I am happy to say that since the preceding paragraphs (and the notes thereto appertaining) were written, Wundt has himself become converted to the view which I defend. He now admits that in the shortest reactions "there is neither apperception nor will, but that they are merely brain-reflexes due to practice." * The means of his conversion are certain experiments performed in his laboratory by Herr L. Lange, † who was led to distinguish between two ways of setting the attention in reacting on a signal, and who found that they gave very different time-results. In the 'extreme sensorial' way, as Lange calls it, of reacting, minimum winking-time' is then 0.0471 (ibid. 531), whilst his reduced reaction-time is 0.0828 (ibid. vII. 637). These figures have really no scientific value beyond that of showing, according to Exner's own belief (vII. 531), that reaction-time and reflex-time measure processes of essentially the same order. His description, moreover, of the process is an excellent description of a reflex act. "Every one," says he, "who makes reaction-time experiments for the first time is surprised to find how little he is master of his own movements, so soon as it becomes a question of executing them with a maximum of speed. Not only does their energy lie, as it were, outside the field of choice, but even the time in which the movement occurs depends only partly upon ourselves. We jerk our arm, and we can afterwards tell with astonishing precision whether we have jerked it quicker or slower than another time, although we have no power to jerk it exactly at the wished-for moment."-Wundt himself admits that when we await a strong signal with tense preparation there is no consciousness of any duality of 'apperception' and motor response; the two are continuous (Physiol. Psych., II. 226).—Mr. Cattell's view is identical with the one I defend. “I think," he says, "that if the processes of perception and willing are present at all they are very rudimentary. . . . The subject, by a voluntary effort [before the signal comes], puts the lines of communication between the centre for " the stimulus "and the centre for the co-ordination of motions. . . in a state of unstable equilibrium. When, therefore, a nervous impulse reaches the" former centre, "it causes brain-changes in two directions; an impulse moves along to the cortex and calls forth there a perception corresponding to the stimulus, while at the same time an impulse follows a line of small resist. ance to the centre for the co-ordination of motions, and the proper nervous impulse, already prepared and waiting for the signal, is sent from the centre to the muscle of the hand. When the reaction has often been made the entire cerebral process becomes automatic, the impulse of itself takes the well-travelled way to the motor centre, and releases the motor impulse." (Mind, xı. 232–3.)-Finally, Prof. Lipps has, in his elaborate way (Grundtatsachen, 179–188), made mince-meat of the view that stage 8 involves either conscious perception of conscious will.

* Physiol. Psych., 3d edition (1887), vol. 11. p. 266. + Philosophische Studien, vol. iv. p. 479 (1888).

6

one keeps one's mind as intent as possible upon the expected signal, and 'purposely avoids' * thinking of the movement to be executed; in the 'extreme muscular' way one 'does not think at all'† of the signal, but stands as ready as possible for the movement. The muscular reactions are much shorter than the sensorial ones, the average difference being in the neighborhood of a tenth of a second. Wundt accordingly calls them 'shortened reactions' and, with Lange, admits them to be mere reflexes; whilst the sensorial reactions he calls complete,' and holds to his original conception as far as they are concerned. The facts, however, do not seem to me to warrant even this amount of fidelity to the original Wundtian position. When we begin to react in the 'extreme sensorial' way, Lange says that we get times so very long that they must be rejected from the count as non-typical. "Only after the reacter has succeeded by repeated and conscientious practice in bringing about an extremely precise co-ordination of his voluntary impulse with his sense-impression do we get times which can be regarded as typical sensorial reaction-times." Now it seems to me that these excessive and 'untypical' times are probably the real' complete times,' the only ones in which distinct processes of actual perception and volition occur (see above, pp. 88-9). The typical sensorial time which is attained by practice is probably another sort of reflex, less perfect than the reflexes prepared by straining one's attention towards the movement. § The times are much more variable in the sensorial way than in the muscular. The several muscular reactions differ little from each other. Only in them does the phenomenon occur of reacting on a false signal, or of reacting before the signal. Times intermediate between these two types occur according as the attention fails to turn itself exclusively to one of the extremes. It is obvious that Herr Lange's distinction between the two types of reaction is a highly important one, and that the extreme muscular

+ Loc. cit. p. 487.

* Loc. cit. p. 488. Loc. cit. p. 489. Lange has an interesting hypothesis as to the brain-process concerned In the latter, for which I can only refer to his essay.

method,' giving both the shortest times and the most constant ones, ought to be aimed at in all comparative investigations. Herr Lange's own muscular time averaged 0.123; his sensorial time, 0".230.

