experiment. It showed that the affective tone of the sensation within
the filled space was a most important factor in producing an illusory
judgment of distance.

The overestimation of these filled spaces is evidently due in a large
measure to æsthetic motives. The space that is filled with agreeable
sensations is judged shorter than one which is filled with
disagreeable sensations. In other words, the illusions in judgments on
cutaneous space are not so much dependent on the quality of sensations
that we get from the outer world through these channels, as from the
amount of inner activity that we set over against these bare
sense-perceptions.

I have already spoken of the defects of this method of measuring off
equivalent distances as a means of getting at the quantitative amount
of the illusion. The results that have come to light thus far have,
however, amply justified the method. I had no difficulty, however, in
adapting my apparatus to the other way of getting the judgments. I had
a short curved piece of wire inserted in the handle, which could be
held across the line traversed, and thus the end of the open space
could be marked out. Different lengths were presented to the subject
as before, but now the subject passed his finger in a uniform motion
over the spaces, after which he pronounced the judgment 'greater,'
'equal,' or 'less.' The general result of these experiments was not
different from those already given. The short, filled spaces were
overestimated, while the longer ones were underestimated. The only
difference was found to be that now the transition from one direction
to the other was at a more distant point. It was, of course, more
difficult to convert these qualitative results into a quantitative
determination of the illusion.