Introduced nearly 80 years ago, the Minnesota Multiphasic Personality Inventory (MMPI) continues to be one of the most widely used psychological tests in the world. The test, which requires participants to answer a set of true-false questions designed to measure potential symptoms of mental illness or personality disorder, has been used by mental health professionals, substance abuse programs, schools and public safety employers, among others.
Over the decades, the MMPI has undergone three major revisions, but in many ways has remained quite similar to the original test, which was developed by two University of Minnesota faculty members, Starke Hathaway, a clinical psychologist; and J.C. McKinley, head of the university’s neuropsychiatry department.
This past fall, the University of Minnesota Press published the MMPI-3, the first full revision of the test in more than 30 years. The goal of the update was to refresh the MMPIs contents in order to ensure accuracy and effectiveness for a modern population and to keep up with developments in the field of psychology. The update is a major, years-long project: The research team discussed ways to add and rephrase test questions, and then set out to collect sample data from more than 16,000 people in mental health, medical care, forensic and public safety settings as well as 8,000 college students. An additional 3,400 individuals were tested for the purpose of developing new norms for the MMPI-3.
I wanted to find out more about the MMPI’s history and the significance of this latest revision, so I spoke with two experts with deep knowledge about the test and its history, Yossef Ben-Porath, professor of psychological sciences at Kent State University and one of the leaders of the test’s latest revision; and Katie Nickerson, test division manager at the University of Minnesota Press.
Why did Hathaway and McKinley create the MMPI?
Ben-Porath, who worked on the first major revision (known as the MMPI-2) in the late 1980s while earning his Ph.D. at the University of Minnesota, knows a lot about the test’s history.
He explained that Hathaway, then a relatively new staff psychologist, collaborated with McKinley, an established member of the university faculty: “They wanted to create a psychological test that they could give to patients at the hospital to get a direct indication of their diagnosis.”
The MMPI’s signature series of true-false questions, Ben-Porath said, was a means of gathering information in a relatively quick and straightforward manner. During the test, subjects are presented with a series of statements (as many as 567 in the first revision) and are asked to indicate whether the statements are true or false about themselves. The answers are then measured against a set gathered from a control group of subjects without known psychiatric diagnoses.
The test was designed to be a relatively quick and straightforward tool for making psychiatric diagnoses, Ben-Porath said.
How were members of the original control group recruited?
To recruit members of the original control group, Hathaway and McKinley turned to the resources they had at hand, Ben-Porath said.
“They administered the same list of statements to a group of people they approached in the hallways of the hospital and asked if they’d volunteer for a psychology study. The subjects were mainly friends and family members of the patients.”
Because the visitors interviewed had similar backgrounds to the hospital’s patient population, Ben-Porath explained that they made a good control group the purposes of the original study. But as the demographics of the state and the nation began to shift, this frozen-in-time control group didn’t hold up.
For decades, Ben-Porath said, “The MMPI results compared the person who just took the test with those friendly Minnesotans who had been approached in the hallways of the university and volunteered to take part in the study.” As the test gained popularity around the United States and the world, he added, “it became clear that the normative sample needed to be updated.”
The first significant revision of the test was released in 1989, 46 years after its initial publication.
What was the goal of the 1989 revision?
The main goal, Ben-Porath said, “was to update the normative group and to gather a new nationally representative sample throughout the U.S.” The project, which was conducted over the course of the 1980s, was extensive, with the idea of creating a test that better represented the national population.
A committee of psychologists was assembled to update the instrument, Ben-Porath explained. A major contributor to the project was Auke Tellegen, one of Ben-Porath’s mentors and now a professor emeritus of psychology at the U of M.
In the end, the MMPI-2, while a significant change from the first version, still held on to many of the key elements of its predecessor, Ben-Porath said.
