Advanced Personality Theory and Assessment
Trait Taxonomies and Heritability
Beyond the Big Five: The HEXACO Model
While the Five-Factor Model (FFM) has dominated personality psychology, cross-cultural lexical studies support a six-factor structure. The HEXACO model adds 'Honesty-Humility' (H) as an independent dimension, which captures variance related to sincerity, fairness, greed avoidance, and modesty that is not fully explained by Agreeableness.
The Dark Triad of Personality
Individuals scoring extremely low on the Honesty-Humility factor of the HEXACO model are most likely to exhibit traits associated with:
Low Honesty-Humility is strongly correlated with the manipulative, deceitful, and self-serving behaviors characteristic of the Dark Triad (Narcissism, Machiavellianism, Psychopathy).
Correct answer: The Dark Triad
What formula calculates narrow-sense heritability by doubling the difference in correlation between monozygotic and dizygotic twins?
Falconer's formula is mathematically expressed as and is a foundational equation in classical twin studies for estimating genetic influence.
Correct answer: Falconer's formula
Biometric Variance Components (ACE Model)
| Component | Description |
|---|---|
| A (Additive Genetics) | Variance explained by the sum of individual genetic alleles. |
| C (Common Environment) | Environmental factors shared by siblings raised together (e.g., socioeconomic status). |
| E (Unique Environment) | Idiosyncratic experiences unique to one sibling, plus measurement error. |
Genome-Wide Association Studies (GWAS)
Modern behavioral genetics utilizes GWAS to identify specific single nucleotide polymorphisms (SNPs) associated with personality traits. Findings consistently show that personality traits are highly polygenic, meaning they are influenced by thousands of genetic variants, each contributing a minuscule effect size.