laboratory studies with human subjects in conflict situations
are feasible. Some of the findings with animals have already
been corroborated with human beings. In the end, however,
our knowledge of man, though it may start with humbler
organisms, must be rounded out by studying man himself.

Our chapter has been long, but it would have been longer if we
had paid attention to non-experimental studies of motivation, especially
to the work of Sigmund Freud ( 1856-1939) who, more than any other,
is identified with the modern emphasis upon the sexual drive in human
beings. For Freud, this drive was the foundation for his general theory
of psychoanalysis, the basic tenets of which are now available in many
books and articles written for laymen as well as students and profes-
sional psychotherapists. We cannot go into the intricacies of this theory
here. but we may note that many of its concepts (e.g., regression, sym-
bolism, and repression) have found their parallels in experimental re-
search, even at the sub-human level. The future may show that this
development has even more points of contact with behavioral science
than are now apparent.

The best single text on motivation to which we can direct you is
P. T. Young Motivation of behavior ( 1936) which contains an excel-
lent account of the research in this field prior to 1936. Young has
himself made significant experiniental contributions to our knowledge,
especially in studying the sub-hungers.

The distinction between appetites and aversions is an old one, going
back at least to the time of Thomas Hobbes ( 1651). Young, in the book
mentioned above, treats these as two classes of drives, and so does.
E. C. Tolman, in a thought-provoking little book called Drives toward
war ( 1942). Tolman's book, which leans heavily upon observations of
animal behavior, also includes some interesting speculations concerning
the relation of basic motives to several psychoanalytic concepts and to
certain sociological and economic teachings.

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