Page:Mind (New Series) Volume 12.djvu/65

 ANTAGONISTIC KEACTIONS. 51 The vertical column headed chron. shows the average length of reaction time as determined by the use of the chronoscope, while the column N, preceding it, gives the number of experiments on which in the case of each subject the average is based. In the second section of the table are given the results gained by the graphic method, the number of experiments appearing under N. The column st-r gives the average length of the interval between the presentation of the stimulus and the beginning of the rise of the curve which indicates depression of the finger, while the column r-ap gives the length of the interval between the beginning of rise of the curve and its highest point or apex. 1 The column mv shows in each case the mean variation of the data given in the column immediately preceding. In ana- lysing and measuring the curves it has been assumed that the apex of the antagonistic curve corresponds to the point of time at which the contact of the electric key is broken in reacting by the chronoscopic method. This assumption is perhaps not strictly correct, but if the apex be not chosen it would be difficult to find any other point on the descending curve which can be more certainly and accurately determined. In any case the error must be small. A difficulty meets us also in finding the terminating point in the ordinary form of reaction. I have in this case chosen the point where the curve just begins to show the decided fall indicating the lifting of the finger : the difficulty in determining this point is however greater than in finding the apex in the antagon- istic reaction, since the line of the reaction curve in the interval before the reactive impulse manifests itself is often not level, but undulates more or less owing to variation of pressure or physiological tremor. A similar uncertainty is apt to be found in determining precisely the beginning of the rise in the antagonistic reaction. Such difficulties are inseparable from the use of the graphic method for such purposes. It ma,y be mentioned that the latent time of the notice during the course of the investigation the different natural atti- tudes of the subjects towards the reaction process : for example, of the two demonstrators in a physiological laboratory one found the sensorial reaction ' clumsy,' while the other found it ' easier ' than the muscular reaction. 1( The following table gives the magnitude of the central value or median of the observations recorded in Table I. chron. st-r. r-ap. A -19 -18 -05 B -17 -14 -03 C -18 -13 -04