Subject _R_, 100. Subject _P_, 105. L E S d L E S d SSS 32 56 12 + 20 SSS 16 67 22 - 9 WWW 11 53 36 - 25 WWW 19 72 14 + 5 SSW 6 27 67 - 61 SSW 17 56 32 - 15 WWS 57 36 7 + 50 WWS 37 61 7 + 30 WSS 10 45 45 - 35 WSS 9 69 27 - 18 SWW 3 31 66 - 63 SWW 3 64 33 - 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 - 38 + 5 + 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. TABLE X. _ST_ = 3.0 secs. = _CT_. Subject _Mm._ Subject _A._ Subject _D._