The Science of Personality
From skull bumps to big data: A complete overview of the history, validity, and current state of personality profile tests.
Introduction: Astrology for Business?
The personality testing industry is worth over $2 billion. Companies use them for hiring, team building, and leadership development. But not all tests are created equal. While some provide deep, scientifically valid insights into human behavior, others are little more than "corporate horoscopes." This infographic separates the rigorous science from the pseudoscience, exploring how we moved from measuring skull bumps to the statistical robustness of the Big Five.
1. The Evolution of Assessment
The quest to categorize human character is centuries old. We have moved from physical measurements to psychoanalysis, and finally to lexical statistical analysis.
Phrenology & The Humors
Concept: Personality is determined by the shape of the skull (Phrenology) or bodily fluids (Humors).
Status: DEBUNKED. Completely abandoned. No physiological basis exists linking skull bumps to traits like "benevolence" or "destructiveness."
Projective Tests & Typology
Concept: Rorschach (Inkblots) and Jungian Types (basis of MBTI). Interpreting ambiguous stimuli or sorting people into binary "types" (Introvert OR Extrovert).
Status: MIXED/DECLINING. Rorschach has poor reliability. Typology is popular in business but criticized by scientists for lacking nuance.
The Trait Era (Big 5)
Concept: The Lexical Hypothesis. Researchers found that personality descriptors in language cluster statistically into 5 main factors. It measures traits on a spectrum (0-100), not binary types.
Status: INDUSTRY STANDARD. The gold standard for academic research and high-stakes assessment.
2. Popularity vs. Scientific Validity
Just because a test is popular doesn't mean it's accurate. This chart compares common frameworks based on their market ubiquity versus their acceptance in peer-reviewed psychology.
MBTI (Myers-Briggs)
Extremely popular in corporate training but has low test-retest reliability (50% get different results after 5 weeks). Considered "low validity" for hiring.
The Big Five (Five Factor)
High validity and reliability. It predicts job performance, relationship success, and health outcomes. Less "viral" marketing, but scientifically superior.
3. The Current Standard: The Big Five
Also known as the OCEAN model. Unlike types, which put you in a box, traits place you on a bell curve. Most people are somewhere in the middle.
Sample "Leader" Profile
Data represents a hypothetical profile often associated with successful management roles.
Openness to Experience
Imagination, curiosity, and willingness to try new things. High scorers are creative; low scorers are pragmatic.
Conscientiousness
Self-discipline, duty, and achievement-striving. The single best predictor of job performance across all occupations.
Extraversion
Energy, positive emotions, and assertiveness. High scorers seek stimulation; low scorers (introverts) need less external stimulation.
Agreeableness
Compassionate and cooperative rather than suspicious and antagonistic. Vital for teamwork and customer service.
Neuroticism (Emotional Stability)
Tendency to experience unpleasant emotions easily (anxiety, anger, depression). Lower scores indicate higher emotional stability.
Update: The HEXACO Model
While Big 5 is standard, a newer model called HEXACO is gaining traction. It adds a sixth dimension: Honesty-Humility. This factor helps predict ethical behavior, integrity, and likelihood of workplace delinquency better than the Big 5 alone.
4. Does It Work? Predictive Validity
Psychometricians measure "Validity Coefficients" (r) from 0 (random) to 1 (perfect prediction). This chart compares how well different methods predict actual job performance.
r = 0.02
Handwriting analysis. Useless for prediction.
r ≈ 0.20
Weak predictor. Good for discussion, bad for hiring.
r = 0.41
Often based on Big 5/HEXACO traits. Strong predictor.
5. Accepted Applications
Recruitment & Selection
Goal: Predict job performance and tenure.
AVOID: MBTI, Enneagram (Legal risk due to low reliability).
Team Dynamics
Goal: Improve communication and empathy between colleagues.
NOTE: Lower validity tests like MBTI are acceptable here as "frameworks for conversation," not factual diagnosis.
Clinical Diagnosis
Goal: Diagnose pathology (disorders, narcissism, depression).
RESTRICTED: Administered only by licensed psychologists.