wealth of material pertaining to adaptive behavior. Its
solid achievements lie in the domain, not of consciousness, but of
instinctive, habitual, and intelligent adaptation. It teaches us little
that has to do unequivocally with consciousness as distinct from things,
but it teaches us much concerning stimulus and response, attention and
habit, conflict and adjustment. The doctrine that psychology is a
science of behavior is justified at least to the extent that it
emphasizes a factor, the importance of which introspectionism has
consistently refused to recognize. Whatever conclusion we may ultimately
reach regarding the nature of consciousness, the whole drift of
psychological and biological investigation seems to indicate that an
adequate conception of consciousness and of the distinctive problem of
psychology can be attained only on the basis of a painstaking reflection
on the facts of behavior.

I

It is evident that the attempt to ascertain the nature of consciousness
and of psychology from the standpoint of behavior is committed to the
assumption that the behavior in question is of a distinctive kind. The
justification of this assumption will enable us to formulate the
definitions which we seek. Discussions of conscious behavior ordinarily
emphasize the similarity between conscious and reflex behavior rather
than the difference. An attitude of expectancy, for example, is usually
conceived as a sort of temporary reflex. Certain nervous connections are
organized for the occasion, so that, when a given stimulus arrives, it
will induce its appropriate response. This situation is best
exemplified, perhaps, in simple reaction-experiments, in which the
subject makes a certain predetermined response upon presentation of the
stimulus. The process is supposed to be of the reflex type throughout,
the only difference being that ordinary reflexes are relatively
permanent and unvarying, whereas a prearranged response to a stimulus
has to do with a reflex that is made to order so as to meet the
exigencies of the moment.

For certain purposes such a description of conscious behavior is no
doubt sufficiently accurate. Our present concern, however, is with the
differences between these temporary organizations and ordinary
reflexes. In order to bring out these differences, let us introduce a
slight complication into our reaction-experiment and suppose that the
subject is to make one of two alternative responses, according to the