Lecture 5: Psychobiological & lexical approaches

Lexical Methodologies

• Terms used to distinguish people based on their behavior
• Terms that describe common behaviors (e.g., walking, digesting) are excluded
• Four categories of terms:
  • Censorial and evaluative (e.g., insignificant, acceptable, worthy)
  • Metaphorical (e.g., red-headed, lean)

Problem of Lexical Accounts

• Lexical accounts of personality describe traits, but don't explain them
• Questions to be answered:
  • Why do we behave in and experience the world as we do?
  • What is the source of individual differences in behavior and experience?

Psychobiological Methodologies

• Hans Eysenck: 'Father' of modern biological approaches to personality
• Assumptions:
  • Personality develops through the interplay between:
    • Cognition (memory, perception, thought, language, intelligence)
    • Temperament (characteristic, biologically-based reaction patterns)
    • Constitution or physiology (neurology, endocrinology, genetics, etc.)
    • Environment (both human and physical)
  • Personality is dimensionally and hierarchically arranged

Two Main Trait Taxonomies

• Lexical taxonomy (e.g., Big-5):
  • Seeks to identify personality trait-descriptors in natural language
  • Five dimensions:
    • Neuroticism: emotional stability
    • Extraversion: social/interpersonal impact
    • Agreeableness: quality of social/interpersonal impact
    • Conscientiousness: responsibility, dutifulness, and will to achieve
    • Openness: artistic tendencies, intellect, and acceptance of new ideas or change
• Psychobiological taxonomy (Eysenck's Big-3):
  • Seeks to identify biological/genetic markers of personality traits
  • Three dimensions:
    • Neuroticism (related temperament: emotionality): predisposition to mood and anxiety disorders
    • Extraversion (related temperament: activity): predisposition to accidents, injuries, and substance abuse
    • Psychoticism (tough- vs. avoidance)

Assumptions of the Trait Approach

• Common assumptions:
  • The personality space is made up of dimensions
  • These dimensions are finite
  • We can discover these dimensions by categorizing lexical evidence and biological data
  • These dimensions are linear and independent from each other

Dimensionality: Linearity and Independence

• Dimensionality: linearity is assumed, but in reality, dimensions are likely oblique and non-linear
• Independence: examined whether extraversion (E) and neuroticism (N) are independent except amongst high N scorers

Contributions of the Trait Approach

• Scientific theories that are evidence-based
• Clear-cut and reliable predictions
• Testable and probabilistic
• Cross-cultural (also gender/age) validity
• Direct applications to occupational/educational psychology, psychopathology, and evolutionary psychology
• Contributions to criminal profiling and adaptive interrogation techniques

Limitations of the Trait Approach

• Can't manage complex, dynamic interactions between elements of personality
• Statistical methods of analysis assume linearity and independence
• Lexical approach can't identify what personality traits are
• Biological approach is generally unreliable
• How to account for changes in personality traits through adulthood?
• Theoretically weak