factor of visualization in any of my experiments, and may have
regarded it as a serious omission. It might be offered as a criticism
of my work that the fact that I found the tactual illusions to exist
in the same sense as the optical illusions was perhaps due to the
failure to exclude visualization. All of the subjects declare that
they were unable to shut out the influence of visualizing entirely.
Some of the subjects who were very good visualizers found the habit
especially insistent. I think, however, that not even in these latter
cases does this factor at all vitiate my conclusions.

It will be remembered that the experiments up to this time fall into
two groups, first, those in which the judgments on the cutaneous
distances were reached by direct comparisons of the sensations
themselves; and secondly, those in which the sensations were first
localized and then the judgment of the distance read from these
localizations. Visualizing, therefore, entered very differently into
the two groups. In the first instance all of the judgments were made
with the eyes closed, while all of the localizations were made with
the eyes open. I was uncertain through the whole of the first group of
experiments as to just how much disturbance was being caused in the
estimation of the distance by visualizing. I therefore made a series
of experiments to determine what effect was produced upon the illusion
if in the one set of judgments one purposely visualized and in the
other excluded visualizing as far as possible. In my own case I found
that after some practice I could give very consistent judgments, in
which I felt that I had abstracted from the visualized image of the
arm almost entirely. I did not examine these results until the close
of the series, and then found that the illusion was greater for those
judgments in which visualization was excluded; that is, the filled
space seemed much larger when the judgment was made without the help