January 17, 1919J 



SCIENCE 



59 



of schooling having its significance in this case 

 chiefly indirectly as evidence of the possession 

 of the abilities measured by the test. The 

 correlation of the test score, independent of 

 schooling, with success in the ground school 

 was about .4. The correlation of amount of 

 scl'.ooling, independent of the test, with success 

 in the ground school, was less than .2. Amount 

 of schooling is thus shown to be useful rather 

 as a rough symptom of breeding, social status 

 and viewpoint than as an index of intellect. 

 That is better measured by a systematic test. 



It coidd be affirmed a priori that the score in 

 the test of mental alertness would not select 

 against success in ability at flying itself, gen- 

 eral fitness to be an officer, or success in actual 

 warfare over the lines. But it might be that, 

 if very accurately prophetic symptoms of these 

 were eH hand, they should be used pure, undi- 

 luted by mental alertness. 



Consequently the significance of the test 

 score for these was determined and compared 

 with other symptoms. To make a short story 

 out of a long and laborious inquiry, it was 

 found that the test score correlated positively 

 (about .3) with ability to learn to fly, and also 

 with general officer-quality. Had the war 

 lasted its correlation with success at the front 

 would have been determined. It was also 

 shown that dilution of a more valuable symp- 

 tom by the test score was in all probability im- 

 possible, since the test score retained a positive 

 partial correlation, independent of such more 

 valuable symptom. Thus, although what we 

 may call athletic mechanical ability (as in 

 sailing a boat, riding a horse or motor-cycle, 

 or shooting) sems to correlate much more 

 closely with ability to fly well, than does the 

 test score, a properly weighted composite of 

 the two correlates still more closely. The 

 same will hold of a composite with courage, 

 or with nervous stability. So the test score 

 may be used as an aid in selection for fitness 

 for one of the four requirements, without fear 

 of selecting the less fit for any other one of 

 the four. 



Almost as soon as the training of reser\-e 

 military aviators began, in June and July, 

 1917, Burtt, Troland and Miles at Cambridge, 



and Stratton at San Diego, began a tryout of 

 tests such as their consideration of the re- 

 actions involved led them to think might be 

 prophetic of success in learning to fly. Later 

 the writer investigated the physical, personal, 

 educational and athletic records of men re- 

 ported as superior and inferior by the flying 

 schools as far as such reports were obtainable. 

 Cooperation of the Committee on Classification 

 of Personnel in the Army with the Personnel 

 and Training Sections of the Division of 

 Military Aeronautics, secured the detail of Dr. 

 Henmon and Dr. Stratton in April, 1918, to 

 study this problem further with a hundred 

 men who learned to fly easily, a hundred men 

 who learned to fly slowly or poorly, or not at 

 all, and a hundred men taken for a test 

 prophecy. It had already become apparent 

 that no one trait of body or mind was clearly 

 and closely correlated with success in flying — 

 that a large number of factors were involved, 

 so that a series of tests each properly weighted, 

 must be combined to give a prophecy close 

 enough to be of practical value. This series 

 was made available for forty-five of the "un- 

 lalo^vns " and a prophecy submitted to the 

 effect that five of these cadets would show as 

 many discharges or transfers for inability to 

 learn to fly as all the other forty. This 

 prophecy was verified and provision was made 

 by the army for continued research along these 

 lines under Captain Stratton, and for four 

 special examining units imder the direction 

 of Captain Henmon to apply the tests to can- 

 didates for cadetships on a flying status. 



In the spring and summer of 1918 Eno, 

 aided by Fry, had been working on an ap- 

 paratus to mimic to some extent the reactions 

 involved in pointing a plane quickly and ac- 

 curately at a target and to record these re- 

 actions in a precise and usable form. Dunlap 

 had developed a systematic test of the changes 

 produced by oxygen-want in an individual's 

 ability in a complex sensory-motor perform- 

 ance somewhat equal in difficulty to the work 

 of a man in combat flying. This was adopted 

 as a regular feature of the differential test of 

 a flyer's ability to withstand oxygen-want in 



