Position in Series.     Percentage Values. 
Ratios.              I  II   III  IV       I    II   III    IV
1.000 :  1.000       0   0    0    0       0     0     0     0
1.000 :  0.874       4   4    4    7      40    40    40    70
1.000 :  0.777       6   6    8   10      60    60    80   100
1.000 :  0.700       6   6   10   10      60    60   100   100
1.000 :  0.636       6   6   10   10      60    60   100   100

In the five horizontal rows on the left of the table are set down the number of times, out of a total of ten judgments, the interval in question was perceived to be greater than the like interval in other groups, under the original relation of uniformity and for the four successive increments.  On the right these numbers are given as percentages of the whole number of judgments.  These figures show an increase of discriminative sensibility for such changes as the series advances.  The percentage of correct discrimination, as it stands in the table, is the same for the first and second positions in the line, but this coincidence is to be attributed to accident, in consequence of the relatively small number of judgments on which the results are based, rather than to a functional indifference in the two positions.  I conclude that fuller experiments would show a curve of continuous increase in the number of correct judgments for the whole series of measures here included.  If we number the series of ratios given above from one to five, the thresholds of perceptible change for this series of positions, expressed in terms of this numerical series, would be:  I., 4.1; II., 4.1; III., 3.9; IV., 3.6.

Secondly, in a series of five trochaic measures, the intervals separating the groups—­which in this case follow the unaccented beat—­were successively lengthened by increments identical with those employed in the preceding set of experiments.  The results are presented in the table below, arranged similarly to the previous one.

TABLE LIX.

Position in Series.          Percentage Values. 
Ratios.              I  II   III  IV         I     II     III    IV
1.000 :  1.000       0   0    0    0        0.0   10.0    0.0    0.0
1.000 :  0.874       1   1    3    4       16.5   16.5   50.0   60.0
1.000 :  0.777       4   4    5    6       66.0   66.0   83.0  100.0
1.000 :  0.700       6   6    6    6      100.0  100.0  100.0  100.0
1.000 :  0.636       6   6    6    6      100.0  100.0  100.0  100.0

These results are essentially identical with those of the preceding section.  The sensitiveness to small differences in duration within the rhythmical series becomes continuously greater as that series proceeds.  The thresholds of perceptible change in terms of the numerical series of ratios (as in preceding paragraph) are as follows:  I., 4.0; II., 4.0; III., 3.7; IV., 3.6.