December. 1910. 



KNOWLEDGE. 



503 



the twentv-six women was 138'6 of the same units. 



This amounts to a difference of fifteen units 

 between the average Perseveration of the two se.xes. 

 The standard deviations of the two groups, namely. 

 27'9 and 33'3, having been calculated, it iseasyto sho\\ 

 that the odds in favour of the two groups being 

 significanth- different in Perseveration are 53 to 1 : 

 odds which to most people will be enough to prove 

 it, though there is reason to believe that these odds 

 would be greatlv increased if we had larger numbers. 



We arrive, therefore, at this important conclusion 

 — that the a\'erage Perseveration of Women is 

 signiticantl}- less than that of Men. 



This lower Perseveration of Women we should 

 expect to be associated with the mental characters 

 indicated on our scale, i.e.. we should expect in 

 Women greater quickness of apprehension, tact and 

 presence of mind than in Men. with a diminution of 

 those good qualities w hich are associated with high 

 Perseveration. This. I think, agrees pretty well 

 with general experience. 



S(5me vears ago Miss Thompson made a number of 

 ps\chological tests on men and women stuik-nts in 

 America, and could find, I believe, no significant 

 difference between the mental characters of the two 

 sexes. Perseveration appears to be one of the 

 characters in which there is a real difference. 



COMP.\RISOX OF PERSEVEK.ATIOX OF LiGHT AND 



Dark Haired Persons. 



The next point I endeavoured to determine was 

 whether there was any real difference between the 

 Perseveration of Light and of Dark haired persons. 



Hair colour being a very valuable criterion of Race 

 in northern Europe, we might expect to decide from 

 the results obtained the difference between the 

 characters of the fair .\nglo-Saxon element and the 

 dark Mediterranean element, in the population of the 

 British Isles. 



The hair colours were classified in two categories, 

 namely, light, including fair and light brown : and 

 dark, including dark brown and black. 



I find from my figures that the average Persevera- 

 tion is as follows : — 



Light-haired persons ... 154'5 

 Dark-haired „ ... 150-1 



This suggests that the Anglo-Saxon race has 

 somewhat higher Perseveration than the dark Iberian, 

 or Mediterranean, race, and the mental characters 

 associated with the various degrees of Perse\eration 

 that are to be expected in these races. 



Manv other interesting correlations between the 

 physical and mental characters of man might be 

 worked out from such data as we have collected at 

 the .\nthropometric Bureau : but I await larger 

 numbers before undertaking the labour of further 

 statistical calculations. 



These results, however, as far as they go, are 

 sufficient to show how \'astl\' our knowledge of the 

 laws of the Evolution and the education of man 



would be increased by the collection of extensive 

 statistics of mental as well as physical measurements. 



Perseveratio.n and Colour Blindness. 



It has alreadv been mentioned that when a person 

 is colour blind, his persistence for the colour to 

 which he is blind is always much higher than in 

 persons with normal colour vision. 



Does the presence of colour blindness vitiate the 

 measurement of Perseveration b\- the revolving 

 mirror apparatus ? I think not. The alternative 

 conclusion is, I believe, the correct one, namely, that 

 colour blind persons have always high Perseveration. 



The few cases of known colour blind persons that 

 I have dealt with support this conclusion. 



The following hypothesis also leads to the con- 

 clusion that high Perseveration and colour blindness 

 are both manifestations of the same fundamental 

 property of the neural material of the brain. 



Let us suppose that a nervous current is analogous 

 to an oscillating electric current in a conductor w ith 

 self induction and resistance. When the force 

 which maintains such electric waves ceases, the 

 waves do not immediately cease but persist for a 

 time, depending, inter cilia, upon the resistance. The 

 greater the resistance the quicker the waves die out. 

 or the greater the conductivity the longer they persist. 



The experiments of .Shelford Bidwell show that 

 the persistence of a visual sensation is similar to 

 that of electric waves. He has detected the presence 

 of a series of waves of decreasing amplitude.* 



High Perseveration would appear, therefore, to be 

 analogous to high conductivity in the neural systems. 



The nervous system of the human body may be 

 described generally as consisting of three circuits 

 arranged in parallel. Nervous currents passing 

 through the lowest circuit, at the spinal level, 

 produce no sensation ; those passing through the 

 intermediate circuit produce sensations : and those 

 through the highest circuit produce perceptions. 



If, now. the conductivity of the lowest circuit is so 

 high as to drain off practically the whole of the 

 current from the two higher circuits, there will be 

 neither sensation nor perception produced b}- this 

 particular current, though its amount may be equal, 

 or even greater than currents which do produce 

 sensations. 



.\ccording to this hypothesis, a person would be 

 colour blind to red when the sensation producing 

 circuit was short circuited by the high conductivity 

 of the lowest circuit. 



As the whole nervous material of the body has a 

 common origin in a specific section of the germ, ,ve 

 nia\- suppose that its composition is fairly uniform. 

 High conductivity of one part of the nervous system 

 as indicated by colour blindness, makes it probable 

 that the average conductivity- of the whole nervous 

 system will be high. And it follows from this that 

 persistence or Perseveration generally will be high, 

 with all the consequences on the ultimate mental 

 character w hich I have endeavoured to explain above. 



Curiosities of Light and \'iiion. p. 186. 



