Another subject (Mr. George) called it two sixty-two times and one
thirty-eight times. A third subject (Dr. Hylan) called it two
seventy-seven times and one twenty-three times. At the end of the
series he was told what had been done and he said that most of his
sensations of two were perfectly distinct and he believed that he was
more likely to call what seemed somewhat like two one, than to call
what seemed somewhat like one two. With the fourth subject (Mr.
Dunlap) I was unable to do what I had done with the others. I could
get him to call one two for four or five times, but the idea of two
would not persist through a series of any length. He would call it two
when two points very close together were used. I could bring the knobs
within two or three millimeters of each other and he would report two,
but when only one point was used he would find out after a very few
stimulations were given that it was only one. After I had given up the
attempt I told him what I had been trying to do and he gave what seems
to me a very satisfactory explanation of his own case. He says the
early sensations keep coming up in his mind, and when he feels like
calling a sensation two he remembers how the first sensation felt and
sees that this one is not like that, and hence he calls it one. I pass
now to a brief discussion of what these experiments suggest.

It has long been known that two points near together on the skin are
often perceived as one. It has been held that in order to be felt as
two they must be far enough apart to have a spatial character, and
hence the distance necessary for two points to be perceived has been
called the 'space-threshold.' This threshold is usually determined
either by the method of minimal changes or by the method of right and
wrong cases.

If, in determining a threshold by the method of minimal changes--on