Subjective Sensations and Illusions. 831 



yellow, on a ground of Hue. Then, opening his eyes on a yellowish 

 wall twenty feet off, the word was seen magnified, and in golden char- 

 acters. The cause of the illusion, as to the colors in such cases, is ex- 

 plained on page 440. The magnified appearance of the word is due to 

 another illusion. When the word was first seen, the visual angle, and 

 the amount of the retinal surface involved, was determined by its dis- 

 tance away, say five feet. When the eye rested on the wall, estimated 

 in a sub-conscious manner to be twenty feet distant, although the 

 visual angle remained the same and the same patch of the retina was 

 concerned in the vision, the letters would appear four times as big each 

 way. The estimate of distance unconsciously goes along with every 

 sight sensation. A man, 100 yards away, does not appear to get larger 

 if he approaches us, although at 20 yards the visual angle is five times 

 as great. 



Abercrombie relates that a friend of his, after bending over a small 

 print of the Virgin and Child and looking at it intensely for some time, 

 raised his head and was startled to see the life-size figure of a female 

 with a child in her arms at the further end of the room. The upper 

 part of the body only was represented, and he at once perceived that the 

 illusion was due to the impression made upon the eye and brain by the 

 picture. The increased size was due to the projection of the image to a 

 distance. The illusion remained distinct for about two minutes, or un- 

 til the parts fatigued by the steady gaze had recovered. 



Dreams almost always consist, in part at least, of illusions. Any im- 

 age which may be aroused is apt to remain for a moment unbalanced 

 and uncontradicted, so that it yields that unquestioned sensation that has 

 the realistic properties belonging to an objective impression. Such il- 

 lusions, as well as waking ones, are often shaped by objective stimula- 

 tions. External stimulations of the senses during sleep often form the 

 initiatory suggestions of dreams. The rays of the moon or sun shining 

 upon the sleeper may suggest images of a glorious, gorgeous nature. 

 But sounds especially are productive of suggestion. M. Alf Maury re- 

 lates l ' that when a pair of tweezers was made to vibrate near his ear, 

 he dreamt of bells, the tocsin, and the events of June, 1848." 



' ' Schemer gives an amusing case of a youth who was permitted to 

 whisper his name into the ear of his obdurate mistress, the consequence 

 of which was that the lady contracted a habit of dreaming about him, 

 which led to felicitous change of feeling on her part. " 



< < The dream illusion of falling down a vast abyss, is plausibly re- 

 ferred by Wundt, to an involuntary extension of the foot of the sleeper. " 



The barking of a dog caused Sully to dream that a dog came and 

 licked his face. ( See Sully 's Illusions.) 



