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Theoretical and measurement issues in trait psychology
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Chapter Outline

Theoretical and Measurement Issues in Trait Psychology

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
    • According to trait psychologists, every personality is the product of a combination of a few basic, primary traits
    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
    • How can there be consistency in a trait if it is known to change with age (e.g., impulsivity)? Focus on the rank order differences between people
    • Consistency Across Situations
      • Trait psychologists traditionally assumed cross-situation consistency
      • If situations mainly control how people behave, then the existence or relevance of traits questionable
      • Hartshorne and May (1928): Low cross-situation consistency is in honesty, helpfulness, self-control
      • Mischel (1968): Personality psychologists should abandon their efforts to explain behavior with traits, focusing instead on situations
      • Situationism: If behavior varies across situations, then situational differences and not personality traits determine behavior
      • Mischel's (1968) critique encouraged debate in personality psychology about the importance of traits compared to situations in causing behavior
      • Both sides tempered views: Trait psychologists acknowledged the importance of situation, and situationists acknowledged the importance of traits
      • Debate led to two lasting changes: Focus on person-situation interaction and practice of aggregation
    Person-Situation Interaction
    • Two possible explanations for behavior:
      • Behavior is a function of personality traits
      • Behavior is a function of situation
    • Integration: Personality and situation interact to produce behavior
      • Differences between people make a difference only under certain circumstances
      • Situational specificity: Certain situations can provoke behavior that is out of character for an individual
      • Strong situation: Situations in which most people react in a similar way (e.g., grief following loss of loved one)
      • When situations are weak or ambiguous, personality has its strongest influence
    • Three additional ways in which personality and situation interact to produce behavior
      • 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
    • Longer tests are more reliable than shorter ones and are better measures of traits
    • Single behavior or occasion may be influenced by extenuating circumstances unrelated to personality
    • Aggregation implies that traits are only one influence on behavior
    • Aggregation also implies that traits refer to the person's average level
    • Thus, personality psychologists will never be good at predicting single acts or single occasions
Measurement Issues
  • Trait approach relies on self-report surveys to measure personality
  • Personality psychologists assume that people differ in the amounts of various traits, and so a key measurement issue is determining how much of trait person has
  • Traits are often represented as dimensions along which people differ
  • Trait psychologists are aware of and address circumstances that affect accuracy, reliability, validity, and utility of self-report trait measures
  • Carelessness
    • Method for detecting such problems is an infrequency scale embedded in test
    • Infrequency scale contains items that most people answer in a particular way
    • If a participant answers differently than most, this suggests carelessness
    • Another method for detecting carelessness is to include duplicate items spaced far apart in the survey—if the person answers the same item differently, this suggests carelessness
    Faking on Questionnaires
    • "Fake goodÓ: Attempt to appear better off or better adjusted than one is
    • "Fake badÓ: Attempt to appear worse off or less adjusted than one is
    • Method to detect is to a devise scale that, if answered in particular way, suggests faking
    Response Sets
    • Extreme responding: Tendency to give endpoint responses
    • Social desirability: Tendency to answer items in such a way so that one comes across as socially attractive or likable
    • Two views on social desirability:
      • Represents distortion and should be eliminated or reduced
        • Resolved by (1) measuring and statistically removing, (2) designing surveys that are less susceptible to this response set, or (3) using forced-choice format
          • Valid part of other desirable personality traits, such as agreeableness, and should be studied
        • Self-deceptive optimism versus impression management
Personality and Prediction
  • Whether someone does well in an employment setting may be determined, in part, by whether a person's personality traits mesh with job requirements
  • Personality traits may predict who is likely to do well in particular job, so it makes sense to select people for employment based on measures of traits
  • But using tests to select employees has limitations and potential liabilities
  • Lawsuits have challenged the use of tests on the grounds ranging from discrimination, to invasion of privacy, to freedom of religion
  • Most employers receive overall test scores, however, not the applicant's answers to specific questions
  • In 1978, the EEOC standardized federal guidelines for the use of tests in employment selection
  • Two main concerns that the employer must satisfy to use for employment selection
    • Test must predict performance on a specific job or jobs like the one people are being selected for
    • Test must not be biased or have "undue impactÓ on persons from protected groups, such as women and minorities
    Personnel selection: Choosing the Right Person for Job as Police Officer
    • Personality tests frequently used to screen out "wrongÓ individuals from a pool of applicants for police officers
    • Educational selection: The Graduate Record Examination (GRE) and Success in Graduate School
      • Most graduate schools require applicants to take the GRE, and most schools use GRE scores to some degree in deciding whom to accept into program
      • GRE is an aptitude test, thought to reflect intelligence or the capacity to learn
      • Many studies have been conducted to assess the degree to which GRE scores predict success in psychology graduate school
      • Meta-analyses reveal that GRE scores do predict success in graduate school, but correlations are only modest (.15 to .40)
      • Four arguments for why GRE scores can be useful, even though they only modestly predict success in graduate school
        • Even small increments in predictability above chance can be useful
        • Costs of failing to select the right people into graduate school can be high
        • GRE scores can be useful if used with appropriate criterion (i.e., what want to predict)
          • Criterion problem: Concerns how we define and measure the criterion we want to predict
          • Validity of GRE depends on which criterion used to define success in graduate school—if defined as obtaining Ph.D., GRE scores are valid predictors
        • Research indicates that, without range restriction, correlations between GRE scores and success in graduate school are high, ranging from .30 to .70
      • Range restriction affects correlation
        • When two variables are correlated with each other, the size of correlation depends, in part, on whether each variable spans full range in the sample
        • Violation occurs when participants are selected on the basis of one score, and then that score is correlated with another variable on which participants have been measured
        • Correlation between two variables will shrink as the range of scores on one (or both) variables is restricted
      A Closer Look: Integrity Tests
      • Integrity tests are surveys designed to assess whether a person is generally honest or dishonest; replaced polygraph
      • When assessed against the "big fiveÓ personality traits, integrity is the combination of high conscientiousness, high agreeableness, and low neuroticism
      • Integrity tests can be a valuable addition to other measures used in employment selection
Summary and Evaluation
  • Hallmark of trait perspective is the emphasis on the differences between people
  • Traits psychologists assume that people will be relatively constant over time and across situations in behaviors, because of their differences in various traits
  • Traits are more likely to influence a person's behavior when the situation is weak and ambiguous and doesn't push for conformity from all people
  • Personality traits refer to the average tendencies in behavior
  • Trait psychologists are interested in the accuracy of measurement
  • Interest in measurement and prediction has led trait psychologists to apply these skills to the selection or screening of job applicants and other situations where personality might make a difference