The report of each experiment includes a description of the apparatus used, a statement of the method, and a formulation of the results. Since the value of experimental work, and the possibility of comparing one set of results with another depend so largely upon the method, the greatest pains has been taken to secure uniformity, and to describe the method in full in each case. The experiments were all performed by the author, with the exception of a part of the reaction-time tests, which had to be repeated because of a source of error in the apparatus. For these the author is indebted to Dr. W. C. Gore and Mr. H. J. Pearce, of the Graduate School of the University of Chicago.
A few words in general on the methods employed may not be out of place, in spite of the fact that each is described in full in connection with the test. The guiding principle in selecting the method was the desire to make the directions to the subject as clear and simple as possible and at the same time secure the greatest possible accuracy of result. In all the tests on discriminative sensibility this double end seemed best secured by requiring a simple judgment of comparison (i.e., lighter or heavier, more or less cold, etc.) between two stimuli. The subject was told nothing of a standard stimulus, and the order of the standard and stimulus of comparison was varied. The difference in intensity between the standard and the stimulus of comparison was varied until the point was found at which three-fourths of the judgments were correct. In the threshold tests of taste and smell, tasteless and odorless preparations were used to control the threshold illusions. The greatest care was taken to avoid
