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 carelessness.
 Throughout the test the subject’s responses and reactions
 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) averaged
 1.3 accidents per man.
Those who failed in the test (made 5 or more errors) averaged
 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 highest
 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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