Selects: How Personality Tests Work

Episode Summary

Executive Summary: The episode examines personality tests, especially the Myers-Briggs Type Indicator (MBTI), tracing their roots from ancient humors and Carl Jung to modern corporate use. The hosts explain how these systems aim to categorize people, but criticize their scientific weakness, lack of reproducibility, and misuse in hiring, firing, and legal contexts. They contrast MBTI with more accepted psychometric approaches and discuss the Rorschach and MMPI as other controversial examples.

Main Topics: Historical roots of personality classification: The discussion begins with ancient attempts to map personality, from the four humors to Hippocrates and early temperament theories, showing that categorizing human behavior is not new. Carl Jung and the foundations of modern typologies: Jung’s Psychological Types and his introvert/extrovert ideas are presented as the conceptual base for many modern personality frameworks, including MBTI. MBTI’s development and corporate adoption: The Myers-Briggs Type Indicator is described as a wartime-era adaptation of Jung’s ideas, later commercialized and widely adopted in corporate America for team-building and employee development. Scientific critiques of personality tests: The hosts emphasize major criticisms: self-report bias, categorical over-simplification, poor validity/reliability, and the problem of using type systems to reduce complex personalities to fixed labels. Comparison with more accepted psychometrics: The episode contrasts MBTI with the Big Five and other psychometric approaches that measure traits on spectra and use more rigorous statistical methods. Controversial use of tests in high-stakes settings: The transcript warns against using personality tests in hiring, firing, promotions, criminal justice, and custody cases, where flawed results can have serious consequences. Rorschach and MMPI as related case studies: The Rorschach inkblot test and Minnesota Multiphasic Personality Inventory are used to illustrate broader debates about subjective interpretation, false positives, and the limits of psychological measurement.

Key Arguments: Personality is too complex and situational to be reduced to fixed types; people can display multiple temperaments in the same day. MBTI is based on Jung’s theories and not on robust scientific methods, making it weak as a diagnostic or decision-making tool. Even when a test is called objective, interpretation by humans can reintroduce subjectivity. The Big Five model is more scientifically credible because it treats personality traits as dimensions rather than rigid boxes. Personality tests can be useful for self-reflection or team-building, but not for hiring, firing, or legal judgments. The MMPI and Rorschach show that psychological tests can detect patterns, but they can also over-label healthy people or be overly subjective. Good psychometric instruments attempt to control for bias, faking, and reliability through statistical design and repeated item framing.

Data Points: Corporate adoption of MBTI in the U.S.: 13% of companies - A statistic cited to show how widespread MBTI use is in corporate America. Fortune 100 usage: 89 of the Fortune 100 - Used to illustrate the test’s mainstream popularity among major corporations. British company usage: 10% to 40% - A cited range suggesting MBTI adoption in British companies. MBTI certification cost: $1,500 to $1,600 - Cost to take the four-day training course to become certified to administer the MBTI. Single MBTI administration cost: about $50 - Approximate cost for an individual to take the inventory. Hour of feedback: an extra $100 - Additional fee for one hour of feedback after taking the MBTI. Career report cost: $16.95 - Price for an added career report tied to the MBTI. Rorschach Comprehensive System components: 140 components - The system developed to quantify Rorschach responses. MMPI question count: over 500 questions - The Minnesota Multiphasic Personality Inventory is described as extremely long and exhaustive. MMPI-2 revision year: 2012 - The transcript notes that the MMPI was revised significantly by this time. Rorschach study sample: 100 mentally sound elementary school kids - A study mentioned as producing many false positives for psychosis. Rorschach false positive result: high percentage labeled borderline psychotic - The example is used to show how the test can misclassify healthy people. MBTI categories: 16 types - The inventory sorts people into 16 personality combinations across four dichotomies.

Pivotal Quotes: "The human personality is just too complex, too squishy. Too jelly-like to be boxed into one thing like that." — Chuck Bryant: Core criticism of typology-based personality tests. "It’s just if you put them together, you have just a sketch of somebody’s personality, and you should go much deeper if you're analyzing someone." — Josh Clark: Explaining the more nuanced approach associated with the Big Five. "If you really want real data and science behind it, you have to be able to reproduce it." — Josh Clark: Discussing the scientific requirement of reliability in psychometric testing.

Implications: Listeners should treat personality tests as rough tools for reflection, not objective truth. For workplaces and courts, the episode argues for caution: flawed typologies can distort hiring, evaluation, and justice if taken too literally.