Unaided Observation. --Observation, as the man on the
street uses the term, is, of course, the oldest method known to
science. We make our observations in all natural sciences by
the aid of our sense organs. In one sense instrumentation may
be looked upon merely as a device for increasing the number of
observations which can be made simultaneously. In a normal
individual, vision is the sense most usually employed. When
this sense is denied us, or will not work in a particular problem,
we depend for observation upon the auditory and tactual sense
organs. Under ordinary conditions, smell and taste are not used
as organs of scientific observation. At times, however, their
use is indispensable in chemistry, medicine, etc. Our muscular
sense enables us principally to make observations concerning the
movements and positions of our own bodies, serving at the same
time crudely the purpose of enabling us to react differentially
to the size, weight, and position of objects other than parts of
our own bodies.

Practically all of the results which have been obtained in the
psychology of common-sense have come through the use of un-
aided observation. By such observation we obtain gross changes
in the activities of the individual or the crowd, the general
behavior of children and animals, and certain aspects of emo-
tional and instinctive activity. We must not confuse the ob-
servation made by a scientist without instrumental control with
the amateurish and muddled observation made by the untrained
individual. Some of the finest work we have in biology has been
done by scientists without instrumental control. We cite the
behavior work of Fabre, Wheeler, and the Peckhams. Unaided
observation, however, even when employed by the trained man,
becomes a genuine scientific method only when he puts his results
down and begins to note exceptions, to draw tentative conclusions,
and then to gather new observations to check up such conclusions.
In other words, such data must be subjected to statistical methods
before conclusions can be verified. We brought out in the last
chapter that even without the use of instruments we may learn
something about the stimuli which produce responses in human

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