Personality Traits and Measurement Notes

Personality Psychology: Traits and Measurement

Learning Objectives

  • Identification of the most important traits.
  • Discussion of the five-factor model of personality.
  • Discuss the various theoretical and measurement issues in trait psychology.

Trait – Descriptive Adjectives

  • Words that describe traits, or attributes of a person that are characteristic of a person and perhaps enduring over time.
  • Two Basic Formulations:
    • Traits as Internal Causal Properties
    • Traits as Purely Descriptive Summaries
Traits as Internal Causal Properties
  • Traits are presumed to be internal in the sense that individuals carry their desires, needs, and wants from one situation to the next (Alston, 1975).
  • Furthermore, these desires and needs are assumed to be causal in the sense that they explain the behaviour of the individuals who possess them.
  • Psychologists who view traits as internal dispositions do not equate traits with external behaviour.
  • The scientific usefulness of viewing traits as causes of behaviour lies in ruling out other causes.
Traits as Purely Descriptive Summaries
  • Proponents of this alternative formulation define traits simply as descriptive summaries of attributes of persons; they make no assumptions about internality or causality (Hampshire, 1953; Saucier & Goldberg, 2001).
  • The important point is that those who view traits as descriptive summaries do not prejudge the cause of someone’s behaviour.
  • They merely use traits to describe the trend in a person’s behaviour.

Identification of the Most Important Traits: Three Approaches

  • Lexical Approach
    • All traits listed and defined in the dictionary form the basis for describing differences among people (Allport & Odbert, 1936)
  • Statistical Approach
    • Uses factor analysis, or similar statistical procedures, to identify major personality traits
  • Theoretical Approach
    • Researchers rely on theories to identify important traits
Lexical Approach
  • Starts with lexical hypothesis: All important individual differences have become encoded within the natural language
  • People find these trait terms helpful in describing people and for communicating information about them.
  • Two criteria for identifying important traits:
    • Synonym frequency
      • The more important such an attribute, the more synonyms and subtly distinctive facets of the attribute will be found within any one language (Saucier & Goldberg, 1996).
    • Cross-cultural universality
      • The more important is an individual difference in human transactions, the more languages will have a term for it (Goldberg, 1981).
  • Problem and limitation:
    • Many traits are ambiguous, metaphorical, obscure, or difficult
    • Personality is conveyed through different parts of speech (not just adjectives), including nouns and adverbs
  • Strength:
    • The lexical strategy has proven to be a remarkably generative starting point for identifying important individual differences (Ashton & Lee, 2005).
    • Good starting point for identifying important individual differences, but should not be the exclusive approach used
Statistical Approach
  • Starts with a large, diverse pool of personality items
  • Most researchers using the lexical approach turn to the statistical approach to basic categories of traits
  • The goal of the statistical approach is to identify major dimensions of personality
  • Factor analysis * Useful in reducing the large array of diverse traits into a smaller, more useful set of underlying factors.
    • Factor loading: Index of how much of a variation in an item is “explained” by a factor
    • Cautionary note: initial selection of items
Example of Factor Analysis:

Factor 1 (Extraversion): Adjectives with high loadings include Humorous (.66), Amusing (.65), and Popular (.57).
Factor 2 (Ambition): Adjectives with high loadings include Hard-working (.63), Productive (.52), and Determined (.52).
Factor 3 (Creativity): Adjectives with high loadings include Imaginative (.62), Original (.53), and Inventive (.47).

Note: The numbers refer to factor loadings, which indicate the degree to which an item correlates with the underlying factor.
Source: Adapted from Matthews & Oddy, 1993.

Theoretical Approach
  • The theoretical approach to identifying important dimensions of individual differences starts with a theory that determines which variables are important.
  • Example: to a self-actualization theorist such as Maslow (1968), it is critical to measure individual differences in the degree to which people are motivated to self-actualize
  • Its strengths coincide with the strengths of the theory.
  • If we have a powerful theory that tells us which variables are important, then it saves us from wandering.
  • At the same time, its weaknesses coincide with the weaknesses of the theory.
  • To the extent that the theory contains gaps or biases, the subsequent identification of important individual differences will reflect omissions and distortions.

