERATOR 637 



I 



1.0 



0.9 



0.8 



I 0.7 



^0.6 



I 0.5 



§ 0.4 



^ 0.3 



0.2 



0.1 



70 60 50 40 30 20 10 10 20 30 40 50 



NASAL TEMPORAL 



ANGULAR DISTANCE FROM FOVEA 



Fig. 12-15 Variation of Acuity with Angular Displacement from the Fovea. 



resolvable element is five times as large.) If light falls upon the "blind spot" 

 (entrance of the optic nerve) no visual response will be obtained. 



Fig. 12-17 shows the range of sensitivity (the absolute brightness 

 required to elicit a response) of the retina as well as the extreme sensitivity 

 of the periphery. In this figure, the ordinate indicates the sensitivity of the 

 eye after dark-adaptation has taken place. Each curve presents these data 

 for a different subject. 



5 10 15 



DEGREES FROM CENTER 



Fig. 12-17 Sensitivity of the Eye as a Function of Angular Displacement from 



the Fovea. 



