The Avoidance Of Fatigue

Against the validity of intelligence tests it is often argued that the result

of an examination depends a great deal on the time of day when it is made, whether

in the morning hours when the mind is at its best, or in the afternoon when it is

supposedly fatigued. Although no very extensive investigation has been made of this

influence, there is no evidence that the ordinary fatigue incident to

school work injures the child's per
ormance appreciably. Our tests of

1000 children showed no inferiority of results secured from 1 to 4 P.M.,

as compared with tests made from 9 to 12 A.M.

An explanation for this is not hard to find. Although school work causes

fatigue, in the sense that a part of the child's available supply of

mental energy is used up, there is always a reserve of energy sufficient

to carry the child through a thirty-to fifty-minute test. The fact that

the required tasks are novel and interesting to a high degree insures

that the reserve energy will really be brought into play. This

principle, of course, has its natural limits. The examiner would avoid

testing a child who was exhausted either from work or play, or a child

who was noticeably sleepy.