Evaluating the Approaches for Identifying Important Traits

  • In practice, many personality researchers use a combination of three approaches
  • Norman (1963) and Goldberg (1990) started with the lexical strategy to identify the first set of variables for inclusion
  • Then used factor analysis to reduce the set to a more manageable number (five or six)

Five-Factor Model

  • Five broad factors: Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness/Intellect
Empirical Evidence for the Five-Factor Model
  • Replicable in studies using English language trait words as items
  • Found by more than a dozen researchers using different samples
  • Can be replicated: different languages, factors, items, stable over time

Theoretical and Measurement Issues in Trait Psychology

  • Meaningful Differences Between Individuals
  • Consistency Over Time
  • Consistency Across Situations
  • Person-Situation Interaction
  • Aggregation
Meaningful Differences Between Individuals
  • There are meaningful differences between individuals (traits psychology is also called differential psychology)
  • People differ in amounts of traits, and differences can be accurately measured
Consistency Over Time
  • Research indicates consistency over time for broad traits
  • Although consistent over time, how a trait is manifested in behavior might change over time
Consistency Across Situations
  • Trait psychologists traditionally assumed cross-situation consistency
  • Situationism: If behavior varies across situations, then situational differences and not personality traits determine behavior
  • If situations mainly control how people behave, then the existence or relevance of traits is questionable
  • e.g.: Hartshorne and May (1928): Low cross-situation consistency in honesty, helpfulness, self-control
Person-Situation Interaction
  • Situational specificity: Certain situations can provoke behavior that is out of character for an individual
  • Strong situation: Situations in which most people react similarly (e.g., grief following the loss of a loved one)
  • Traits are more likely to influence a person’s behavior when the situation is weak and ambiguous.
  • Selection: Tendency to choose or select situations in which one finds oneself, as a function of personality
  • Evocation: Certain personality traits may evoke specific responses from others
  • Manipulation: Various means by which people influence the behavior of others; tactics of manipulation vary with personality will be elaborated further in Chapter 11
Aggregation
  • Number of items
  • Single behavior or occasion may be influenced by extenuating circumstances unrelated to personality
  • Personality traits – average tendencies in behavior

Measurement Issues

  • The trait approach relies on self-report surveys to measure personality
  • Traits are often represented as dimensions along which people differ
  • Trait psychologists are aware of and address circumstances that affect the accuracy, reliability, validity, and utility of self-report trait measures
  • Carelessness * If a participant answers differently than most, this suggests carelessness
    • Faking on Questionnaires
      • “Fake good”
      • “Fake bad”
    • Response Sets
      • Acquiescence: Tendency to agree with items, regardless of content; reverse-keying some items
      • Extreme responding: Tendency to give endpoint responses
      • Social desirability: Tendency to answer items in such a way that one comes across as socially attractive or likable
    • Integrity Testing: A Closer Look
      • Integrity tests are surveys designed to assess whether a person is generally honest or dishonest; replaced polygraph
Addressing Measurement Issues
  • Social Desirability Scales: Include items designed to detect socially desirable responses (e.g., "I never tell a lie"). Unrealistic agreement suggests faking good or overly positive self-presentation.
  • Infrequency Scales: Add items unlikely to be endorsed (e.g., "I have flown to the moon"). Endorsing them indicates random responding or faking.
  • Use Validated Measures
  • Combine questionnaire data with behavioral observations, interviews, or other assessment methods to ensure consistency across different measures. Cross-Validation
  • Use techniques that allow respondents to answer sensitive questions indirectly, reducing the pressure to fake responses. Randomized Response Techniques
  • Pattern Analysis: Analyse response patterns for inconsistencies or improbably extreme scores.
  • Person-Item Fit Statistics : Identify responses that do not align with expected patterns based on normative data. Use Statistical Techniques

Personality and Prediction

  • Use in employment
  • But using tests to select employees has limitations and potential liabilities
  • Lawsuits have challenged the use of tests on grounds ranging from discrimination to the invasion of privacy to freedom of religion
  • Two main concerns:
  • Test must predict performance
  • Test must not be biased or have “undue impact” on persons from protected groups, such as women and minorities