PSYCHOLOGICAL TESTS 
he must come down upon the clutch and foot brake. After each 
movement or response he is told always to come back to his 
original position, but in doing so he must not come down hard 
upon the accelerator. If he does this a mistake is registered. 
The apparatus is so devised that the signal lights are flashed 
automatically and remain lighted for a definite short interval of 
time. In order to be credited with a correct response, the subject 
must react with the appropriate movements within that given 
interval of time. If he makes incorrect movements or reacts too 
slowly, this response is not registered. On the other hand, if he 
is not careful and in his excitement strikes the accelerator, his 
mistake is registered automatically on an electric counter. The 
number of correct responses gives an index of his alertness and 
speed of reaction; the number of errors, a measure of his care- 
lessness. Throughout the test the subject’s responses and reac- 
tions are automatically recorded on electric counters which total 
each type of response separately. All that is necessary at the 
end of a test is to read off the figures from the several electric 
counters. The duration of this test is r 5 minutes (214, pp. 
25-26). 
When tried on the drivers for a cab company in Pittsburgh, 
this test gave the following results. These figures refer to the 
€Iror score, a measure of carelessness (214). 
Those who passed the test (made fewer than 5 errors) aver- 
aged 1.3 accidents per man. 
Those who failed in the test (made 5 or more errors) aver- 
aged 3.0 accidents per man, 
Of those making no errors in the test, 53.0% had accidents. 
Of those making from 1 to 3 errors in the test, 81.2% had 
accidents. 
Of those making 4 or more errors in the test, 87.5% had 
accidents. 
Of those making no errors in the test, 54.6% were rated high- 
est in carefulness by superintendents. 
Of those making from 1 to 3 errors in the test, 31.25% were 
rated highest in carefulness. 
Of those making 4 or more errors in the test, none were rated 
highest in carefulness, 
Figures 7 and 8 are reproduced with the kind permission of 
Popular Science Monthly. 
Dodge’s test for the selection of gun-pointers in the navy 
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