January 29, 1886.] 



SCIENCE. 



107 



progress to be able now to give in a popular 

 dress an account of its aims, its problems, its 

 methods, and its results. It is fortunate that 

 Professor Wundt, whose name perhaps, more than 

 that of any other person, has become associated 

 with this modern movement, has given his time 

 to a more or less popular exposition 1 of a few 

 departments of this diffuse subject. The devel- 

 opment of experimental psychology has been such 

 a rapid one, that already one must be a specialist 

 in one department of it. To some extent Pro- 

 fessor Wundt has confined his essays to an ac- 

 count of work done in his own laboratory, while 

 another portion of the book presents views upon 

 those general problems, interesting to every gen- 

 eration of mankind, which seem to him most 

 adequate and scientific. 



In an essay on the problems of experimental 

 psychology, he contrasts the method of this sci- 

 ence with that of metaphysics, with which it is 

 historically closely connected, and defends it from 

 the attacks and prejudices of its opponents. On 

 the one hand, the metaphysicians raise the cry 

 that it is only ' crude empiricism,' a mere atten- 

 tion to natural phenomena, a lower field of work, 

 perhaps good enough for those who are willing 

 to enroll themselves in such a cause ; while the 

 nobler, higher flights of pure philosophy, where 

 every problem finds its solution worked out with 

 a wonderful ease and regularity, are widely open 

 to him. On the other hand, the exact scientists 

 regard this new aspirant for a place amongst the 

 sciences with a suspicious distrust of the justness 

 of its claim. The best answer to the first is to 

 prove to him that many of the problems discussed, 

 pro and con, by various metaphysical schools, 

 can be brought into the laboratory and solved 

 there with the aid of suitably devised apparatus. 

 The answer to the latter will be a demonstration 

 that within natural limits the same regularity 

 and predictability that characterizes his own 

 work, also holds in experimental psychology. 

 In other words, it is the ' measurement of psychic 

 processes' (the subject of the next essay) that 

 forms one of the main problems. 



The beginning of all culture is a clock. Where 

 the conditions of life are so primitive that a time 

 standard is unnecessary, there can be little mental 

 development. For measuring time, man need not 

 invent an apparatus, but has only to learn to tell 

 time on the world-clock, the movements of the 

 heavenly bodies. But it is to be noted that time, 

 though objectively measured, is really a psychic 

 process ; for our perception of time is not changed 

 when the clock stops, but is changed when we fall 

 asleep. One by one the measurements of physical 

 1 Essays. By W. Wundt. Leipzig, Engelmann, 1885. 



phenomena are required, and last comes the utili- 

 zation of these physical measurements for measur- 

 ing the psychic processes. The first time sense is 

 the flow of sense impressions ; the last step is to 

 turn back and measure these impressions. Some 

 sort of philosophy or psychology appears early in 

 history ; then come the great advances of physics ; 

 in the last stage, a psycho-physics. 



Perhaps it is only a coincidence that it really 

 was a branch of physical science, astronomy, that 

 performed the first experiment which led to the long 

 series of studies of psychic time. Even a martyr 

 can be pointed out in this cause ; for it is told that 

 an observer at Greenwich, whose observations 

 were unusually slow, w T as often boxed on the ears 

 for this peculiarity, and afterwards discharged. 

 Twenty years later Bessel saved the honor of our 

 martyr by pointing out that each person had a 

 ' personal equation ' of his own ; that it took an 

 appreciable time to record an observation after it 

 was made, which time differed in different indi- 

 viduals. If we were asked to press a key as soon 

 as we saw an expected flash of light, it would 

 seem to us that the reaction was instantaneous. 

 But still ordinarily it takes from an eighth to a 

 sixth of a second. About a half to a tenth of a 

 second is taken up in central brain processes, while 

 the rest is used in conducting the impression to 

 and from the brain. If, instead of reacting when 

 we saw the light, it was agreed that the reaction 

 should take place only after the color of the light 

 had been perceived, the additional time necessary 

 for perceiving this color might be called the ' dis- 

 tinction ' time, and would vary from a twentieth to 

 a fiftieth of a second. In this way the time neces- 

 sary for hearing syllables, words, seeing colors, fig- 

 ures, pictures, letters, and so on, and understand- 

 ing them, is open to measurement, and the relative 

 time required for these operations marks their com- 

 plexity. Again : we can agree, that, if you see a 

 blue light, you are to react with the right hand ; 

 if a red, with the left. Here is, first, the time for 

 perceiving a light already measured, then the time 

 to distinguish its blueness or redness, also meas- 

 ured, and then the ' choice ' time necessary for 

 selecting the appropriate hand for the color seen. 

 This last psychic process takes about as long as the 

 ( distinction ' time. Of course, it depends on the 

 number of reactions from which the choice is to 

 be made. If it is one of two, the time would be a 

 tenth of a second ; if one of ten (sey, the ten 

 fingers), the time would be half a second. A 

 rather curious result of these observations is, that 

 it takes almost as long to perceive a single letter as 

 it does to perceive a one- or two-syllable word, 

 which shows that the word is perceived as a 

 whole, not as a combination of letters, — that it is 



