BINOCULAR VISION 



before they are able to correlate their visual concepts with those pre- 

 viously established with the help of the muscle-sense. Thus, one person 

 could not tell which was the dog and which the cat, concepts formed 

 solely by the muscle-sense, until he had again felt of the cat's tail and 

 general contours of its body. In all these cases, the persons made 



D B 



FIG. 476. To ILLUSTRATE THE ILLUSION OF SUBDIVIDED SPACE. 



protective movements, because they felt as if the objects were actually 

 touching their eyes. 



While our visual judgment is something quite definite, we are very 

 prone to form wrong concepts whenever we are subjected to unusual 



FIG. 477. To ILLUSTRATE THE OVER-ESTIMATION OF VERTICAL LINES. 



conditions, such as may be established by changing the position of our 

 body as a whole or by altering the configuration of the object. Thus, 

 a space subdivided by intermediate lines seems larger than one not so 

 interrupted. Evidently, it requires a somewhat greater muscular 



