In its earliest use in the 13th century, “personality” referred to the quality, character or fact of being human. By the 18th century, the word pointed to the traits that made a person a distinctive individual. The 19th and 20th centuries saw the rise of systems designed for the mass classification of human beings, including personality tests. People have been trying to stuff each other into categorical bins for thousands of years. “These ideas go back to the ancient Greeks like Hippocrates and so on,” said Martin Gerlach, a postdoctoral researcher who studies complex systems at Northwestern University.

Today, these tests are more beloved and far-reaching than ever, especially on websites like BuzzFeed and Facebook. These tools and typologies are based on powerful, enduring myths about what personality is and how we can measure it. Here are five.

Myth No. 1: Personality is innate.

To many practitioners of and believers in personality assessment, personality is forged in the “dreamlike chaos” of infancy”, as Katharine Briggs, co-creator of the Myers-Briggs Type Indicator (MBTI), liked to say. “Every one of us is born either an extrovert or an introvert, and remains extrovert or introvert to the end of his days,” she claimed.

1 in 5
Fortune 1000 firms use some form of personality tests

The MBTI or the Enneagram (which classifies people as one of nine personality types) claim that they allow their subjects to discover their “shoes-off selves”, as Briggs’s daughter, Isabel Briggs Myers, referred to the true, immutable and essential you. One of the first and only major studies of personality development concluded that a child’s genetic makeup had a stronger influence on his personality than did his upbringing.

Yet, longitudinal studies have reached different conclusions about when personality becomes fixed: During one’s school years or upon one’s entry into the workforce; at 17 or 21 or 25 or 30. Many of the systems of personality classification we use today (the MBTI, the Big Five, for example) are based on flawed experimental design. Their conclusions were derived by studying subjects — medical students, research scientists or Air Force officers — whose results were not at all generalisable.

There is nothing innate or natural about the way we discuss personality; it is a human invention.

Myth No. 2: Personality assessments are based on the science of psychology and designed by psychologists.

Personality tests are used by psychologists and counsellors. They are taught in psychology, education and business courses, and featured in textbooks.

But some of the most popular personality assessments were produced by amateurs and autodidacts. Take the MBTI. It was created by two American women Katharine Cook Briggs and her daughter Isabel Briggs Myers.

Myers had no formal training in psychology or sociology. They were wives and mothers who believed that their daily domestic labours — managing their households, tending to the emotional needs of their children and husbands — made them especially suited to understanding individual personalities and interpersonal relations. They designed their system of type by poring over Carl Jung’s quasi-mystical opus Psychological Types (1921), biographies of famous men and 19th-century novels, and by deriving questions from their readings that they tested on their family members and friends around their kitchen tables.

Myth No. 3: The questions on personality tests are free of prejudice.

Only 24-61% had same results when they took the same MBTI test multiple times

Personality tests often purport to ask questions that are neutral or unthreatening. The MBTI’s questions, for instance, provide a “positive and neutral ground” from which to address work or relationship problems, promises Naomi Quenk, the author of Essentials of Myers-Briggs Type Indicator Assessment.

At first glance, this seems true. Consider the following two questions: “In your daily work, do you (a) rather enjoy an emergency that makes you work against time; or (b) usually plan your work so you won’t need to work under pressure?”

And: “In planning a trip, would you prefer to (a) most of the time do whatever you feel like that day; or (b) know ahead of time what you’ll be doing most days?”

The MBTI’s publishers say the questions are appropriate for anyone who can read at a seventh-grade level, but that leaves out a huge swathe of the world’s population. Questions are exclusionary in their content and framing. They involve making decisions about what to do at parties (talk to everyone or just one person), how to plan a vacation (ahead of time or at the last minute), or how to succeed at an office job or at school. The scenarios they depict are impenetrably bourgeois; many people may never have the situations, the money or the leisure time or to make these kinds of decisions.

Myth No. 4: Personality assessments are valid and reliable.

Personality tests are sold on the promise that they are valid (they measure what they say they will measure) and reliable (they produce consistent results).

“Many studies over the years have proven the validity of the MBTI instrument,” says the Myers & Briggs Foundation. “Based on results from a nationally representative sample of 1,378 people,” claims the MBTI’s publisher, CPP, the indicator’s “median internal consistency . . . is .77.” (The benchmark for reliability is 0.7.)

Yet, every major personality test has faced challenges to its reliability and validity. Studies show that the personality types are inconsistent and cannot predict career success or other characteristics.

A 1991 study commissioned by the United States National Research Council on the MBTI found that the indicator’s test-retest reliability — whether you got the same results when you took it more than once — fell woefully short of the APA’s reliability benchmarks: Only 24 to 61 per cent of subjects received the same result when they took it multiple times.

Studies show that the personality types are inconsistent and cannot predict career success or other characteristics.

Myth No. 5: Personality tests are harmless fun, like astrology.

They maybe fun, but they need not be so easily dismissed. They are more than a harmless distraction because personality tests are used by powerful institutions to make decisions with far-reaching consequences. One in five Fortune 1000 companies uses some means of personality testing to screen job candidates, both to hire the right type of person and to eliminate unfavourable types.

Because of their widespread use by employers and human resources departments, personality tests have colonised and commodified the individual psyche. They have been used to prop up the idea that, if only we could find the jobs best suited to our personalities — if only we could “love what we do” — then we could bind ourselves to our work freely and gladly. This is tremendously beneficial to employers. It helps launch a “double-barrelled attack upon turnover”, as Myers once said, by persuading people to do their jobs without complaining, without agitating, without dreaming of a better, more equitable or more just workplace — or a world where the workplace is no longer integral to social organisation.

— Washington Post

Merve Emre, an associate professor of English at Oxford University, is the author of The Personality Brokers.

Commonly used personality tests:

Myers-Briggs Type Indicator (MBTI): The gold standard of personality tests is the MBTI, which divides people into 16 types, depending on their self-reported preferences for things such as extroversion or introversion. The MBTI has been around since the 1960s, and an estimated two million people take it every year, a lot of whom seem to be management consultants; the test reportedly exerts considerable influence at McKinsey.

The Big Five: The Big Five personality traits was the model to comprehend the relationship between personality and academic behaviours. This model was defined by several independent sets of researchers who used factor analysis of verbal descriptors of human behaviour.

The five best-established traits, or Big Five, are: Openness, Conscientiousness, Extroversion, Agreeableness and Neuroticism.

The Enneagram: This is a model of nine personality types. Based on the work of Oscar Ichazo and Claudio Naranjo, it represents these personality types in a geometric figure. They include:

■  Reformers
■  Helpers
■  Achievers
■  Individualists
■  Investigators
■  Loyalists
■  Enthusiasts
■  Challenges
■  Peacemakers

The new entrant: A new study, based on huge sets of personality data representing 1.5 million people, has persuaded one of the staunchest critics of personality tests to conclude that maybe distinct personality types exist, after all.

In a report published in the journal Nature Human Behaviour, researchers at Northwestern University in Illinois identify four personality types: Reserved, Role models, Average and Self-centred.

“Personality types only existed in self-help literature and did not have a place in scientific journals,” one of the researchers announced. “This will change because of this study.”

— Agencies