American psychiatrists and psychologists have long been close colleagues and fierce rivals. There is no better illustration of this polarized relationship than the chronic tug-of-war over psychotherapy. Both groups laid claim to psychotherapy-whatever it was and however it was practiced. Psychiatrists attempted to monopolize psychotherapy despite its ambiguous status as an essential component of the healing arts. After the war, psychologists pressed for a share on the basis of their qualifications and competence, but struggled to overcome the limitations imposed by medical envy. This story lays bare the crucial function of tools and techniques for defining the identity and the boundaries of a science-based profession.

The Minnesota Multiphasic Personality Inventory (MMPI) was constructed at the University of Minnesota before and during World War II. In its developmental phase, the MMPI was conceputalized as an efficient way of detecting psychiatric disturbance. The test's construction was made possible by atypical cooperation between psychologists and psychiatrists, within the context of a crisis in the U.S. public mental health care system. The MMPI was designed to meet the diagnostic needs of psychiatrists. As such, it represented the operationalization of medical hegemony. However, the interpretation of the MMPI shifted significantly after the war, reflecting organizational reform in clinical psychology and changing professional relationships between psychologists and psychiatrists.

When a strange new test of perceptual style called the Rorschach reached the New World in the 1920s, it became almost immediately popular. Developed as a psychoana lytic "X ray" of the psyche, it succeeded because American psychologists wanted and needed it to do so, and to do so as that kind of test. Over a decade later, the MMPI was constructed as a more orthodox personality inventory geared to traditional psychiatric categories While this medical legacy was soon removed or obscured, success was more gradual. After the war, clinical psychologists adopted a professional identity independent of psychiatry. Their personality assessment tools, and what counted as success, came to reflect a reclaimed disciplinary genealogy. Standardized mappings and rule-by-numbers tended to displace a trust in experience and expert Judgment. In this context, "proper" Rorschach use came to be seen as indulgent or sadly mistaken. Supporters of the MMPI were, in contrast, able to claim both science and efficiency on their side and colonized the field. The history of these tests clearly illustrates the process of co-production, of how the right tool can become very wrong as networks dissipate and professional time goes by.

Psychological tests, especially the Minnesota Multiphasic Personality Inventory, became the center of public controversy and Congressional scrutiny during the 1960s. This unwanted attention actually helped American psychologists more than they imagined. Assisted by those on Capital Hill, psychologists were able to defend their science in a manner that avoided imposed forms of public accountability. Social questions were reformulated as technical problems. The need to adjust intelligence and aptitude tests reinforced psychologists' control over them. Conversely, personality tests were not made more transparent and nonintrusive, unless psychologists thought these changes were scientifically necessary. This episode prompted tighter regulation of test use and demonstrated that traditional forms of testing were far too important to popularize and "give away".

This journal recently drew attention to an extensive body of highly questionable research published by Hans J. Eysenck in collaboration with Ronald Grossarth-Maticek. The subsequent enquiry by King’s College London concluded that 26 publications were unsafe and warranted retraction. However, the enquiry reviewed only a subset of the 61 questionable publications initially submitted to them, only those Eysenck co-authored with Grossarth-Maticek. The enquiry excluded publications where Eysenck was the sole author. The King’s College London enquiry must be properly completed. They have a pressing responsibility to re-convene and broaden their review to include all Eysenck’s publications based on the same body of research – including an additional 27 publications recently uncovered. The unsatisfactory nature of the KCL review process makes the case for a National Research Integrity Ombudsperson even stronger.