18 PSYCHOLOGY. 



color of the illumination. We have sufficient opportunity to investigate 

 the same colors of objects in full sunshine, in the blue light of the clear 

 sky, in the weak white light of a cloudy day, in the reddish-yellow light 

 of the sinking sun or of the candle. Moreover the colored reflections 

 of surrounding objects are involved. Since we see the same colored 

 objects under these varying illumniations, we learn to form a correct 

 conception of the color of the object in spite of the difference in illumi- 

 nation, i.e. to judge how such an object would appear in white illumi- 

 nation ; and since only the constant color of the object interests us, 

 we do not become conscious of the particular sensations on which our 

 judgment rests. So also we are at no loss, when we see an object 

 through a colored covering, to distinguish what belongs to the color of 

 the covering and what to the object. In the experiments mentioned we 

 do the same also where the covering over the object is not at all colored, 

 because of the deception into which we fall, and in consequence of which 

 we ascribe to the body a false color, the color complementary to the 

 colored portion of the covering." * 



We think that we see the complementary color through 

 the colored covering, — for these two colors together w'ould 

 give the sensation of white which is actually experienced. 

 If, however, in any way the white spot is recognized as an 

 independent object, or if it is compared with another ob- 

 ject known to be white, our judgment is no longer deceived 

 and the contrast does not appear. 



"As soon as the contrasting field is recognized as an independent 

 body which lies above the colored ground, or even through an ade- 

 quate tracing of its outlines is seen to be a separate field, the contrast 

 disappears. Since, then, the judgment of the spatial position, the 

 material independence, of the object in question is decisive for the 

 determination of its color, it follows that the contrast-color arises not 

 through an act of sensation but through an act of judgment." f 



In short, the apparent change in color or brightness 

 through contrast is due to no change in excitation of the 

 organ, to no change in sensation ; but in consequence of a 

 false judgment the unchanged sensation is wrongly inter- 

 preted, and thus leads to a changed perception of the bright- 

 ness or color. 



In opposition to this theory has been developed one 

 which attempts to explain all cases of contrast as depend- 



* Loc. cit. p 408. 

 f Loc. cit. p. 406. 



