The method of right and wrong cases was used in the next group of experiments, to secure the same conditions of making the judgment in each of the three cases used above. Selecting a letter near the middle of each series, I asked the observer, in each of these cases, just as in that of the single letter, to say whether the click was before, on, or after the letter. I worked _out_, in successive experiments by successive adjustments, from the position of apparent simultaneity of click and letter, in both directions, to a point where in 75% of the cases the click seemed to come before; and also to one where it seemed to come after, in 75% of the cases. So also I worked _in_ both ways, by successive adjustments, from regions of clear discrimination of time-difference and direction, to points where the time-relation was uncertain or wrong in 75% of the trials. By averaging the just perceptible and the just not perceptible, in each case, the thresholds were obtained for "click first" and "click last." The time between these thresholds I call the "range." It is really a measure of James's "specious present" and of Stern's "Präsenzzeit." (An admirable presentation of similar results by Wilhelm Peters[114] has appeared since this work was done.) The best means of comparing these results, for our present purposes, and also of bringing them into relation with the complication-results already obtained, is to take the mean point between these thresholds, and state its position, in time, relative to the time of the visual stimulus (letter) just before or after which the click came. This mean point is called the "Threshold Mean" in the following tables. In Table IV, for example, "After Letter .026 sec." means that the mean point between the thresholds, "click first" and "click last" falls twenty-six sigmas after the time of the exposure of the letter. These results are readily comparable with those of Peters. By dividing the "range" by two, and adding the "threshold mean" to one half, and subtracting it from the other, one has the total interval between "click first" and "click last" and its place with reference to the time of the visual stimulus. TABLE IV _Obs._ _Twelve Letters_ _Three Letters_ _One Letter_ A Threshold Mean After After Letter .026 sec. On Letter .041 sec. Letter .020 sec. Range .093 sec. .062 sec. G Threshold Mean Before Before After Letter .015 sec. Letter .020 sec. Letter .062 sec. Range .072 sec. .083 sec. .304 sec. Sh Threshold Mean Before After After Letter .003 sec. Letter .027 sec. Letter .003 sec. Range .172 sec. .111 sec. .241 sec.