Narrator: Imagine being seven months pregnant, deep in a dusty archive, when you realize you’re being watched. This isn't a spy novel; it was the experience of author Merve Emre. While researching the origins of the world's most popular personality quiz, she found files disappearing and an employee from the staid Educational Testing Service (ETS) tweeting about her: "Today I’m creeping on a pregnant lady as part of my job." This bizarre and unsettling welcome was her first clue that the story of the Myers-Briggs Type Indicator (MBTI) was far more than a simple history of a psychological tool. It was a story shrouded in secrecy, driven by obsession, and protected with the fervor of a religion. In her book, Speaking Type, Emre uncovers this hidden history, revealing how a test with no scientific validity came to define how millions of people understand themselves.

Narrator: The story of the MBTI doesn't start in a sterile psychology lab, but in the home of a brilliant and obsessive mother, Katharine Cook Briggs. Born in the late 19th century, Katharine was raised in a household torn between her father's scientific belief in evolution and her mother's devout Christianity. This conflict led her to reject impersonal science and instead focus on the cultivation of personality as a path to personal salvation.

When Katharine had her own daughter, Isabel, her home transformed into what she called a "cosmic laboratory of baby training." She meticulously documented Isabel's development, designing experiments to shape her into a perfectly "civilized" adult. Her "obedience-curiosity" training involved drills and stories meant to instill discipline and ambition, which she believed were essential for finding one's specialized role in society. This early work reveals the core belief that would later define the MBTI: that every person has an innate set of preferences, and the key to a meaningful life is to identify and live in accordance with them, rather than trying to change one's fundamental nature.

Narrator: Katharine's "laboratory" work eventually led her to the writings of Carl Jung. In 1923, after falling into a deep depression, she discovered Jung's book Psychological Types. For Katharine, it was a revelation. She felt Jung had given a scientific language to the ideas she had been developing for years. She abandoned her own theories and spent the next five years obsessively studying Jung, seeing his work as her new "Bible." She began creating tools to make his complex ideas accessible, culminating in a 1926 magazine article titled "Meet Yourself: How to Use the Personality Paint Box," which was the first attempt to bring type theory to the masses.

However, it was her daughter, Isabel Briggs Myers, who transformed these theories into a practical tool. While Katharine was the theorist, Isabel was the pragmatist. During World War II, Isabel saw a need to help people, especially women entering the workforce, find jobs that suited their personalities. Using her own family as a testing ground, she began crafting a simple, forced-choice questionnaire. She simplified Jung's dense concepts—like introversion, extraversion, thinking, and feeling—into straightforward questions that anyone could answer. This was the birth of the indicator, a tool designed not to pathologize, but to empower individuals with self-knowledge.

Narrator: While Katharine and Isabel were developing their intuitive, home-brewed system, a more formal, "scientific" approach to personality was emerging in institutions like Harvard and the U.S. government. At the Harvard Psychological Clinic, Henry Murray was developing "personology," a comprehensive approach to understanding the whole person. Unlike the Briggs women, Murray was concerned with the political implications of personality.

During World War II, this concern became a matter of national security. The Office of Strategic Services (OSS), the precursor to the CIA, commissioned Murray to create a psychological profile of Adolf Hitler. The goal was to understand his motivations, predict his behavior, and devise propaganda to undermine him. Murray's analysis portrayed Hitler as a man possessed, an incarnation of the German people's unspoken needs. This project marked a pivotal moment when personality assessment was no longer just for self-discovery; it had become a political weapon. This trend continued at places like Station S, a secret OSS assessment center where recruits were put through elaborate theatrical exercises—like a staged murder mystery—to see if they had the psychological makeup to be a perfect spy.

Narrator: After the war, personality testing exploded into the corporate world. In an era of "People's Capitalism," companies sought to create a loyal, content, and productive workforce. Isabel Myers found a home for her indicator at the consulting firm of Edward N. Hay, where she used it to help companies match workers to jobs. The indicator was presented as a humane tool for finding the right fit, but it also served the corporate goal of creating the "Organization Man"—an employee who was perfectly aligned with the company's values.

Critics like William H. Whyte argued that these tests were not about personality but about conformity. He even published a guide on "how to cheat" on them, advising people to give the most mediocre, conventional answers to avoid being flagged as a non-conformist. Isabel's indicator, with its positive, non-judgmental language, stood out. It promised not to screen people out, but to help them understand their unique strengths, making it an appealing tool for both managers and employees in the new service economy.

Narrator: In 1956, Isabel began a collaboration with the powerful Educational Testing Service (ETS) to validate her indicator and give it scientific legitimacy. This partnership, however, was fraught with conflict. The male-dominated staff of psychometricians at ETS were deeply skeptical of Isabel, a woman with no formal training in psychology. They dismissed her work as unscientific and referred to her in private letters as "that horrible woman."

The central conflict was with a young statistician named Lawrence Stricker, who conducted studies that found the MBTI to be statistically unreliable. For example, he found that up to 50% of people get a different result when retaking the test just a few weeks later. Isabel fiercely defended her work, arguing that the indicator's value was in the "eating of the pudding"—its practical ability to help people—not in cold statistics. But for the scientists at ETS, belief was not enough. After years of financial losses and frustrating debates, ETS dropped the indicator, leaving its future in doubt.

Narrator: Just as the MBTI seemed destined for obscurity, it was saved by what seemed like a series of meaningful coincidences, or what Jung would call "synchronicity." A clinical psychologist from Florida named Mary McCaulley stumbled upon the indicator in a catalog and became a passionate advocate. She believed it was a powerful tool for helping people, not for diagnosing what was wrong with them.

McCaulley connected with Isabel, and the two formed a powerful partnership. After ETS severed ties, they found a new home for the indicator at a small West Coast publisher, Consulting Psychologists Press (CPP). In 1975, an ailing Isabel signed her creation over to CPP, which began marketing it aggressively. They shortened the questionnaire and softened the type descriptions, making it even more accessible. The MBTI exploded in popularity, becoming a multi-million dollar global business and a cultural touchstone for a new generation seeking self-understanding.

Narrator: Today, the MBTI is everywhere, from corporate team-building retreats to online dating profiles. The certification process to administer the official test is a lucrative industry, attracting a wide range of "true believers"—from executives and life coaches to astrologists. As Emre discovered when she attended a session herself, the training is designed to convince participants that type can explain nearly every facet of human interaction.

Despite its well-documented scientific flaws, the MBTI endures because it functions as a powerful "technology of the self." It provides a simple, self-affirming narrative that helps people make sense of their complex lives. It offers a language to justify who they are, why they make certain choices, and how they relate to others. In a world that often feels chaotic and uncertain, the MBTI provides a framework for identity, a sense of belonging, and a promise of a more rational, ordered existence.

Narrator: The single most important takeaway from Speaking Type is that the power of the Myers-Briggs Type Indicator has never been about scientific truth. Its incredible endurance comes from its power as a story—a compelling, accessible, and deeply personal narrative that allows individuals to feel understood. It gives people a vocabulary for their inner lives and a sense of belonging to a tribe of like-minded others.

The book challenges us to consider a fascinating paradox: how did a tool created in a "cosmic laboratory" by an untrained mother-daughter duo, a tool with no empirical validity, become so deeply woven into the fabric of our culture? Its journey from a home experiment to a global corporate standard reveals less about the science of personality and more about our collective, unending search for who we are and our place in the world.