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Personality Assessments: Separating Science From Nonsense

Why you should forget about the MBTI and focus on real science.

Key points

  • While the assessment of personality is becoming increasingly important in job recruiting, many denounce its limitations and dangers.
  • Such denunciations are based on the use of poor and unreliable tools, which have nothing to do with science.
  • When they are well-constructed and science-based, personality assessments bring great added value to HR or business decision-makers.

While the assessment of personality is becoming increasingly important in hiring processes and HR decisions, many denounce its limitations and dangers. It is common to hear that personality inventories merely contribute to putting people into boxes, rather than helping business leaders to better understand the complexity of human behavior.

The more skeptical are going as far as to think that these personality assessments are some sort of an aberration in a world that demands more authenticity and humanity in decisions. If these debates raise good questions, they, unfortunately, bring threatening answers. Indeed, the criticisms that emerge are fueled by shortcuts and misunderstandings, or by tools where popularity trumps accuracy.

If one does warn against the naive use of inaccurate assessments, we should not form our opinion nor consider all assessments the same way, however, solely on the basis of this warning.

From nonsense…

Among comforting pseudoscience, the MBTI (Myers-Briggs Type Indicator) is king. While it is used by more than 2 million professionals each year, research shows that, if the tool can seduce by its intuitiveness, its psychometric qualities do not support its usefulness in organizational decisions: it creates an illusion of knowing about the personality of someone but would serve no other purpose than to animate water-cooler talks. For example:

  • Studies question the validity of MBTI

  • Across a 5-week test-retest interval, research shows that 50 percent of people will receive a different classification on one or more of the scales

  • There is no evidence showing that MBTI measures truly dichotomous preferences, and statistical analysis does not support the theory behind MBTI

  • The last study mentioned also shows that MBTI does not offer a complete picture of one’s personality, with "Neuroticism" being poorly captured

  • MBTI profiles don’t seem to predict team development or processes

The nonsense of MBTI is similar to lots of typological personality tests which are based on the theory of psychological types. Initiated by the Jungian typology—from the name of its author, the Swiss psychiatrist Carl Gustav Jung—this theory postulates that types oppose individual differences in a qualitative way: for example, the extrovert (E) and introvert (I) types.

Unfortunately, warnings from the author himself about potential misunderstanding, or abusive overgeneralization of his work, have not stopped the commercial appetite of some. The mistake made by these tools lies in the fact that they consider personality as a qualitative variable, rather than a quantitative one: in this sense, as personality assessments’ detractors can rightly assert, typological tests tend to put people into boxes. However, research shows that personality should be considered in a quantitative and continuous way. Individuals can be at any point on personality the continuum, and their position determines how they will act.

To understand this logic better, think about height‚ a quantitative variable, which is defined on a continuum in centimeters. Now imagine if height were measured according to a two-dimensional qualitative model: either people are tall, or they are short. Beyond the absurdity this measurement would bring, it turns out to be relatively poor and reductive. An individual:

  • Could become tall or short by gaining or losing just one centimeter

  • Could not be considered taller or shorter than another individual at either extreme of the two categories

Worse, as already mentioned, half of people would be classified in the opposite category when measuring themselves again 5 weeks later.

…to Science

When addressing personality assessments, it’s essential to clarify what we’re really talking about: typological tests—such as the MBTI—or tests based on a quantitative design, where personality is considered through traits. The latter are scientifically and empirically supported, and are, for example, based on the Big Five or Five-Factor Model, which has demonstrated solid validity. While these models have long been reserved for an informed public of experts, they're—fortunately—becoming easier and more accessible for businesses. According to the FFM model, personality is organized into five independent domains: Extraversion, Agreeableness, Openness, Conscientiousness, and Neuroticism.

A great deal of research shows that these domains reliably predict job-related outcomes:

The links between the FFM model and performance are clearer when considered in a given context. For example, using the trait activation theory, studies show that:

  • Conscientiousness and Openness have stronger correlations with job performance in roles providing autonomy and independence (e.g., anthropologist).

  • Emotional stability, Agreeableness, and Extraversion are more predictive of job performance in roles that require strong social skills (e.g., psychologist).

  • Agreeableness is negatively associated, and Extraversion positively associated, with job performance in competitive environments (e.g., sales manager).

  • Openness is more important to job performance in tasks with a strong need for innovation (e.g., scientific roles, advertising).

  • Extraversion, Agreeableness, and Emotional stability are more related to performance in occupations that involve working with disgruntled people (e.g., flight attendant).

When they are well-constructed, personality assessments bring great added value to HR or other business decision-makers. By reducing the biases of our human cognition and overcoming the limits of intuition, personality assessments allow for making more informed and fairer decisions in hiring, management, and talent development.

Ultimately, the question is not about whether it is relevant to assess personality, but rather how to do it. Before forming an opinion on the use of personality assessments, people should have the humility to challenge their own preconceptions and question the opinions of many uninformed experts, who may make hasty or negative judgments by wrongly categorizing all the assessments following a bad experience, or continue to use and promote poorly constructed tests that are useless.

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