In the first instance, sixty series were taken from Subject B, with the conditions the same as in the experiments of Group 1, except that two types of series were taken; the first two stimulations being strong and the third one weak in the first type (SSW), and the order being reversed in the second type (WSS). The results gave values of ET of 5.27 secs. for SSW and 5.9 secs. for WSS.

In order to get comprehensive qualitative results as rapidly as possible, a three-second standard was adopted in the succeeding work and only one compared interval, also three seconds, was given, although the subject was ignorant of that fact—the method being thus similar to that adopted later for the final experiments of Group 2, described above. Six types of tests were given, the order of stimulation in the different types being SSS, WWW, SSW, WWS, SWW and WSS, the subject always knowing which order to expect. For each of the six types one hundred tests were made on one subject and one hundred and five on another, in sets of five tests of each type, the sets being taken in varied order, so that possible contrast effect should be avoided. The results were practically the same, however, in whatever order the sets were taken, no contrast effect being discernible.

The total number of judgments of CT, longer, equal, and shorter, is given in Table VIII. The experiments on each subject consumed a number of experiment hours, scattered through several weeks, but the relative proportions of judgments on different days was in both cases similar to the total proportions.

TABLE VIII.

ST=CT=3.0 SECS.

Subject R, 100. Subject P, 105.
LESdLESd
SSS325612+ 20SSS166722- 9
WWW115336- 25WWW197214+ 5
SSW62767- 61SSW175632- 15
WWS57367+ 50WWS37617+ 30
WSS104545- 35WSS96927- 18
SWW33166- 63SWW36433- 25

By the above table the absolute intensity of the stimulus is clearly shown to be an important factor in determining the constant error of judgment, since in both cases the change from SSS to WWW changed the sign of the constant error, although in opposite directions. But the effect of the relative intensity is more obscure. To discover more readily whether the introduction of a stronger or weaker stimulation promises a definite effect upon the estimation of the interval which precedes or follows it, the results are so arranged in Table IX. that reading downward in any pair shows the effect of a decrease in the intensity of (1) the first, (2) the second, (3) the third, and (4) all three stimulations.

TABLE IX.
Subject R.Subject P.
(1)SSS+ 20- 6
WSS- 35- 55- 18- 12
SWW- 63- 25
WWW- 25- 385+ 30
(2)SSW- 61- 15
SWW- 63- 2- 25+ 10
WSS- 35- 18
WWS+ 50+ 85+ 30- 48
(3)SSS+ 20- 6
SSW- 61- 81- 15- 7
WWS+ 50+ 30
WWW- 25- 75+ 5- 25
(4)SSS+ 20- 6
WWW- 15- 35+ 5+ 11

There seems at first sight to be no uniformity about these results. Decreasing the first stimulation in the first case increases, in the second case diminishes, the comparative length of the first interval. We get a similar result in the decreasing of the second stimulation. In the case of the third stimulation only does the decrease produce a uniform result. If, however, we neglect the first pair of (3), we observe that in the other cases the effect of a difference between the two stimulations is to lengthen the interval which they limit. The fact that both subjects make the same exception is, however, striking and suggestive of doubt. These results were obtained in the first year's work, and to test their validity the experiment was repeated at the beginning of the present year on three subjects, fifty series being taken from each, with the results given in Table X.