believe it would be better not to make this distinction so pronounced.
Here again I have concerned myself primarily with only one illusion,
the illusion which deals with open and filled spaces. This is the
illusion to which Dresslar[12] devoted a considerable portion of his
essay on the 'Psychology of Touch,' and which he erroneously thought
to be the counterpart of the optical illusion for open and filled
spaces. One of the earliest notices of this illusion is that given by
James,[13] who says, "Divide a line on paper into two equal halves,
puncture the extremities, and make punctures all along one of the
halves; then, with the finger-tip on the opposite side of the paper,
follow the line of punctures; the empty half will seem much longer
than the punctured half."

[12] Dresslar, F.B., _Am. Journ. of Psy._, 1894, VI., p. 313.

[13] James, W., 'Principles of Psychology,' New York, 1893,
II., p. 250.

James has given no detailed account of his experiments. He does not
tell us how many tests were made, nor how long the lines were, nor
whether the illusion was the same when the open half was presented
first. Dresslar took these important questions into consideration, and
arrived at a conclusion directly opposite to that of James, namely,
that the filled half of the line appears larger than the open half.
Dresslar's conclusion is, therefore, that sight and touch function
alike. I have already said that I think that Parrish was entirely
right in saying that this is not the analogue of the familiar optical
illusion. Nevertheless, I felt sure that it would be quite worth the
while to make a more extensive study than that which Dresslar has
reported. Others besides James and Dresslar have experimented with