138 



SCIENCE 



[N. S. Vol. XXXVII. No. 943 



4. Selecting from 50 forms, as in Fig. 2, 25 

 forms previously shown and examined for a min- 

 ute or two. The 25 forms are shown in Fig. 3. 



Fig. 1 



5. Marking the necessarily false statements in 

 mixed series of false and true statements, the four 

 trials being of four grades of difficulty. 



a®#OHOOv*i] 



<S)A0*0A^[2]0© 

 C^ASS«A<] ®^A 



Fig. 2 



& o o o 



[E] ^ O O 



^ D 



6. Addition. 



7. Doing what is directed in such instruction- 

 sheets as: 



Cross out the smallest dot . . . 



How many ears has a cat 



Make a line across this line | ., 



etc., etc. 

 and 



With your pencil make a dot over any one of 

 these letters : F G H I J and a comma after the 

 longest of these three words: boy mother girl. 

 Then if Christmas comes in March, make a cross 



right here but if not, pass along to the 



next question and tell where the sun rises 



If you believe that Edison discovered America 

 cross out what you just wrote, etc., etc. 



8. Selecting valid from invalid reasons for a 

 given fact, the four tests being of four grades of 

 difficulty. 



The time required would be approxi- 

 mately two hours, say thirty minutes a day 

 on four days chosen at random. 



Prom the combined score made by an in- 

 dividual in these eight tests, his general in- 

 tellectual ability — his capacity, that is, for 

 science, scholarship and the management of 

 ideas of all sorts — could be prophesied with 

 a surprisingly small error. Suppose that 

 the general intellectual ability of the dull- 

 est men who are able to look after and sup- 

 port themselves (men who though temper- 

 ate and strong earn say $400 a year in 

 good times in New York City) be repre- 

 sented by a and that of Aristotle or Goethe 

 by a + 'h, the difference, b, being 100. Then 

 the amount of such ability assigned by the 

 test alone would not, on the average, vary 

 from the individual's true amount by more 

 than 5 ; and would not vary therefrom by 

 more than 14 in one case out of a hundred. 

 The 5 and 14 are very cautious estimates, 4 

 and 11 being probably nearer what such an 

 experiment would in fact reveal. 



If each of us knew all in the company 

 well and wrote down the names in an order 

 of general intellectual ability, and if all of 

 these orders were combined into an order 

 representing the impartial judgment of the 



