^76 



SCIENCE. 



[Vol. XV. No. 371 



SCIENCE: 



4 WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



PUBLISHED BY 



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NEW YOEK, Mabch 14, 1890. 



CONTENTS: 



Jl New Electric Transfer-Table 169 

 JiSLi. Gardiner O. Hubbard 170 



Notes and News 175 



. Wkntal Science. 



The Rivalry of Mental Impres- 

 sions 176 



Thought and Respiration 177 



Health Matters. 



The Origin ot Fever 177 



European Infantile Mortality 177 



The Pate of Cadaveric Microbes. 177 

 Kecent Saving of Life in Michigan 177 

 Gaetric Juice as a Germicide . . . 177 

 .Sook-Reviews. 

 .Electric Light Installations and 

 the Management of Accumu- 

 lators 178 



A Text-Book on Roofs and 

 Bridges 178 



Elements of Logic as a Science 



of Propositions 178 



Among THE Publishers 179 



Letters to the Editor. 

 Supposed Aboriginal Fish-Weirs 

 in Naaman's Creek, near Clay- 

 mont, Del. Hilborne T. Cresson 181 

 The June Drought in the Rocky 



Mountain Region G. H. Stone 181 

 The Fiske Range-Pinder 



Bradley A. Fiske 182 



Industrial Notes. 

 A New Draughtsman's Protrac- 

 tor 188 



JIENTAL SCIENCE. 



The Rivalry of Mental Impressions. 



Whenever two or more impressions are presented to tlie 

 •mind at the same time, there results a rivalry between them 

 .^n attracting the attention and getting into the focus of con- 

 rsciousness. Usually the attention is divided between them, 

 •though this flitting of the attention is at times so rapid and so 

 unconscious that we hesitate to believe that it has really taken 

 ^lace. If the one process is automatic in character, or nearly 

 ■BO, the interference is reduced to a minimum. When both 

 processes are voluntary, mutual interference is inevitable; and 

 its extent will depend upon the complexity and other charac- 

 teristics of the task, and will doubtless vary, too, with each 

 individual. Some simple experiments in this field by M. Binet, 

 though they hardly do more than open out the possibilities of 

 research in this direction, may be here recounted for their 

 general interest and suggestiveness. The subject of the experi- 

 anent is asked to take hold of a rubber bulb connected by means 

 of a tube with a recording apparatus consisting of a point 

 araised and lowered by the air-pressure within the tube, and 

 writing upon a smoked surface fastened to a rotating drum. 

 He is required to press this bulb once a second, and the result 

 as a tracing on the smoked surface showing very regular curves. 

 With this is compared the tracing produced when at the same 

 Aime be is required to perform some simple mental exercise, 

 such as reading aloud, adding or multiplying numbers, and the 



like. The most usual result is that the intervals between the 

 pressures are lengthened, with some persons only slightly, with 

 others more noticeably ; and in some cases the pressures even cease 

 altogether for a brief period. Very frequently, too, the move- 

 ments are less forcible, so that the curves are not as high as nor- 

 mally. Again, let the subject be told to make a series of five 

 pressures, then allow a second' s interval and begin another series 

 of five; and so on. This is done very constantly and regularly; 

 but, if the subject performs another task at the same time, we 

 have, in addition to the other irregularities, an irregularity in 

 the number of pressures in a series, sometimes only four, and 

 sometimes six. Sometimes the interval is neglected or two 

 pressures overlap, and in every way the mental friction and 

 inco-ordination is shown. Tlie pressure upon the rubber tube, 

 in turn, interferes with the mental task, although this cannot 

 be so accurately noted. The addition of simple numbers takes 

 considerably longer than normally, and the result is often 

 wrong. M. Binet notices, too, that the pressures soon get to 

 be done subconsciously, the subject not knowing at the eud of 

 the experiment whether he has made an error, or has written 

 irregular curves cr not. The pressures thus become more or 

 less unconscious while still remaining voluntary. It is inter- 

 esting to note, that, if the pressure be done by both hands, the 

 eirors and irregularities are the same. If, for example, the one 

 hand presses four times instead of five, while its owner is 

 engaged in some mental task, the left, pressing at the same 

 time, will also write four instead of five curves, thus indicating 

 that one volition brings about both actions. The degree of 

 interference depends upon the nature of the two tasks; and if 

 we keep the one task the same, and vary the other, we have a 

 kind of test of the power of an individual to do two things at 

 once. It was found that some subjects could perform simple 

 additions and keep up a series of two pressures in a second, 

 but not with more than two; others could keep up as many as 

 five in a series. But all these actions are extremely fatiguing, 

 and some individuals refused to go on with them on account of 

 the headaches they are apt to produce. 



A different aspect of this interference is revealed when the 

 two hands attempt to make two different movements at the 

 same time. In all such cases there is great mutual interfer- 

 ence, not alone because the two tasks are closely similar, and 

 so employ allied brain-centres, but especially because the 

 movements of the two hands are subject to a special co-ordina- 

 tion, and their disassociation is proportionately difiicult. If 

 one hand attempts to draw curves and the other straight lines, 

 the curves will be somewhat straightened out, and the straight 

 lines somewhat curved. If the one hand is to beat two beats 

 to every five of the other, this may be done correctly for a time, 

 but soon the two tend to beat the same number of times. If 

 one hand attempts to write a sentence while the other draws 

 circles, the writing and the circles will both materially suffer. 

 All this when the two tasks are different: if the two hands 

 make the same movement, they seem to aid each other, and 

 especially does the preferred hand (right or left handedness) 

 help the other. 



M. Binet has studied another phase of the subject, introducing 

 us to a quite different order of mental phenomena. If the atten- 

 tion, instead of being divided between the operations, is sharply 

 concentrated upon one, we approach the case in which a person 

 abstractedly does one thing while his attention is devoted to 

 another, — an artificial absent-mindedness, which, as usual, 

 implies an extreme "present-mindedness" in another direc- 

 tion. The subject is given something to read, and his one hand 

 he is told not to consider at all. If the attention be sufficiently 

 engrossed (and this can be done with only a few subjects), the 

 hand will reproduce slight movements imparted to it by the 

 operator in total unconsciousness of their origin. Such move- 

 ments are spoken of as automatic movements. These are of a 

 quite different character from the foregoing; for while there 

 the two acts interfered with each other, and the more so the 

 less intense the effort to produce them both, here the two acts 

 do not interfere with each other, and are best performed when 

 no conscious effort at all is made. This difference M. Binet 



