I want now to indicate how the prolonged interview throws much light on personality development, and lends itself to consideration from the point of view outlined here. If the analyst is “insulted” by the subject in the course of a day’s interview, the subject may the next day report somatic trouble, or morbid reveries, or unusual kindliness toward an annoying person, or a burst of creative work. The interviewer, taking such facts in juxtaposition to others, may be able to predict the kind of substitutive reactions which this person is likely to show in a whole range of social situations, and to predict retrospectively the form of reaction which was manifested at different levels of development. The trained psychoanalyst watches the subject like a hawk for clues of this kind; the possibility of removing his “hunches” from the realm of art into the area of dependable knowledge depends upon the objectification of his observations, and upon the development of specifically experimental methods. A method by which some certainty is to be introduced in personality records is by testing the coincidence of observations taken through time by observers who occupy specified positions in relation to the subject. Very important applications of this procedure have been made to child study by several child psychologists, more particularly by Florence Goodenough and Dorothy Thomas. A set of categories were set up to describe various acts, such as “smiling,” “physical contact with other child,” and “physical contact with object.” The definiteness of each term was then tested by having two independent observers make the same number of observations at fixed intervals during a prescribed period. The results showed which categories were ambiguous, and which categories were sufficiently clear to justify their inclusion in behavior studies. It was discovered, for example, that “smiling” behavior showed much less definiteness than “physical contact with another child.” This procedure makes it possible to measure the error of a measuring procedure and is strictly comparable to the calibrating process common to the physical sciences in determining the relative reliability of measurements made by a particular instrument. The social scientist is compelled to rely on the use of his eyes, and the problem is to standardize the use so that objective results can be secured.[66] Such methods of devising and testing categories for the observation of behavior need urgently to be developed for the study of courtroom, legislative, committee, mass meeting, and other types of behavior in situations of immediate political interest. It is possible to record the differential reactions of participants, and to distinguish that which is inherent in the rôle performed (chairman), and that which is the individualized penumbra of the act (individual gesture).