themselves.

In order to explain the fact that a person sometimes fails to
distinguish between one point and two points near together, it has
been suggested that the sensations fuse. This, I suppose, means either
that the peripheral processes coalesce and go to the center as a
single neural process, or that the process produced by each stimulus
goes separately to the brain and there the two set up a single
activity. Somewhat definite 'sensory circles,' even, were once
believed in.

If the only fact we had to explain was that two points are often
thought to be one when they are near together, 'fusion' might be a
good hypothesis, but we have other facts to consider. If this one is
explained by fusion, then the mistaking of one point for two must be
due to diffusion of sensations. Even that might be admissible if the
_Vexirfehler_ were the only phenomenon of this class which we met. But
it is also true that several contacts are often judged to be more than
they actually are, and that hypothesis will not explain why certain
arrangements of the stimulating objects are more likely to bring about
that result than others. Still more conclusive evidence against
fusion, it seems to me, is found in the fact that two points, one on
each hand, may be perceived as one when the hands are brought
together. Another argument against fusion is the fact that two points
pressed lightly may be perceived as one, and when the pressure is
increased they are perceived as two. Strong pressures should fuse
better than weak ones, and therefore fusion would imply the opposite
results. Brückner[1] has found that two sensations, each too weak to
be perceived by itself, may be perceived when the two are given
simultaneously and sufficiently near together. This reënforcement of