judgments which seem to be due to fusion or diffusion of sensations.
But they are responsible only in this way, they prevent the correction
of the first impression. I do not mean that a person never changes his
judgment after having once made it, but a change of judgment is not
necessarily a correction. Often it is just the contrary. But where a
wrong judgment is made and cannot be corrected inability to localize
is a prominent factor. This, however, is only a secondary factor in
the perception of number. The cardinal point seems to me the
following:

Any touch sensation, no matter by how many objects it is produced, is
one, and number is an inference based on a temporal series of
sensations. It may be that we can learn by association to infer number
immediately from the quality of a sensation, but that means only that
we recognize the sensation as one we have had before and have found it
convenient to separate into parts and regard one part after the other,
and we remember into how many parts we separated it. This separating
into parts is a time process. What we shall regard as _one_ is a mere
matter of convenience. Continuity sometimes affords a convenient basis
for unity and sometimes it does not. There is no standard of oneness
in the objective world. We separate things as far as convenience or
time permits and then stop and call that _one_ which our own attitude
has determined shall be one.

That we do associate a sensation with whatever idea we have previously
connected it with, even though that idea be that of the number of
objects producing it, is clearly shown by some experiments which I
performed in the laboratory of Columbia University. I took three
little round pieces of wood and set them in the form of a triangle. I
asked the subject to pass his right hand through a screen and told him