hope of success, but also what slight modification or addition and
diminution will more than double the personal power."[10] The true
psychological specialists surely ought to decline this flattering
confidence. Far from the "almost infallible certainty," they can
hardly expect even a moderate amount of success in such directions so
long as specific methods have not been elaborated, and so long as no
way has been shown to make experimental measurements by which such
mere guesswork can be replaced by scientific investigation.

The only modest effort to try a step in this direction toward the
psychological laboratory is recorded by Taylor,[11] who tells of Mr.
S.E. Thompson's work in a bicycle ball factory, where a hundred and
twenty girls were inspecting the balls. They had to place a row of
small polished steel balls on the back of the left hand and while they
were rolled over and over in the crease between two of the fingers
placed together, they were minutely examined in a strong light and the
defective balls were picked out with the aid of a magnet held in the
right hand. The work required the closest attention and concentration.
The girls were working ten and a half hours a day. Mr. Thompson soon
recognized that the quality most needed, beside endurance and
industry, was a quick power of perception accompanied by quick
responsive action. He knew that the psychological laboratory has
developed methods for a very exact measurement of the time needed to
react on an impression with the quickest possible movement; it is
called the reaction time, and is usually measured in thousandths of a
second. He therefore considered it advisable to measure the
reaction-time of the girls, and to eliminate from service all those
who showed a relatively long time between the stimulus and reaction.
This involved laying off many of the most intelligent, hardest-working,
and most trustworthy girls. Yet the effect was the possibility of