The laboratories being constructed in the early 1900s were critical to the science’s self-definition as well as its legitimacy as a field of intellectual inquiry. Predominant in the new laboratories were the techniques of what was later critically termed brass instrument psychology. These were the methods of experimental introspection where subjects are presented with standard, controlled situations (stimuli) and instructed to give readily quantifiable or classifiable responses. Developed in Germany by Wilhelm Wundt and brought to America by the students who trained with him, introspection set the climate of exacting, controlled, and replicable experiments, ideals that would endure in psychology after the method of introspection itself was abandoned.
Wundt’s version of introspection was intended to uncover the elements of consciousness by observing and recording the dependence of sensory experiences on stimulation varying in intensity, temporal duration, and location. Given the fact that introspection required exacting and immediate (unreflected) responses, subjects were trained to serve as the object of investigation. In fact, psychologists typically served as subjects (called “observers”) in each others’ experiments.
Techniques of introspection were designed to study abstract mental events, ultimately to reveal basic sensation-elements and the laws of their connection. Titchener was the foremost proponent of introspection in America, and during his long career at Cornell University he trained a large number of American students in introspective methods. Despite its strong and rigorous beginnings, introspection did not fare well in America. Not only was the method (and the underlying theory of mental events) inhospitable to practical application, but it did not suit the growing spirit of positivism, a philosophy of science that argued for the exclusive study of observable phenomena and not abstract entities.
At the beginning of the twentieth century, several other methods were being employed by American psychologists. Evolutionary theory had motivated some to develop comparative techniques with which to compare mental abilities of humans and other animals. Unsatisfied by the informal and uncontrolled observations of some evolutionary theorists, Americans such as E. L. Thorndike developed highly controlled laboratory experiments for assessing mental abilities. Thorndike designed experimental “puzzle boxes,” which the animal had to solve in order to escape (and then be fed). The rise of functionalism, a metatheory emphasizing the centrality of mental processes (or functionings) over mental content, invited further developments in methods. With a new interest in functions being propagated via the theories of Dewey and James, psychologists became more interested in the objective observation of responses to stimuli rather than in the mental events associated with those responses. Comparative psychology and functionalism, then, shifted the focus to observable behavior in general and learning in particular. This shift had methodological implications. First, the roles of the experimenter and subject were clearly separated, a role distinction that was to enable distinct assumptions about the mental actions of the experimenters and subjects. In turn, distinct classes of subjects (children, people of color) could be studied. Second, the move toward studying observable behaviors made possible the refinement of objective measures. Finally, the focus on observable behaviors and learning afforded the opportunity to create laboratory analogs to everyday activities: experimenters could devise experimental situations, for instance, which simulated the classroom, labor tasks, or social interactions.
Soon American psychologists came to value an experimental method characterized by scrupulous control of stimulus variables and environmental conditions of the laboratory, precise measurements, and distinct roles of experimenter and subject. Experimentation became the hallmark of the science and the central feature in the training of new psychologists. Notable here is the fact that other methods were used in the early years of the century: survey techniques, observations in natural settings, self-report, case studies, and testing techniques. Although these techniques would continue to be employed, they routinely were perceived as falling short of the objectivity, control, and predictability afforded by laboratory experimentation.