Which research method is used to study the relationships between variables?

Theoretical Assumptions and Methodological Approach

Eysenck advocated and adopted what he saw as the methods characterizing the physical sciences. For Eysenck, human behavior could be studied like any other natural phenomenon. Throughout his career, he searched for laws and regularities that might provide a deeper-level, causative structure for human behavior. He took Thorndike's notion of the primacy of measurement as a starting point—anything psychologically real and scientifically important could and should be made measurable. Without measurement, there could be no hope of precise, testable theory. Eysenck combined the pragmatic, rule-bound operationism of correlational methods with experimental work that utilized the continuous measurement scales and instrumental techniques of the physical sciences.

Eysenck remained suspicious or dismissive of aspects of psychology that did not meet his criteria of good science. His antipathy to psychoanalysis was legendary; it was, he thought, insular and subjective, imprecise and untestable. Those parts of psychoanalysis that could be rendered predictive seldom did so successfully. In short, Freudian psychology was a fiction—made all the more damaging by its widespread influence and uncritical application.

Eysenck believed that humans were clearly biosocial organisms. He rejected any notion of a dualism of mind and body in favor of a continuum. It was an assumption that he felt was “too obvious to require supporting argument” and he seldom gave one. However, he was an interactionist rather than a biological reductionist, consistently arguing that behavior was both biologically and socially determined.

4.2.2 Psychometrics and psychology

Correlation provided also a solution to a problem of contemporary psychophysics, related to education. Gustav Theodor Fechner began applying the methods of error theory to the measurement of sensory discrimination in the mid-nineteenth century. Psychophysics was plagued, however, by the problem that a task—for example, of distinguishing two slightly different weights—could not be repeated indefinitely, because the subject learned over time to do better. Indeed, the left hand acquired some of the fine discrimination developed through practice with the right hand. By the end of the century, this obstacle had become a topic of investigation in its own right, as an approach to the psychology of learning. Systematic use of experimental randomization was developed for studies of this kind (Dehue 1997). They provided also a wide field of application for correlational methods. Did childhood study of dead languages really train the mind for speedier or more thorough learning of other subjects, such as science, history, or literature? The growth of mental testing in the early twentieth century opened another question of correlations. To what extent did students who proved themselves adept in some particular study excel also in others? Charles Spearman's g, or general intelligence, and the ‘intelligence quotient’ or IQ, which flourished in America, presupposed a basic unity of the mental faculties. Psychometricians and educational psychologists developed a body of statistical methods to measure this intelligence, or to decompose it, and to assess the relations of its components (Danziger 1990).

In the 1930s and 1940s, as psychology turned resolutely experimental, quantification became practically mandatory. Once again, educational psychology and parapsychology took the lead in the assimilation of novel methods of experimental design and analysis. The new paradigm of a proper experiment involved a randomized design of control and experimental populations, yielding results that would, in most cases, be subjected to analysis of variance (ANOVA). A worthwhile result was defined in part by a test of significance: the ‘null hypothesis’ that the treatment had no effect should be rejected at some specified level, commonly 0.05 (Gigerenzer et al. 1989).

3 The Postwar Era: ‘Americanization’ and the Alternatives

In the USA, the postwar years saw explosive expansion and differentiation in both the scientific and professional realms. The establishment of a divisional structure within the APA in 1947—already negotiated during the war—reflected this process. Despite the optimism of the time, it proved difficult to subsume all aspects of psychology's protean identity within single university departments or graduate programs. Fragmentation was most obvious in the different research practices institutionalized in experimental, social, and personality psychology.

Cognition returned to the laboratory in this period, supported in part by reliance on methodological conventions patterned on those of the behaviorists, such as rigorous separation of independent and dependent variables, in part by computer-centered models of mental processes. In contrast to the statistical inference techniques and the corresponding computational models of mind that came to be preferred in cognition research, the preferred research tools in educational psychology were the correlational methods pioneered by Galton. A comparable methodological split distinguished neobehavioristic learning theory from experimental social psychology and personality theory. Nonetheless, experimental studies of social influence on perception by Solomon Asch and of prejudice by Gordon Allport, as well as T. W. Adorno and colleagues' The Authoritarian Personality study (1950) captured the imagination of many in the field. The popularity of such studies reflected a widespread tendency of the period to psychologize, and thus individualize, social problems. Meanwhile, developmental psychology took the work of Piaget as a touchstone for numerous studies closely related to the practical needs of schools for age-related developmental norms.

By the 1970s, the sheer numbers of psychologists (over 70,000, over 100,000 by the end of the century) had reached levels that could not have been imagined 50 years earlier. The growth was worldwide, but more than two-thirds of the total were Americans. The openness of both discipline and profession to women continues; today more than half the doctorates in the field go to women. Gender divisions also continue, with women being most numerous in developmental and educational psychology and men in experimental, industrial, and personnel psychology. Nonetheless, the broad institutional anchorage of psychology in the USA was more than sufficient to assure that the research and professional practices instituted there would spread throughout the world, and that alternative viewpoints coming from Asia, Africa, or Latin America would generally be marginalized.

The most important exceptions to the overall trend were the impact of Piaget in developmental psychology, and the reception of work by British psychologists Hans Eysenck and Raymond Catell in personality testing and diagnostics. In cognition research, the work of Bartlett and the achievements of Soviet researchers such as Alexander Luria were mobilized to lend respectability and theoretical sophistication to the resurgent field in the USA. Nonetheless, the all-pervasive influence of computer metaphors and the associated information-processing models were plainly of Anglo-American origin.

The history of the psychological profession after 1945 continued to be affected by contingent local circumstances. The rise of clinical psychology in the USA was originally driven by the need to deal with large numbers of mentally ill veterans after World War II. The new field ultimately brought forth its own basic research in both clinical and academic settings, which led to the emergence of scientific communities based on methodological norms quite different from those of experimental or developmental psychologists. In addition, an eclectic, so-called ‘humanistic’ psychology movement arose in opposition to both behaviorism and psychoanalysis, and became widely popular in psychotherapy, social work, and the emerging field of counseling psychology.

In Europe, the rise of clinical psychology came approximately 10 years later than in the USA. There, in contrast to the USA, the supremacy of personality diagnostics and its quantitative tools had already been established in basic research before the professionalization of the clinical field. Another important difference was that clinical training in academic settings in Europe was based far more on cognitive and behavioral techniques than on psychoanalysis. Barriers to the academic institutionalization of psychoanalytic research and training were surmounted only in exceptional cases.

What had been a predominantly European field at the beginning of the twentieth century has become deeply dependent on US research styles and professional practices. US predominance has been contested by dissident local-language movements, most notably in France and Germany. Most significant, however, is the contrast between US predominance worldwide and the insecure standing of trained psychologists in the USA itself. Vagueness and confusion in the use of the term ‘psychologist’ in public discussion have been remarkably consistent over time; the term itself lacks legal protection in any case. The fact that the popularity of self-help books does not depend on whether their authors are psychologists or not indicates that even in the USA, where most of the world's psychologists live and work, trained academics and professionals can hardly claim hegemony over psychological discourse in the public sphere to the degree that physical scientists can in their fields.

What kind of research method is used to identify relationships between variables?

Which type of research best predicts the relationship between variables?

Which of the following methods provides a relationship between two variables?