TL;DR: Personality assessments won’t hire for you, but they can tilt the odds in your favor—especially for reliability and conduct risk—when you pick the right traits, link them to the job, and pair them with structured interviews and work samples. Don’t use typology tools (like MBTI®/DiSC) or clinical inventories for hiring decisions.
A quick guide to the Big Five
Psychologists have studied personality for more than a century, but one model consistently holds up across cultures and decades of research: the Big Five (OCEAN: Openness (to experience), Conscientiousness, Extraversion, Agreeableness, Agreeableness, and Neuroticism). It describes personality through five broad, measurable traits that each exist on a continuum:
You’ll also hear about HEXACO, a six‑factor model: Honesty–Humility, Emotionality, eXtraversion, Agreeableness, Conscientiousness, and Openness. It’s very similar to the Big Five, but with two useful differences:
- It adds Honesty-Humility—a dimension that captures sincerity, fairness, modesty, and resistance to entitlement or status-seeking at others' expense. This one matters because it's strongly linked to ethics and counterproductive work behavior (CWB)—things like cutting corners, misusing resources, or mistreating colleagues. If you run a business where trust and compliance are non-negotiable (which is most businesses), Honesty-Humility is directly relevant.
- It re-balances Emotionality and Agreeableness slightly, which helps separate "being anxious" from "being cooperative." That nuance can sharpen the signal for roles that require steady judgment and diplomacy.
None of these traits are “good” or “bad” in the abstract. They’re tendencies, and whether they help or hurt can depend on the job, the person, and your leadership.
What personality assessments can (and can’t) predict
When used well, personality measures can predict a meaningful slice of job performance. Conscientiousness, in particular, shows up again and again as a small‑to‑moderate predictor across many kinds of work. Extraversion tends to help in sales, client‑facing, and leadership roles where influencing matters. Openness often relates to learning and adaptability, which is handy when the role changes quickly.
They can also reduce risk. Lower Conscientiousness and lower Agreeableness are associated with more CWB. In HEXACO, low Honesty–Humility is a red flag for unethical behavior. If your concern is reliability, safety, or culture, these signals are useful.
What personality can’t do is make the decision for you. Think of these scores as probabilities, not prophecies—like a forecast calling for a 70% chance of rain: you carry an umbrella, but you know it still might not pour. They nudge the odds toward a better hire; they don’t guarantee an outcome.
What they can help predict
- Job performance (across jobs):
- Conscientiousness shows up again and again as a small‑to‑moderate predictor of performance and training success across roles.
- Extraversion tends to help in sales/leadership and client‑facing work.
- Openness often relates to learning and adaptability.
- Counterproductive work behavior (CWB):
- In lower Conscientiousness/Agreeableness
- Low Honesty–Humility relate to higher misconduct risk (e.g., theft, policy violations).
- Incremental validity: Personality adds prediction on top of structured interviews, work samples, and general mental ability (GMA)—especially when you include integrity measures.
What they can't do
- Replace job-relevant methods like work samples/SJTs or structured interviews.
- Deliver deterministic yes/no answers—scores are probabilistic signals, not verdicts.
- Diagnose clinical conditions.
Why prediction varies
Some jobs leave almost no room for personal style; psychologists call those “strong situations.” They’re tightly scripted, checklist‑driven, and compliance‑heavy—there’s basically one right way to act (think a call‑center agent reading a script or a technician following a step‑by‑step procedure). By contrast, “weaker situations”—enterprise sales, product strategy, leading change—have looser playbooks and ask for judgment. According to Trait Activation Theory, the more a job provides cues and discretion, the more a person’s traits show up in behavior: heavy social interaction tends to activate Extraversion, while autonomy and high standards make Conscientiousness matter more. That’s why personality adds less predictive value in strong situations and more where people have latitude.
Fairness, faking, and format
On average, personality tests show smaller group score differences than cognitive ability tests. That’s helpful when you care about both prediction and fairness. You still need to monitor outcomes by protected group, but you’re starting from a better place.
Yes, candidates can try to look good on self‑report inventories, and several studies have shown candidates are willing to lie on tests to give the answers they think employers want to hear. Design choices make that manageable. Modern forced‑choice formats, scored with item response theory, make it harder to inflate scores and still produce norm‑referenced results you can compare across people. Clear instructions and balanced item wording help too.
Another design choice is bandwidth. Broad traits are fine for a general picture. If you want sharper prediction, use facet‑level scales aligned to the job, such as “dependability” and “achievement” under Conscientiousness for reliability‑critical roles.
What not to use
Skip type indicators like MBTI® or DiSC for hiring. They’re excellent for self‑awareness and team conversations, but they weren’t designed to predict job performance, and their publishers say not to use them for selection.
Avoid clinical/diagnostic inventories (for example, MMPI) in pre‑offer screening. In the United States, those can be treated as medical exams under the Americans with Disabilities Act, which makes them off‑limits before a job offer and risky even after, unless there’s a strong, documented job‑related reason.
Finally, if a vendor can’t show job relevance, validity evidence, subgroup analyses, and clear documentation, don’t use the tool for hiring. Full stop.
A simple plan to use personality
- Start with the job. Write down the outcomes that matter and the real situations the role encounters. If the work demands follow-through, map that to Conscientiousness; if it demands ethical judgment and access to resources, map that to Honesty-Humility.
- Pick instruments built for selection. Look for Big Five or HEXACO tools with criterion validity in comparable roles, facet reporting, norm-referenced scores, and a faking-resistant format.
- Combine methods on purpose. Put personality alongside structured interviews, work samples or situational judgment tests, and where appropriate, general mental ability or job-knowledge tests. Each method adds a different slice of prediction; together they're stronger than any single tool.
- Validate locally and monitor fairness. Even if a publisher provides strong evidence, collect your own. Track outcomes by group, revisit weights, or cutoffs if adverse impact appears, and document what you did.
- Respect the candidate experience. Be clear about purpose, keep assessments reasonable in length, ensure accessibility, and protect privacy. You'll attract better talent and get better data.
Personality is a decision aid, not a verdict. Use it to ask better follow-up questions and to design better interviews, not to rubber-stamp a yes/no.
How Hesion Leadership Consulting can help
We respect the science on personality. There’s real signal there, but our default recommendation is not to use personality assessments in the hiring decision itself. Keeping personality out of pre‑hire keeps your process clean and defensible. It eliminates gray areas (Did a candidate “game” a self‑report? Is this trait truly job‑critical?), reduces privacy concerns, and lets you point to evidence that looks like the job.
Instead, we start with the work. We map the role, then build a selection process around structured interviews, work samples, and situational judgment tests—the kinds of tools that show how someone thinks and performs in your actual context. When it adds value, we include job‑knowledge or general mental ability measures, and we wrap it all in clear rubrics, interviewer training, and validation and fairness monitoring.
Personality fits in after hire. Use it as a conversation starter to build trust and clarity. Share a plain‑English summary of each person’s results and talk about how you each work best—how decisions get made, how updates are shared, and how to raise concerns early. Turn a handful of insights into simple “how we’ll work together” agreements and refer back to them in 1:1s and team meetings. When a new leader arrives, host a team conversation to swap preferences, co‑write a short set of ground rules, and pair people whose strengths complement each other on key projects. Keep it safe: discuss themes rather than raw scores, focus on behaviors instead of labels, and never link results to pay or performance reviews.
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