The new test relied on the same clinical scales as the original had while introducing a limited number of new items. This strategy was based in practicality, Ben-Porath explained: “There was a lot of continuity on purpose between the original MMPI and MMPI-2. They wanted to be able to use the same code types and rely on the same clinical findings.”
The next revision of the test came less than 20 years later. Why was that?
As practitioners familiarized themselves with the MMPI-2, it became clear that their reliance on the test’s original clinical scales highlighted a pressing need for a significant overhaul, Ben-Porath said.
“One of the problems was that scores on the scale were highly correlated with each other, more than you’d expect. For example, the scales that were developed to identify patients with schizophrenia and those with anxiety disorder were highly correlated with each other — more than those disorders actually co-occur.” There was concern that these similarities could, in a worst-case scenario, lead to misdiagnosis or inappropriate treatment, so leaders in the field began the arduous task of creating another version.
“While we were developing those restructured clinical scales, it became clear to us that to us that the entire instrument would benefit from restructuring,” Ben-Porath said. That realization led to the next major update of the test, which was called MMPI-2-RF, he added: “The RF stood for ‘restructured form.’”
The MMPI-2-RF was released in 2008. This move, while significant, was an example of the pace at which the test has adapted to better represent the general population and to meet its needs.
“It’s been an evolutionary, not a revolutionary process,” Ben-Porath said.
What are some of the biggest changes in this latest revision of the test?
Nickerson said that changes in the MMPI-3 were centered around “the desire that this widely used test continues to be accurate and effective. Collecting new empirically validated data for the MMPI-3 was a critical part for the MMPI to keep up to date and continue to be a standard for assessment worldwide.”
The new version of the test builds on the foundation of the MMPI-2-RF, while updating the more than three-decade-old norms that were collected in the 1980s, Ben-Porath said. The world has changed, he added, and in order to stay relevant, the test must reflect those changes.
“The best way to illustrate the importance of those changes is the fact that not a single member the normative sample for the MMPI-2 had ever heard of the internet. That’s impossible to imagine now, but it was the reality then.”
To guarantee that the test’s normative sample accurately reflected the makeup of the current population, Ben-Porath explained that researchers created a target testing sample based on U.S. Census Bureau estimates of 2020 census results.
Those numbers represent a significant change: “The percentage of individuals who identify as white went from 81 percent in 1980 to 62 percent in 2020,” Ben-Porath said. The other large demographic shift is the proportion of individuals who identify as being of Hispanic origin. “That was around 4 or 5 percent in 1980 and is now over 16 percent projected for the 2020 census.”
In addition, norms for a Spanish-language version of the test were collected to allow for assessment of individuals of Hispanic origin in Spanish.
Another significant change in the test’s administration is the way gender identity of test takers is recorded.
“In the past, in order to score an MMPI you had to indicate whether the individual was male or female,” Ben-Porath said. “We no longer require that. You don’t have to say male or female. You can indicate ‘other,’ or you cannot respond at all. It is not a required response.”
What are some of the more unexpected ways this test is used?
In the decades since its introduction, the MMPI has grown into a tool that is respected by professionals in many fields. No longer only considered for assessment of patients in hospital psychiatry units, it has, over the decades, been used by psychologists in medical settings to determine a patient’s suitability for certain medical procedures.
“We have developed reports specific to spine surgery candidates,” Nickerson said. “These days, candidates for spinal surgery have to have the test be administered before they are approved to undergo the surgery. They use it as a way to ensure that they are good candidates for a successful outcome.” The test is also administered before bariatric procedures like gastric bypass.
Is the release of the MMPI-3 a significant achievement?
Nickerson said this new version of the test is big news in the field of psychology.
“The MMPI-3 is really the first full revision of the test since the late 1980s. It features a new nationally representative sample. The standards have been significantly updated to acknowledge our changing world. What just happened here was a major product launch.”
Changes to this test, which for decades has been considered the gold standard in psychological testing, have significant impact on the field, she continued: “It was a big project that involved some of the major researchers and practitioners in the field.”