re no refusals to reach for
anything exposed within reaching distance (10 inches)--other
attractive objects being kept away--shows two things; (1) the very
fine estimation visually of the distance represented by the
arm-length; and (2) the great uniformity at this age of the phenomenon
of Motor Suggestion upon which this method of child study is based,
and which is referred to again below. In respect to the first point,
it will be remembered that the child does not begin to reach for
anything that it sees until about the fourth or sixth week; so it is
evident at what a remarkably fast rate those obscure factors of size,
perspective, light and shade, etc., which signify distance to the eye,
become associated with arm movements of reaching. This method, applied
with proper precautions, obviates many of the difficulties of the
others. There are certain requirements of proper procedure, however,
which should never be neglected by any one who experiments with young
children.

In the first place, the child is peculiarly susceptible to the appeals
of change, novelty, chance, or happy suggestion; and often the failure
to respond to a stimulus is due to distraction or to discomfort rather
than to lack of intrinsic interest. Again, fatigue is a matter of
considerable importance. In respect to fatigue, I should say that the
first signs of restlessness, or arbitrary loss of interest, in a
series of stimulations, is sufficient warning, and all attempts at
further experimenting should cease. Often the child is in a state of
indisposition, of trifling nervous irritability, etc.; this should be
detected beforehand, and then nothing should be undertaken. No series
longer than three trials should be attempted without changing the
child's position, resting its attention with a song, or a game, etc.,
and thus leading it fresh to its task again. Furthermore, no single
stimulus, as a colour, should be twice repeated without a change to
some other, since the child's eagerness or alertness is somewhat
satisfied by the first effort, and a new thing is necessary to bring
him out to full exercise again. After each effort or two the child
should be given the object reached for to hold or play with for a
moment; otherwise he grows to apprehend that the whole affair is a
case of "Tantalus." In all these matters very much depends upon the
knowledge and care of the experimenter, and his ability to keep the
child in a normal condition of pleasurable m