◈Personality & psychology · 5 min
Type models sort people into a few well-defined categories. They are popular because they are simple and easy to remember. That same simplicity is also the source of their greatest limitations. Here are three well-known examples: the 16 types (MBTI-style), the Enneagram and DISC.
The 16 types (MBTI and its relatives)
The MBTI (Myers–Briggs Type Indicator) is the work of Isabel Briggs Myers and Katharine Briggs and builds on Carl Jung's 1921 book Psychological Types. It constructs the 16 types from four pairs: E/I (extraverted/introverted), S/N (sensing/intuitive), T/F (thinking/feeling), J/P (judging/perceiving), for example INFJ or ESTP.
Strengths: easy to understand, a good conversation starter about preferences (how I recharge, how I decide), and pleasant to take because of its positive wording.
Limits:
- Most traits are continuous, not two-poled: most people sit in the middle, so the "either/or" classification is often arbitrary. Someone in the middle of the E/I scale can land on the other side with the slightest shift.
- Reliability: on repeat testing a substantial share of people (in some studies roughly half) get a different type after a few weeks.
- Predictive power: weak at predicting job performance or successful relationships. The publisher itself advises against using it for hiring screens.
- Compared with the Big Five, the dimensions partly overlap (E/I resembles extraversion, J/P conscientiousness, S/N openness, T/F agreeableness), but neuroticism is left out entirely.
The Enneagram
The Enneagram describes nine "types", linked by a nine-pointed figure and by "wings" and "stress and growth arrows". The system comes from 20th-century, mainly spiritual and therapeutic traditions (Gurdjieff, Ichazo, Naranjo), not from laboratory research.
Strengths: it focuses on motivations (fears, desires) rather than just behaviour, which many people find deeper. Limits: the research evidence is mixed: some studies found moderate links with the Big Five, but the structure of nine types has not been clearly confirmed empirically, and the hypotheses about arrows and wings have been little studied.
DISC
DISC (Dominance, Influence, Steadiness, Conscientiousness) starts from William Marston's 1928 work on the "emotions of normal people" and is popular in the world of workplace communication. It describes four behavioural styles (for example decisive, inspiring, supportive, precise).
Strengths: a simple language that is easy to apply in teamwork. Limits: most DISC instruments are commercial and proprietary, independent peer-reviewed validation evidence is scarce, and four categories necessarily oversimplify.
What problem do they share?
- The Barnum effect: the type descriptions are broad and favourable, so almost everyone recognises themselves.
- Category error: continuous differences are "cut" into categories, so results are very uncertain near the boundaries.
- Self-fulfilling labels: if someone believes "I am an INFJ", they tend to describe themselves that way.
- Context dependence: behaviour also depends on the situation.
How to use them sensibly
- As a conversation starter: what do you like, what drains you, how do you like to work?
- Always ask: how much am I like this, and when am I not?
- Do not use them for selection, choosing a partner, diagnosis, or for pigeonholing others.
- If you want reliable, measurable self-knowledge, the Big Five (IPIP) is the best-researched basis, and type models can be treated as a supplementary language.