These reaction-time experiments are then in no sense measurements of the swiftness of thought. Only when we complicate them is there a chance for anything like an intellectual operation to occur. They may be complicated in various ways. The reaction may be withheld until the signal has consciously awakened a distinct idea (Wundt's discrimination-time, association-time) and then performed. Or there may be a variety of possible signals, each with a different reaction assigned to it, and the reacter may be uncertain which one he is about to receive. The reaction would then hardly seem to occur without a preliminary recognition and choice. We shall see, however, in the appropriate chapters, that the discrimination and choice involved in such a reaction are widely different from the intellectual operations of which we are ordinarily conscious under those names. Meanwhile the simple reactiontime remains as the starting point of all these superinduced complications. It is the fundamental physiological constant in all time-measurements. As such, its own variations have an interest, and must be briefly passed in review.*

The reaction-time varies with the individual and his age. An individual may have it particularly long in respect of signals of one sense (Buccola, p. 147), but not of others. Old and uncultivated people have it long (nearly a second, in an old pauper observed by Exner, Pflüger's Archiv, vII. 612-4). Children have it long (half a second, Herzen in Buccola, p. 152).

Practice shortens it to a quantity which is for each individual a minimum beyond which no farther reduction can be made. The aforesaid old pauper's time was, after much practice, reduced to 0.1866 sec. (loc. cit. p. 626).

*The reader who wishes to know more about the matter will find a most faithful compilation of all that has been done, together with much original matter, in G. Buccola's 'Legge del Tempo,' etc. See also chapter XVI of Wundt's Physiol. Psychology; Exner in Hermann's Hdbch., Bd. 2, Thl. I. pp. 252-280; also Ribot's Contemp. Germ. Psych.. chap. VIII.

Fatigue lengthens it.

Concentration of attention shortens it. Details will be given in the chapter on Attention.

*

The nature of the signal makes it vary. Wundt writes: "I found that the reaction-time for impressions on the skin with electric stimulus is less than for true touch-sensations, as the following averages show:

"I here bring together the averages which have been obtained by some other observers :

66

66

..0.213

Thermic reactions have been lately measured by A. Goldscheider and by Vintschgau (1887), who find them slower than reactions from touch. That from heat especially is very slow, more so than from cold, the differences (according to Goldscheider) depending on the nerve-terminations in the skin.

Gustatory reactions were measured by Vintschgau. They differed according to the substances used, running up to half a second as a maximum when identification took place. The mere perception of the presence of the substance on the tongue varied from 0".159 to 0.219 (Pflüger's Archiv, XIV. 529).

Olfactory reactions have been studied by Vintschgau,

*The nature of the movement also seems to make it vary. Mr. B. I. Gilman and I reacted to the same signal by simply raising our hand, and again by carrying our hand towards our back. The moment registered was always that at which the hand broke an electric contact in starting to move. But it started one or two hundredths of a second later when the more extensive movement was the one to be made. Orchansky, on the other hand, experimenting on contractions of the masseter muscle, found (Archiv f. (Anat. u.) Physiol., 1889, p. 187) that the greater the amplitude of contraction intended, the shorter grew the time of reaction. He explains this by the fact that a more ample contraction makes a greater appeal to the attention, and that this shortens the times.

+Physiol. Psych., 11. 223.

Buccola, and Beaunis. They are slow, averaging about half a second (cf. Beaunis, Recherches exp. sur l'Activité Cérébrale, 1884, p. 49 ff.).

It will be observed that sound is more promptly reacted on than either sight or touch. Taste and smell are slower than either. One individual, who reacted to touch upon the tip of the tongue in 0".125, took 0.993 to react upon the taste of quinine applied to the same spot. In another, upon the base of the tongue, the reaction to touch being 0'.141, that to sugar was 0.552 (Vintschgau, quoted by Buccola, p. 103). Buccola found the reaction to odors to vary from 0.334 to 0′′.681, according to the perfume used and the individual.

The intensity of the signal makes a difference. The intenser the stimulus the shorter the time. Herzen (Grundlinien einer allgem. Psychophysiologie, p. 101) compared the reaction from a corn on the toe with that from the skin of the hand of the same subject. The two places were stimulated simultaneously, and the subject tried to react simultaneously with both hand and foot, but the foot always went quickest. When the sound skin of the foot was touched instead of the corn, it was the hand which always reacted first. Wundt tries to show that when the signal is made barely perceptible, the time is probably the same in all the senses, namely, about 0.332′′ (Physiol. Psych., 2d ed., II. 224).

Where the signal is of touch, the place to which it is applied makes a difference in the resultant reaction-time. G. S. Hall and V. Kries found (Archiv f. Anat. u. Physiol., 1879) that when the finger-tip was the place the reaction was shorter than when the middle of the upper arm was used, in spite of the greater length of nerve-trunk to be traversed in the latter case. This discovery invalidates the measurements of the rapidity of transmission of the current in human nerves, for they are all based on the method of comparing reaction-times from places near the root and near the extremity of a limb. The same observers found that signals seen by the periphery of the retina gave longer times than the same signals seen by direct vision.

The season makes a difference, the time being some hun