AURAL PERCEPTION BY THE BLIND MEZES AND HILGARTNER. 3 
trials were made on the grounds of the Institute. The original intention 
was to discover with what accuracy the three hoards could he distin- 
guished, but on this point our notes are too incomplete to he of any 
value. A few times a hoard was placed on its side, giving a height of 
two feet, but the records are too few and do not appear in the table; 
they would have increased the percentage of error. In the trials, 
a board was placed as noiselessly as possible at a distance of from 
about 8 to 25 feet from the subject, and the latter was started and left 
to walk alone toward it. Occasionally no board was set up, when the 
subject was stopped after walking 30 feet or so, in cases where he had 
no illusory perception, for that sometimes happened. In a few trials a 
convenient tree was substituted for the boards. By varying the distance 
of the boards, by occasionally picking up a board once set down, or 
another board near it, by using trees after the subject lost his orientation 
by reason of many turnings, and by other devices, we sought to minimize 
any error due to the slight noise of setting up the boards. In this we 
believe our success was complete. 
Some of the remarks made by subjects during the course of the ex- 
periments will make the table plainer. 
C. H. S. says: “I can get around better in clear than in damp weath- 
er/' “I can’t do so well in muddy weather,” the latter in answer to a 
question. 
A. G., his ears being closed, passed from the bright sunlight into the 
shade; on being questioned, he said he felt as if he was running into 
something, as was besides indicated by the abruptness of his halt. The 
remark is interesting from him (vide table). 
P. D., probably the most intelligent subject, when asked how he 
could tell of the presence of the board, said: “It seems as if I tell it by 
my face, but I have heard of that theory [Levy’s; P. D. is a University 
student, taking psychology], and that may have given me the idea.” 
After some remarks about the part played by hearing, but without fur- 
ther questioning, he said : “Often, when I am not sure, I snap my fingers 
or scrape my foot on the ground; then I can tell.” Asked how he came 
to do this, said: “I don’t know; don’t remember beginning it.” 
E. M. says: “A board don’t look as dark as a tree,” but he mistook 
boards for trees, and vice versa, several times. 
All say that when there are noises their perception is materially inter- 
fered with, especially when the noises are of different kinds. “Can’t get 
around so well then.” When carts were lumbering by in the street 40 
feet away, and when there was piano playing or loud singing, the sub- 
jects looked annoyed and confused, and often asked us to wait till the 
disturbance was over. 
