Personality Assessment Systems: Mental Models for Human Variation

In my exploring mental models, I’ve become fascinated by the frameworks we use to understand each other. Personality assessment systems are essentially mental models for human variation - tools that help us pattern-match behaviors, preferences, and tendencies. While I’m naturally skeptical of oversimplified classifications (which you’ll see reflected below), these systems persist because they serve a deep human need to make sense of our differences.

This is my growing collection of notes on major personality frameworks, both mainstream and alternative, viewed through the lens of what they reveal about our desire to categorize and understand the mind.

Major Personality Assessment Systems

Myers-Briggs Type Indicator (MBTI)

Based on Carl Jung’s cognitive functions theory, categorizing people into 16 personality types through four dichotomies (Extroversion/Introversion, Sensing/Intuition, Thinking/Feeling, Judging/Perceiving).

“In so far as such a type is an outspoken attitude, it is characterized by the properties of the function plus the properties of extroversion.” - Carl Jung

• Current perspective: A corporate folk taxonomy with significant cultural influence despite poor empirical validity, properly debunked by Goodbye to MBTI, the Fad That Won’t Die | Psychology Today; demonstrates how categorical thinking about personality fulfills a social need.

What fascinates me about MBTI is not its accuracy (which is questionable), but how it reflects our desire to create coherent narratives about ourselves. This connects to my thoughts on “Work as a Game” - how we adopt certain identities and play within those constraints. Some people approach work through the lens of their perceived type, creating boundaries and permissions for themselves that shape their experience.

Big Five (OCEAN)

Empirically derived personality dimensions (Openness, Conscientiousness, Extroversion, Agreeableness, Neuroticism) measured on continuous scales rather than discrete categories.

“Personality traits are not types of people but dimensions of individual differences.” - Robert McCrae

• Current perspective: The latest “standard model” of personality psychology, with cross-cultural validity but tension between its statistical strength and limited intuitive accessibility for everyday use; illustrates the gap between scientific and social psychology

HEXACO

Expands on Big Five by adding Honesty-Humility as a sixth dimension, suggesting personality has more facets than previously recognized.

“The discovery of the H factor represents a breakthrough in our understanding of personality.” - Kibeom Lee

• Current perspective: A refinement representing ongoing evolution in trait psychology; highlights how moral dimensions of personality remain underexplored in traditional models despite their social significance.

Enneagram (RHETI or IVQ)

A spiritual-psychological system identifying nine interconnected personality types, each driven by core fears and desires, with wings and stress/growth directions.

“The Enneagram doesn’t put you in a box. It shows you the box you’re already in and how to get out of it.” - Don Richard Riso

• Current perspective: Occupies a unique middle ground between spiritual tradition and contemporary psychology; its focus on motivational patterns and personal growth gives it enduring appeal despite limited empirical validation.

My Thought - What makes it stick

In my own explorations of PKM systems and knowledge organization, I’ve found interesting parallels with how we organize information about ourselves. The frameworks that tend to stick with us aren’t always the most scientifically valid, but rather those that provide us with meaningful patterns and actionable insights. My fascination with these systems isn’t about finding the “correct” one, but understanding how they facilitate different kinds of self-awareness and interpersonal understanding.

Additional Notable Systems

Cattell’s 16PF

Identifies 16 primary personality factors through factor analysis of observable behavioral variables.

“Personality is that which permits a prediction of what a person will do in a given situation.” - Raymond Cattell

• Current perspective: A historically significant precursor to modern trait psychology; illustrates the challenge of balancing comprehensiveness and parsimony in personality models.

Eysenck’s PEN Model

Focuses on three fundamental dimensions: Psychoticism, Extroversion, and Neuroticism.

“Personality is more or less stable and enduring organization of a person’s character, temperament, intellect, and physique.” - Hans Eysenck

• Current perspective: Notable for attempting to link personality dimensions to biological substrates; pioneered the biological approach to personality now supported by behavioral genetics research.

DiSC Assessment

Examines behavioral styles through four main dimensions: Dominance, Influence, Steadiness, and Conscientiousness.

“People are different, but they’re predictably different.” - William Marston

• Current perspective: Exemplifies pragmatic organizational tools designed primarily for workplace application rather than theoretical advancement; prioritizes simplicity and applicability over comprehensive accuracy.

Socionics

A Russian adaptation of Jung’s theory, expanding MBTI concepts with information metabolism theory.

“Each type of personality represents a different kind of psychological information processor.” - Aushra Augusta

• Current perspective: Demonstrates how psychological theories evolve differently across cultural contexts; developed extensive theoretical elaboration in Eastern Europe largely isolated from Western empirical psychology.

Holland Codes (RIASEC)

Career-focused personality model categorizing people into six types: Realistic, Investigative, Artistic, Social, Enterprising, and Conventional.

“People search for environments that will let them exercise their skills and abilities, express their attitudes and values.” - John Holland

• Current perspective: Successfully bridges personality theory and practical application in vocational counseling; illustrates how domain-specific models can outperform general personality frameworks for targeted purposes.

Five Factor Model (FFM)

A more detailed version of Big Five that breaks down each factor into six facets.

