
SECTION II., 1883. RSS) Trans. Roy. Soc. CANADA. 
A Problem in Visual Perception. 
By Tue Rey. J. CLARK Murray, LL.D. 
(Read May 23, 1883.) 
The psychology of vision has received invaluable assistance from the recorded cases of 
of persons born blind, who have been cured by the resources of modern surgery. In the 
present paper I propose to notice merely one fact, which has been almost universally over- 
looked, in the mental experience of the patients in some of these cases. The most 
important of these cases—certainly those most accessible to an English reader—are 
reported in the Philosophical Transactions. 1 shall quote from the first and the last cases, as 
these bring out most definitely the phenomenon in question. 
The first case, and the one most frequently cited, is that of a boy born with a cataract 
of unusually opaque quality. He was about fourteen years of age when the cataract was 
removed by Cheselden first from one eye, and afterwards from the other. The report of the 
case is given in the Philosophical Transactions for 1728; and the following is the passage to 
which special reference will be made :—“ At first he could bear but very little light, and 
the things he saw he thought extremely large ; but upon seeing things larger, those first 
seen he conceived less...... And now lately couched of his other eye, he says that objects at 
first appeared large to this eye, but not so large as they did at first to the other; and look- 
ing upon the same object with both eyes, he thought it looked about twice as large as 
with the first couched eye only, but not double that we could any ways discover.” 
The other case to be cited is also that of a young man, four years older than 
Cheselden’s patient at the time of his cure. The surgeon in this case was Dr. Franz, of 
Leipsic, who reports his observations and experiments in the Philosophical Transactions for 
1841. The passage, describing the apparent magnification of visible objects at first is shorter 
than in the previous report, but is equally explicit. “He saw everything much larger than 
he had supposed from the idea obtained by the sense of touch. Moving, and especially 
living objects, such as men, horses, &c., appeared to him very large.” * 
Here, then, is an illusory appearance of magnitude, which, like many ancther 
apparently abnormal phenomenon, may throw light on the normal processes of intelligence. 
From the superior accuracy, which generally pervades Dr. Franz’s report, we may fairly 
take it as conveying the most exact description of the illusion experienced on the restora- 
tion of sight. Now, that description contrasts the idea of magnitude formed by the newly 
recovered sense with that already obtained from the sense of touch. We are therefore 
referred to the conceptions of magnitude which this sense imparts for an explanation of 

* One can scarcely avoid recalling a well-known trait in the narrative of Mark’s Gospel (VIII. 24) :—“T behold 
men, for I see (them) walking as trees.” Whatever may be made of the narrative by modern criticism, it 
undoubtedly implies the belief that newly restored sight would give but imperfect ideas of size, 
Sec. IL, 1883. 12. 
