ON MENTAL AND MUSCULAR FATIGUE. 295 



In this report I have endeavoured to make it plain that experi- 

 mental fatigue is just such an experimental modification as facilitates a 

 study of the processes of muscular contraction, and also explain the 

 lines along which this study is being undertaken. The progress of the 

 investigation is not sufficient to warrant any more direct form of 

 statement. 



Interim Report (No. 2). — Mental Fatigue in Schools. June 1910. 

 By Mr. H. Sackville Lawson. 



This investigation, an outline of which was given in a previous 

 report, was begun in November 1908. The experimental part of the 

 work will have been completed by the end of July 19f0. 



The general object has been to discover what relation exists between 

 the proved ability (relative) of a subject and his capacity for continuous 

 work at high pressure; to discover, that is, whether an able boy is more 

 resistant to fatigue than one less gifted. 



The local Committee engaged on this investigation consists of three 

 head-masters of elementary schools and the present writer. The number 

 of boys experimented on is thirty, ten from each of the three schools. 

 Each boy was within two months of nine years on January 1, 1909. 

 The nature of the experimental work has been twofold. It has been 

 the aim of the Committee — 



(1) To obtain, by means of suitable tests submitted, a ' General 

 Intelligence ' Order of Merit for the thirty boys. 



(2) To provide continuous work of such a nature and for such a 

 period of time that fatigue effects may be shown. 



Part I — General Intelligence Order of Merit. 



Twelve tests have been given. The length of time for a single test 

 has been from five to ten days. The Final Order of Merit has been 

 obtained by aggregating the places obtained in the various intelligence 

 tests. This Final Order is considered to be a hierarchy of Natural 

 Intelligence. Incidentally it may be mentioned that a separate order of 

 merit has been obtained by the ordinary scholastic examination methods. 

 This has been found to correlate with the other to the extent of 0'61 

 where 1 = complete similarity of rank or identity of position. 



Pakt II. — Fatigue Tests. 



The general method of procedure has been as follows: — 

 Written work, generally of a mathematical nature, has been given 

 for a period of half an hour per day. This half-hour has been taken 

 either at the beginning or at the end of the school day. On the expira- 

 tion of each five minutes a signal has been given in order that the 

 output per period may be calculated. Thus there have been six con- 

 secutive periods each of five minutes' duration. The output in sums 

 completed per period, as well as the number accurately done, has been 

 calculated. Increase in rapidity and improvement in accuracy have 

 been assumed to be due to the favourable influence of practice, while 

 the reverse result has been ascribed to the inhibiting effects of fatigue. 



