mingled with the elements from the moving member, and influence the judgment."[18] The importance of these sensations of inner origin was shown in many of the experiments in sections VI. to VIII.  In the instance where the finger-tip was drawn over an open and a filled space, in the filled half the sensations were largely of external origin, while in the open half they were of internal origin.  The result was that the spaces filled with sensations of internal origin were always overestimated.

The failure to recognize the importance of these inwardly initiated sensations is the chief defect in Dresslar’s reasoning.  He has endeavored to make our judgments in the illusion in question depend entirely on the sensations of external origin.  He insists also that the illusion varies according to the variations in quantity of these external sensations.  Now my experiments have shown, I think, very clearly that it is not the numerical or quantitative extent of the objective sensations which disturbs the judgment of distance, but the sensation of inner origin which we set over against these outer sensations.  The piece of plush, because of the disagreeable sensations which it gives, is judged shorter than the space filled with closely crowded tacks.  Dresslar seems to have overlooked entirely the fact that the feelings and emotions can be sources of illusions in the amount of movement, and hence in our judgments of space.  The importance of this element has been pointed out by Muensterberg[19] in his studies of movement.

   [18] Delabarre, E.B., ‘Ueber Bewegungsempfindungen,’ Inaug. 
   Dissert., Freiburg, 1891.

   [19] Muensterberg, H., ‘Beitraege zur Experimentellen Psychol.,’
   Freiburg i.  B., 1892, Heft 4.

Dresslar says again, “The explanations heretofore given, wholly based on the differences in the time the eye uses in passing over the two spaces, must stop short of the real truth.”  My experiments, however, as I have already indicated, go to prove quite the contrary.  In short, I do not think we have any means of distinguishing our tactual judgments of time from our similar judgments of space.  When the subject is asked to measure off equal spaces, he certainly uses time as means, because when he is asked to measure off equal times he registers precisely the same illusion that he makes in his judgments of spatial distances.  The fact that objectively equal times were used by Dresslar in his experiments is no reason for supposing that the subject also regarded these times as equal.  What I have here asserted of active touch is true also of the resting skin.  When a stylus is drawn over the skin, the subject’s answer to the question, How long is the distance? is subject to precisely the same illusion as his answer to the question, How long is the time?