Big Five vs HEXACO, why some researchers count six traits

The HEXACO model describes personality with six traits instead of five. Five closely resemble the Big Five; the sixth, Honesty-Humility, captures the tendency to be sincere, fair and modest rather than manipulative or vain. If you have taken a Big Five test, most of what HEXACO measures is already in your result, divided up a little differently.

Where the sixth trait comes from

Both models come from the same method: collect the adjectives a language uses to describe people and see which ones go together. Michael Ashton, Kibeom Lee and colleagues reran these analyses in seven languages, Italian included, and found a six-factor structure in all of them (Ashton and colleagues, 2004). Hence the name: Honesty-Humility, Emotionality, eXtraversion, Agreeableness, Conscientiousness, Openness (Ashton and Lee, 2007).

The picture is messier than it is usually told. One of the first Italian lexical studies found five factors close to the Big Five, but with Agreeableness and emotional stability blended together (Caprara and Perugini, 1994); other work on Italian trait words recovered only the first three factors with confidence (Di Blas, Forzi and Peabody, 2000). Neither five nor six factors emerge cleanly from every language.

What changes compared with the Big Five

Besides the new trait, HEXACO moves two boundaries. Irritability and anger, which sit in Neuroticism in the Big Five, move to the low pole of HEXACO Agreeableness: being disagreeable there mainly means getting angry and holding grudges. Sentimentality, partly part of Big Five Agreeableness, moves to Emotionality, alongside anxiety and vulnerability (Ashton and colleagues, 2004). Extraversion, Conscientiousness and Openness stay much the same.

Does Honesty-Humility predict more?

For misconduct, yes. In three samples of employees in Australia, Canada and the Netherlands, Honesty-Humility was the trait most strongly tied to workplace delinquency, with correlations between -.34 and -.55, and the six-trait model predicted it better than the five-trait one (Lee, Ashton and de Vries, 2005). A later meta-analysis estimates that HEXACO explains about 32% of the differences in workplace deviance, against 19% for the Big Five (Pletzer and colleagues, 2019). A review of hundreds of meta-analyses ties Honesty-Humility above all to the tendency to exploit others (Zettler and colleagues, 2020).

How much is missing from your Big Five result

Less than it seems. Honesty-Humility overlaps substantially with Big Five Agreeableness, especially the facets about sincerity and modesty (Ashton and Lee, 2005). How much is captured depends on the questionnaire: in the 2005 study its correlation with Agreeableness ranged from .12 to .52 depending on the Big Five instrument used (Lee, Ashton and de Vries, 2005).

So which model is right

Neither is "the true one". They are two ways of cutting the same territory, and for a general profile they say very similar things. HEXACO has a clear edge when honesty and fairness are the question; the Big Five have more decades of research behind them, more published norms and public-domain questionnaires such as the IPIP-NEO, which is what we use. The official HEXACO inventory, by contrast, is free only for academic research and may not be used on sites open to the public (hexaco.org).

In our test, the two facets closest to the sixth trait are called Morality and Modesty, and they belong to Agreeableness: you will find them in the full report with the other 28. The test below takes about 10 minutes.