Personality Tests in Business: The Illusion That Reassures HR

Personality tests—MBTI, DISC, Big Five—are used by 20 to 80% of companies in recruitment. Their promise? To reveal who you really are, predict your behaviors, and find the ideal hire. The reality? Fragile tools that fail to predict what truly matters: real relational dynamics. So why do we still believe in them?

You know what fascinates me? It’s the absolute confidence we place in a 60-question survey to decide whether someone will bring the missing energy to a team or cause it to implode. As if ticking “somewhat agree” or “somewhat disagree” reveals the deep essence of your professional soul.
Spoiler: it doesn’t.

The Lie We Tell Ourselves Collectively

The global psychometric testing market is worth several billion dollars. The MBTI alone is reportedly used by 89 of the Fortune 100 companies. DISC appeals to SMEs and coaching firms. The Enneagram is making its way into management development seminars.
And it’s sold to us as science, as serious, as objective.

Except behind the pretty PDF report with its colorful charts, there’s a far less appealing reality: all these tests rely on self-reporting. You know what you think you are. Or worse, what you want people to think you are. In a hiring process, do you really believe people honestly tick “I struggle with authority” or “I tend to make everything about me”?

Test designers have multiplied tricks to work around this bias: rephrased questions, trap items, intimidating warnings. The problem? Up to 63% of candidates still admit to faking their responses. And research confirms it: there’s currently no foolproof method to detect these manipulations.

Welcome to the wonderful world of social desirability bias: that grain of sand that turns your “scientific” tool into corporate astrology.

My DISC Experience: Why Results Vary

Here’s a true story: a few years ago, I took a DISC test with a coach. Consistent result, I believed it. A year later, I retook the test for fun. Completely opposite result. I figured I’d missed something, so I tried again a week later: back to the first profile.

I wasn’t trying to cheat. I was sincere each time. And yet, my answers changed depending on my mood, my context, my perception of the moment. Because in reality, these tests don’t measure who you are. They measure who you think you are that day, at that hour.

The Gurus and Their Magic Categories

The worst part is that these tests aren’t even equivalent. We cheerfully mix:

The MBTI, born from Carl Jung’s brain and popularized by Isabel Briggs Myers without scientific training in psychology, which slots you into 16 boxes as if humanity were a game of Memory
The DISC, very corporate, four neat profiles to look good in seminars
The Enneagram, nine personality types presented as “deep structures,” which sounds mystical but rests on… nothing really solid

And these are just the best known. There are dozens of other tools—16PF, Sosie, PAPI, Process Com, etc.—each with its theoretical specificities. But they all share the same Achilles heel: they rely on self-reported responses and they put you in a box when you’re not necessarily the same person whether you’re stressed, confident, facing your boss or your friends.

Against them, the Big Five (OCEAN) appears as the serious student. It’s the only model based on decades of empirical research. But beware: more robust doesn’t mean infallible. It measures tendencies, not certainties. It says nothing about your motivations, your context, or how you’ll actually behave in a team.

In short, even the class valedictorian remains an imperfect tool we oversell.

The Barnum Effect, or Why “That’s So Me!”

You know why these tests seem relevant? Because they use descriptions vague enough for everyone to see themselves in them. It’s the Barnum effect: “You appreciate autonomy while valuing teamwork.” Or: “You have great potential, even if you sometimes doubt yourself,” etc. Obviously, who doesn’t recognize themselves in that?

We fall for it because we want to believe. Because having a report that explains “who we are” is reassuring. It gives the impression of self-understanding. But it’s just a distorted mirror flattered by our need for coherence.

The Hidden Promise: Creating the Perfect Team

The Official Narrative vs. Reality

If HR loves these tests, it’s because they promise to find the ideal hire: the one who’ll energize the sleepers, temper the egos, stand up to the dominants without blowing everything up. Or conversely, avoid the “rigid one” who’ll make an already bureaucratic culture even more so. Behind the scenes, the talk is unfiltered: “definitely not a troublemaker,” “someone who can hold their own against Mr. Loudmouth,” “we need someone adaptable,” and the classic “we’ve already had our fill of unmanageable profiles.”

The problem? These expectations rest on nuances that tests are incapable of detecting.

The Impossible Prediction of Relational Dynamics

Tests give us some indications about a profile, but none can distinguish between:

The creative outsider, whose ideas challenge without delegitimizing, who brings a fresh perspective while respecting the rules of the game
The toxic outsider, who systematically questions decisions, ignores instructions, seeks permanent confrontation

Or between:

The strong personality who’ll enrich debates
The one who’ll poison them

Or between:

The calm profile who’ll stabilize the team
The one who’ll just slow everything down

These nuances between constructive and toxic traits aren’t measurable by a questionnaire. They’re relational patterns that reveal themselves over time, in real interaction with a given company culture, with specific personalities.

When Tests Become Alibis

And that’s where the discourse really becomes perverted. Because when conflicts arise within teams, it becomes so easy to pull out the tests, and we’re told it’s not because of problematic behaviors, but because we’re “different“—and we need to “understand” and “respect” these differences. Except in practice, this forced attempt at reconciliation, where tolerance is brandished left and right like a talisman, ends up transforming into a convenient alibi for managerial cowardice.

We’ve all witnessed situations where one person monopolizes conversation, neutralizes collective decisions, instills a toxic climate, and where, under the guise of a supposed “psychological typology,” the rest of the team is told to “understand their profile,” to “show empathy,” and, in reality, to adapt to the unacceptable while management shirks all responsibility.

When it’s time to make tough calls, set boundaries, address behavior, or own an unpopular decision, many prefer to delegate courage to a supposedly neutral system rather than exercise it themselves.

So Why Do We Keep Using These Tests?

Because they promise a simple answer to a complex problem, a reassuring framework in the face of human uncertainty, and especially a convenient way to avoid fully owning decisions that remain, regardless of what we say, profoundly human. They give the illusion of objectivity. A report, a chart, an official document. In a world where every HR decision can be challenged, that little PDF serves as a shield: “It wasn’t me who decided, it was the test.”

Except legally, it protects nothing. An unvalidated test, poorly used or abusively interpreted can actually weaken a decision and backfire on the organization. We’re just shifting responsibility. We pretend to be rational when we’re just afraid to decide.

What We Should Do Instead of These Tests

For managers: be careful not to confuse “ideal profile” with “clone of yourself.” Tests often steer you toward what reassures you rather than what your team needs.
For candidates: these tests are a small window into what your recruiters really think—and if you want an even juicier glimpse, check out my article on sneaky interview tests and what they reveal about recruiters.

The truth? The best way to evaluate a human remains through another human: with structured interviews, real situational exercises, concrete behavioral observations over time.

Yes, our humanity makes us fallible, irrational, unpredictable. We’re difficult to assess because we’re not objects. And that frustrates minds dreaming of magic algorithms.

But it’s precisely from our wanderings that the greatness of a project is born, the warmth of a team, and the success of an adventure.
No test will ever replace a real look, a real conversation, a real encounter!