en. LVL] 



VISUAL JUDGMENTS 



809 



whence a fresh relay continues the impulse to the oculo-motor 

 nucleus. 



Visual Judgments. 



The psychical or mental processes which constitute the visual 

 sensation proper have been studied to a far greater degree than is 

 possible in connection with other forms of sensation. 



We have already seen that in spite of the reversion of the image 



FIG. tiOO Relations of nerve cells and fibres of visual apparatus. (Scliiifer.) 



in the retina, the mind sees objects in their proper position; this 

 is explained on p. 780. 



We are also not conscious of the blind spot. This is partly due 

 to the fact that those images which fall on the blind spot of one eye 

 are not focussed there in the other eye. But even when one looks 

 at objects with one eye, there is no blank, for the reason explained 

 on p. 790. 



Our estimate of the size of various objects is based partly on the 

 visual angle (p. 779) under which they are seen, but much more on the 

 estimate we form of their distance. Thus a lofty mountain many 

 miles off may be seen under the same visual angle as a small hill 

 near at hand, but we infer that the former is much the larger 

 object because we know it is much farther off than the hill. Our 



