to fix his attention on the space as it was traversed by the finger.
The results were always the same: the greater the amount of attention,
the longer the distance seemed.

In another experiment, I tried the plan of tapping a bell as the
subject was passing over the filled space and asking him, after he had
measured off the equivalent open space, whether the sound had occurred
in the first half or in the second half of the filled space.

When the finger-tip was drawn over two adjacent open spaces, and
during the first a bell was tapped continuously, this kind of filled
space was underestimated if the distance was long and overestimated if
the distance was short. So, too, if a disagreeable odor was held to
the nostrils while the finger-tip was being drawn over one of the two
adjacent open spaces, the space thus filled by the sensations of smell
followed the law already stated. But if an agreeable perfume was used,
the distance always seemed shorter than when an unpleasant odor was
given.

In all of these experiments with spaces filled by means of other than
tactual sensations, I always compared the judgment on the filled and
open spaces with judgments on two open spaces, in order to guard
against any error due to unsymmetrical, subjective conditions for the
two spaces. It is difficult to have the subject so seat himself before
the apparatus as to avoid the errors arising from tension and flexion.
In one experiment, a piece of plush was used for the filled space and
the finger drawn over it against the nap. This filled space was judged
longer than a piece of silk of equal length. The sensations from the
plush were very unpleasant. One subject said, even, that they made him
shudder. This was of course precisely what was wanted for the