In each experiment the observer was allowed to observe as many complications (coincidences of click and letter) as he desired, in order to assure himself of his judgment. The experimenter counted and recorded the number observed in each experiment. Experiments were made in series of ten. Six different combinations of intervals were used in this first group of experiments. The auditory intervals (time between successive clicks) and visual intervals (time between successive members of the visual series) are given at the tops of the columns in Table I. This table is a summary presentation of the results of this group. There were three observers. During each hour of experimentation with a given observer, at least one series with each of the first four time-interval combinations was tried out. "Aver. num. Trials" means the average number of complications observed in the whole number of tests averaged. "Num. Series av." means the number of series of ten experiments each averaged to give the displacement results below. "Aver. Error" is the average of all the displacements of the auditory impression, _irrespective of the direction of the displacement_. "Mean Displacement" is the _actual mean displacement_ as obtained by dividing the algebraic sum of all displacements, positive and negative, by the number of experiments. The plus sign indicates a positive displacement, and the minus sign, a negative. Negative and positive are here used in the sense customary in similar experiments,--namely, the click, being heard as simultaneous with a visual impression which actually came before it, was said to be displaced negatively, and the click, being heard as simultaneous with a visual impression coming in fact later than it did, was said to be displaced positively. Average errors and mean displacements are given in the table in thousandths of seconds. Observers were asked to locate the click in the visual series in terms of one tenth the distance or time between the letters. TABLE I Aud. Interval (sec.) 1.28 2.56 4.04 8.40 1.28 2.02 Vis. Interval (sec.) .040 .080 .120 .260 .080 .120 Obs. B Av. num. Trials 13.9 5.8 3.8 2.1 9.8 13.9 Num. Series av. 8 13 13 8 2 2 Aver. Error (sec.) .056 .064 .077 .164´ .045 .067 Mean Displac'mt (sec.) +.045 -.040 -.067 -.152 +.045 +.067 Bo Av. num. Trials 9.4 4.1 3.0 2.0 5.5 3.5 Num Series av. 6 10 11 8 3 2 Aver. Error. (sec.) .114 .060 .054 .049 .05 .082 Mean Displac'mt (sec.) +.114 +.045 +.033 .000 +.045 +.082