“Personality traits are not simply descriptions of static characteristics, but dynamic qualities that predict behavior.” - Paul Costa

• Current perspective: Represents the tension in personality assessment between broad dimensions and nuanced specificity; shows how hierarchical models attempt to capture both overarching patterns and meaningful variations.

The proliferation of these systems reminds me of different note-taking methodologies I’ve explored in my PKM journey. Some are elegantly simple but lack depth, while others offer comprehensive frameworks that can feel overwhelming in practice. What matters most isn’t finding the “perfect” system, but rather which one helps you recognize meaningful patterns that might otherwise go unnoticed.

Beyond Psychology: Alternative Typologies

While the systems above have varying degrees of scientific backing, I find value in studying whatever pseudoscientific frameworks are out there. They reveal cultural patterns, historical contexts, and human needs that more rigorous systems sometimes overlook. Approaching these with curiosity rather than credulity offers insights into how we’ve tried to make sense of human differences across time and cultures. Everything is a dialectic in the end – another angle to learn a little more.

Western Astrology

Connects personality traits to zodiac signs based on celestial positions at birth, with 12 main archetypes influenced by elements, modalities, and planetary aspects.

“As above, so below; as within, so without.” - Hermes Trismegistus (The Emerald Tablet)

• Current perspective: Despite lack of empirical support, persists as a culturally ubiquitous personality language; demonstrates how symbolic systems satisfy human needs for meaning, identity, and cosmic connection beyond scientific validity.

Chinese Zodiac

A 12-year cycle associating birth years with animal archetypes, each carrying distinct personality traits, compatibilities, and life patterns.

“One’s destiny is determined by the year of their birth, as each animal brings its own nature to the soul.” - Traditional Chinese Proverb

• Current perspective: Functions as both cultural heritage and social shorthand across East Asia; exemplifies how personality typologies deeply embed in cultural practices while shaping interpersonal expectations.

Four Temperaments (Humoral Theory)

Ancient Greek system categorizing personalities into Sanguine, Choleric, Melancholic, and Phlegmatic based on bodily fluids.

“The body’s humors guide not just health, but the very nature of one’s character.” - Hippocrates

• Current perspective: Historically significant as Western medicine’s first attempt to link physiology and psychology; illustrates how obsolete scientific frameworks can nonetheless contain enduring insights about personality patterns.

Ayurvedic Doshas

Indian system identifying three main energy types (Vata, Pitta, Kapha) that influence both physical constitution and personality.

“As is the microcosm, so is the macrocosm; as is the atom, so is the universe.” - Upanishads

• Current perspective: Represents holistic integration of physical, mental, and spiritual aspects of personality largely absent in Western models; showcases how indigenous knowledge systems approach mind-body connections.

Blood Type Personality Theory

Popular in East Asia, particularly Japan, linking ABO blood types to personality traits and compatibility.

“Blood type is to personality what the stars are to destiny.” - Masahiko Nomi

• Current perspective: Demonstrates how pseudoscientific frameworks can gain widespread cultural acceptance when they align with existing social needs and practices; functions as social currency despite lack of biological basis.

Element Personality Types

Various traditions associating personality with natural elements (Fire, Earth, Air, Water), found in multiple cultures.

“Every soul bears the imprint of one element above all others.” - Paracelsus

• Current perspective: Exemplifies how metaphorical thinking about personality transcends cultural boundaries; elemental correspondences provide intuitive frameworks that persist despite (or because of) their symbolic rather than literal nature.

Hand Analysis

Beyond fortune-telling, a system analyzing personality through hand shape, finger length, and line patterns.

“The hand is the visible part of the brain.” - Immanuel Kant

• Current perspective: Straddles boundary between pseudoscience and emerging biological research on developmental markers; digit ratio studies suggest some physical features may indeed correlate with personality traits, albeit in limited ways.

Color Personality Theory

Associates personality traits with color preferences and responses.

“Colors, like features, follow the changes of the emotions.” - Pablo Picasso

• Current perspective: Represents the perennial appeal of sensory-based personality categorization; leverages universal color symbolism while typically overextending limited correlational evidence.

Birth Order Theory

Popularized by Alfred Adler, suggesting personality is significantly influenced by one’s position among siblings.

“The position in the family leaves an indelible stamp upon the style of life.” - Alfred Adler

• Current perspective: Illustrates the challenging lifecycle of psychological theories—initially compelling and intuitive, embraced culturally, but gradually constrained by empirical evidence showing effects are smaller and more contextual than originally claimed.

My Current Thinking

My only conclusion comes from the great William James’ work “The Principles of Psychology” (1890).

“We may practically say that a man has as many social selves as there are individuals who recognize him and carry an image of him in their mind.”

I’m open to many theories these days because I believe we have many selves.

As a model, personality frameworks are valuable windows into the urge for understanding. The best ones aren’t necessarily those with the strongest scientific validation, but those that provoke useful insights in specific contexts. I’m drawn to systems that acknowledge their limitations while still offering conceptual tools for navigating human differences.

What interests me most is how these systems reveal our persistent desire to create order from the messy complexity of human variation—the frameworks we choose reflect not just what we value, but how we wish to see ourselves and others.

This collection remains a work in progress, part of my broader digital garden of evolving thoughts on mental models, knowledge systems, and patterns of human understanding. It’s neither done nor believed to be the only way to explain any of it.