232 THE DISCOVERY OF THE CHILD
are deaf-mutes and defectives, and that attempt which was made
much later through the work of the Germans, Fechner and Weber
and then Wundt, to subject psychology to experimental research
made by means of instruments and measurements.
Itard, who lived about the time of the French Revolution,
was led by his scientific studies on diseases of the ear to experi-
ment the education on a positive basis, looking for reactions which,
by exciting the senses systematically, would stimulate attention and
awaken intelligence and motor activity. The objects which he had
in mind had therefore the real meaning of stimuli.
Later, Fechner, Weber and Wundt tried to found a psycho-
logy on experimental basis, beginning by testing the sensitivity
which existed in normal individuals in respect of minimum stimuli;
aiming at determining with mathematical exactitude what times of
reaction to the stimuli were displayed by the various subjects which
were acted on. Importance was given to the objects by the
possibility of their being more or less directly a means of measure-
ment. They formed the instrumentarium of estesiometry, the
measurement of sensibility.
The two lines of research, born independently, were carried
on independently, the first creating, as it expanded, schools for
deaf-mutes and mental defectives, the second founding institutes
-of estesiometry which had for their purpose experimental research
directed to the building up a new science.
All these research workers, however, seeing that they based
the construction of their instruments on the sensitive reactions of
the man, arrived at a determination of objects for the most part
analogous and similar to one another, although they would con-
stitute in the one case material for the education of the senses and
in the other a kind of arsenal for psycho-sensational measure-
The aim of the two lines of research, so much alike in the
matter of their constructive bases, is therefore quite opposite.
As a matter of fact, estesiometry is seeking for the smallest
stimuli perceptible to a man already fully developed or to a child