The problem with personality testing in hiring
Personality assessments are now standard in corporate hiring, yet most HR teams cannot answer a simple question: what does the science behind the tool they use actually say?
The personality testing market is large, fragmented, and filled with tools that range from rigorously validated instruments to repackaged typologies with no predictive basis. Choosing the wrong tool does not just waste money — it can introduce bias, create legal exposure, and result in hiring decisions that are no better than chance.
Two tools dominate the conversation in corporate environments: HEXACO and DISC. They are often mentioned in the same breath, but they come from fundamentally different traditions, serve different purposes, and have dramatically different evidentiary bases. Understanding that distinction is the first step toward making personality assessment actually useful.
HEXACO: a model born from peer-reviewed research
HEXACO is a six-factor model of personality developed by psychologists Michael Ashton and Kibeom Lee, with roots in a research program that began in the late 1990s. The model emerged from a methodological approach called the lexical hypothesis: the idea that all meaningful personality differences between humans are, over time, encoded in natural language. Researchers analyze thousands of personality-descriptive adjectives across multiple languages, apply factor analysis, and let the structure of human personality emerge from the data.
The six factors are:
- H — Honesty-Humility: sincerity, fairness, greed-avoidance, modesty
- E — Emotionality: fearfulness, anxiety, dependence, sentimentality
- X — eXtraversion: social self-esteem, social boldness, sociability, liveliness
- A — Agreeableness: forgiveness, gentleness, flexibility, patience
- C — Conscientiousness: organization, diligence, perfectionism, prudence
- O — Openness to Experience: aesthetic appreciation, inquisitiveness, creativity, unconventionality
The HEXACO model has been validated across dozens of languages and cultures, published in leading peer-reviewed journals including the Journal of Personality and Social Psychology and Psychological Assessment, and replicated by independent research groups that have no commercial relationship with the model's authors.
DISC: a commercial framework with thin academic backing
DISC traces its origins to a 1928 book by psychologist William Moulton Marston, Emotions of Normal People, which proposed four primary emotional responses: Dominance, Inducement, Submission, and Compliance. Marston himself never intended this as an assessment tool — he was building a theoretical framework. The commercial DISC products sold today were developed decades later by other parties.
The four DISC styles describe behavioral tendencies in workplace contexts:
- D — Dominance: direct, results-oriented, assertive
- I — Influence: enthusiastic, optimistic, collaborative
- S — Steadiness: patient, reliable, supportive
- C — Conscientiousness: analytical, precise, systematic
DISC is widely used — estimates suggest over a million assessments are completed annually — but widespread use is not evidence of validity. Independent academic research on DISC's psychometric properties is sparse, and most studies that do exist are conducted or funded by organizations that sell DISC products. The four-style structure does not emerge from factor-analytic research on personality. It was imposed as a theoretical framework, not discovered from data.
The scholarly gap — what the meta-analyses actually say
The evidence base for personality assessment in hiring is substantial, but it is built almost entirely on the Big Five model and, more recently, HEXACO. The landmark meta-analysis by Barrick and Mount (1991) established that Conscientiousness predicts job performance across virtually all occupations. Subsequent work by Schmidt and Hunter (1998) demonstrated that combining cognitive ability with personality assessment produces the highest predictive validity of any selection method short of work sample tests.
HEXACO fits cleanly into this research tradition. DISC does not. There is no large-scale meta-analytic evidence that DISC scores predict job performance, tenure, leadership effectiveness, or any other organizationally relevant outcome with the kind of validity coefficients that justify using it as a hiring tool.
This matters because using an unvalidated tool as part of a hiring decision can constitute disparate impact discrimination if the tool produces adverse outcomes for protected groups — and courts do not accept commercial popularity as a substitute for demonstrated validity.
The decisive difference: Honesty-Humility
The most practically significant difference between HEXACO and any other major personality model is the Honesty-Humility factor — a dimension that is entirely absent from the Big Five and has no equivalent in DISC.
Honesty-Humility measures the degree to which a person is sincere rather than deceptive, fair rather than exploitative, modest rather than self-aggrandizing, and resistant rather than susceptible to material temptation. Empirical research has established it as the single strongest personality predictor of counterproductive workplace behaviors: theft, fraud, deliberate sabotage, manipulation of colleagues, and gaming performance metrics.
For roles that involve financial authority, client trust, access to sensitive data, or management of other people, Honesty-Humility is arguably more predictive of organizational risk than any other single personality variable. No DISC profile captures this. An employee who scores as a high-D (Dominant) in DISC may score high or low on Honesty-Humility — the DISC framework cannot tell you which.
When DISC still has a place
DISC is not without value — it is simply misapplied when used for hiring decisions. Its actual strengths lie in what happens after a hire is made.
DISC is effective as a team communication tool. Because the four styles describe preferred ways of working and interacting rather than deep trait structures, DISC profiles can help newly formed teams understand each other's working styles, anticipate communication friction, and calibrate how to assign tasks. A team workshop built around DISC profiles can be genuinely productive. A hiring decision influenced by DISC profiles is not.
The appropriate sequencing is: use HEXACO (and cognitive assessment) in selection, use DISC in team integration and development. These are complementary if you understand what each tool is and is not designed to measure.
Practical implications for hiring teams
If your organization is currently using DISC as part of a structured hiring process, the most important step is to stop using DISC scores as a filtering or scoring mechanism. You can retain DISC for post-hire team development without any disruption to that use case.
When evaluating a HEXACO-based tool, look for implementations that score candidates at the factor level (not just type categories), include the full Honesty-Humility facets, and provide a role-fit interpretation rather than a raw score dump. Shorter versions (HEXACO-60) are sufficient for most hiring contexts. The 100-item version adds facet-level detail that is useful when the role requires very specific trait combinations.
The broader question of which assessment to use is becoming easier to answer with the emergence of AI-assisted platforms. Tools like Calibers.ai can administer a validated HEXACO questionnaire, score it with full psychometric rigor, and generate a structured personality report in the same workflow as technical and cognitive assessments — removing the operational friction that once made validated personality testing feel cumbersome compared to simpler commercial alternatives.
The science on which model to use is not contested. What has historically been contested is how practical it is to use the better model. That gap is closing.