other optical illusion, is genuinely reversed for touch.


II.


I began my work on the problem in question by attempting to verify
with similar apparatus the results of some of the previous
investigations, in the hope of discovering just where the suspected
error lay. It is unnecessary for me to give in detail the results of
these preliminary series, which were quite in agreement with the
general results of Parrish's experiments. Distances of six centimeters
filled with points varying in number and position were, on the whole,
underestimated in comparison with equal distances without intermediate
point stimulations. So, too, the card with saw-toothed notches was
judged shorter than the card of equal length with all but the end
points cut out.

After this preliminary verification of the previous results, I was
convinced that to pass from these comparatively meager statistics,
gathered under limited conditions in a very special case, to the
general statement that the optical illusion is reversed in the field
of touch, is an altogether unwarranted procedure. When one reads the
summarized conclusions of these previous investigators, one finds it
there assumed or even openly asserted that the objective conditions of
the tactual illusion are precisely the same as those of the optical
illusion. But I contend that it is not the real analogue of the
optical illusion with which these experiments have been concerned.
The objective conditions are not the same in both. Although something
that is very much like the optical illusion is reversed, yet I shall