inaccurate for use, and, as Wundt himself admits, * the precise duration of stage 3 must at present be left enveloped with that of the other processes, in the total reaction-time.

My own belief is that no such succession of conscious feelings as Wundt describes takes place during stage 3. It is a process of central excitement and discharge, with which doubtless some feeling coexists, but what feeling we cannot tell, because it is so fugitive and so immediately eclipsed by the more substantive and enduring memory of the impression as it came in, and of the executed movement of response. Feeling of the impression, attention to it, thought of the reaction, volition to react, would, undoubtedly, all be links of the process under other conditions, and would lead to the same reaction-after an indefinitely longer time. But these other conditions are not those of the experiments we are discussing; and it is mythological psychology (of which we shall see many later examples) to conclude that because two mental processes lead to the same result they must be similar in their inward subjective constitution. The feeling of stage 3 is certainly no articulate perception. It can be nothing but the mere sense of a reflex discharge. The reaction whose time is measured is, in short, a reflex action pure and simple, and not a psychic act. A foregoing psychic condition is, it is true, a prerequisite for this reflex action. The preparation of the attention and volition; the expectation of the signal and the readiness of the hand to move, the instant it shall come; the nervous tension in which the subject waits, are all conditions of the formation in him for the time being of a new path or arc of reflex discharge. The tract from the senseorgan which receives the stimulus, into the motor centre which discharges the reaction, is already tingling with premonitory innervation, is raised to such a pitch of heightened irritability by the expectant attention, that the signal is instantaneously sufficient to cause the overflow. No other

* P. 222. Cf. also Richet, Rev. Philos., VI. 395-6.

For instance, if, on the previous day, one had resolved to act on a signal when it should come, and it now came whilst we were engaged in other things, and reminded us of the resolve.

"I need hardly mention that success in these experiments depends in a high degree on our concentration of attention. If inattentive, one gets

tract of the nervous system is, at the moment, in this hairtrigger condition. The consequence is that one sometimes responds to a wrong signal, especially if it be an impression of the same kind with the signal we expect.* But if by chance we are tired, or the signal is unexpectedly weak, and we do not react instantly, but only after an express perception that the signal has come, and an express volition, the time becomes quite disproportionately long (a second or more, according to Exner†), and we feel that the process is in nature altogether different.

In fact, the reaction-time experiments are a case to which we can immediately apply what we have just learned about the summation of stimuli. Expectant attention' is but the subjective name for what objectively is a partial stimulation of a certain pathway, the pathway from the 'centre' for the signal to that for the discharge. In Chapter XI we shall see that all attention involves excitement from within of the tract concerned in feeling the objects to which attention is given. The tract here is the excito-motor are about to be traversed. The signal is but the spark from without which touches off a train already laid. The performance, under these conditions, exactly resembles any reflex action. The only difference is that whilst, in the ordinarily so-called reflex acts, the reflex arc is a permanent result of organic growth, it is here a transient result of previous cerebral conditions.

very discrepant figures.

This concentration of the attention is in the highest degree exhausting. After some experiments in which I was concerned to get results as uniform as possible, I was covered with perspiration and excessively fatigued although I had sat quietly in my chair all the while." (Exner, loc. cit. VII. 618.)

* Wundt, Physiol. Psych., 11. 226.

Pflüger's Archiv, vII. 616.

In short, what M. Delbœuf calls an 'organe adventice.' The reactiontime, moreover, is quite compatible with the reaction itself being of a reflex order. Some reflexes (sneezing, e.g.) are very slow. The only timemeasurement of a reflex act in the human subject with which I am acquainted is Exner's measurement of winking (in Pflüger's Archiv f. d. gesammt. Physiol., Bd. VIII. p. 526, 1874). He found that when the stimulus was a flash of light it took the wink 0.2168 sec. to occur. A strong electric shock to the cornea shortened the time to 0.0578 sec. The ordinary 'reaction-time 'is midway between these values. Exner reduces' his times by eliminating the physiological process of conduction. His reduced

6

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 resistance 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, x1. 232–3.)-Finally, Prof. Lipps has, in his elaborate way (Grundtatsachen, 179–188), made mince-meat of the view that stage 3 involves either conscious perception or conscious will.

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

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. 488.

+ Loc. cit. p. 487.

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. II. pp. 252-280; also Ribot's Contemp. Germ. Psych. chap. VIII.