232 



PSYCHOLOGY. 



retinal impression. Prepare a sheet with the figures shown 

 in Fig. 57 strongly marked upon it, and get by direct fixa- 

 tion a distinct after-image of each. 



Project the after-image of the cross upon the upper left- 

 hand part of the wall, it will appear as in Fig. 58 ; on the 

 upper right-hand it will appear as in Fig. 59. The circle 



Fig. 58. 



Fig. 59. 



similarly projected will be distorted into two different 

 ellipses. If the two parallel lines be projected upon the 

 ceiling or floor far in front, the farther ends will diverge ; 

 and if the three parallel lines be thrown on the same sur- 

 faces, the upper pair will seem farther apart than the lower. 

 Adding certain lines to others has the same distorting 

 effect. In what is known as Zollner's pattern (Fig. 60), the 

 long parallels tip towards each other the moment we draw 

 the short slanting lines over them yet their retinal images 



yyxxy^ 



y 



/ 



y y y y y 



y y y y y 



■V^^^ 



^ 



^OOOs^OOs 



yyyyyyyyy^y y y y y 



^ y y y y 



Fig. 60. 



are the same they always were. A similar distortion of 

 parallels appears in Fig 61. 



Drawing a square inside the circle (Fig. 52) gives to the 

 outline of the latter an indented appearance where the 

 square's corners touch it. Drawing the radii inside of one 



