THE SPATIAL CONCEPTION OF THE BLIND. 
BY F. J. DOHMEN, PH. D. # 
In this paper it is not my intention to give an exhaustive psycho- 
logical investigation, but rather a rough summary of facts noted by 
various writers, which I shall supplement with observations drawn 
from my own experience. 
At the outset it is necessary to define somewhat minutely the class 
of individuals to which the discussion applies. The term blind is not 
so simple as might be thought without reflection. In the first place 
there are many gradations of blindness, from that which merely takes 
away the power of reading by sight to that which is total. Obviously 
those blind persons who are able still to distinguish spatial relations 
by sight will not be proper subjects for investigation here, as they 
will always rely chiefly on this remnant of sight for their space per- 
ceptions and conceptions. On the other hand, blind persons not 
hereby excluded must be distinguished according as they were born 
blind, or at least lost their sight in early years, or at an age, when 
the visual conception of space was so well developed as to be retained 
in a considerable measure. Some writers place this lower limit at 
four years, others at about six to seven. In my own case it is six, and 
I am pretty well convinced that I retain no visual ideas of space re- 
lations. To be sure, the most satisfactory study is to be made with 
those born blind, or who lost sight within perhaps the first year of 
life. 
After this introduction we must turn to the perceptions which give 
spatial ideas. The most elementary of these is touch. Indeed, many 
older writers maintained that all spatial perception was built upon 
it. The present view seems to be that sight is able to develop space 
ideas alone, indeed that it is preeminent. This view is taken by 
James Muensterberg, and Wundt, also by Theodor Heller in a set 
of three articles published in 1895 in Yol. XI of the Philosophische 
Studien, entitled Studien zur Blinden-Psychologie, which is an ex- 
tensive treatise on the psychology of the blind. Some have extended 
the same view to the sense of hearing. 
Be this as it may, it is obvious that a considerable difference exists 
between the space-perception of the normal individual and that of 
the blind person. The faculty of sight, once developed, has a wide 
^Honorary Lecturer in Mathematics, The University of Texas. 
