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Personality assessment, measurement, and research methods
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Chapter Outline

Sources of Personality Data

Self-Report Data (S-Data)
  • Information provided by a person, such as through a survey or interview
  • Individuals have access to a wealth of information about themselves that is inaccessible to anyone else
  • S-data personality tests
    • Unstructured items—open-ended
    • Structured items—response options provided
  • Limitations of S-data
    • People may not respond honestly
    • People may lack accurate self-knowledge
Observer-Report Data (O-Data)
  • Information provided by someone else about another person
  • Key features of O-data
    • Provide access to information not attainable through other sources
    • Multiple observers can be used to assess a person
  • Selecting observers
    • Professional personality assessors
    • People who actually know the target person
      • Often in better position to observe targetÕs natural behaviors than professional personality assessors
      • Allows for assessment of multiple social personalities
      • Because of relationship to target, however, observer may be biased
  • Naturalistic versus artificial observation
    • Naturalistic observation: Observers witness and record events that occur in the normal course of lives of the participants
    • Artificial observation: Occurs in artificial settings or situations
    • Naturalistic observation has the advantage of being able to secure information in realistic context, but at the cost of not being able to control events witnessed
    • Artificial observation has the advantage of controlling conditions and eliciting relevant behavior, but at the cost of sacrificing realism
  • Immediate versus retrospective observation
    • Immediate observation: Events observed and recorded as they happen
    • Retrospective observation: Events recorded after they have happened
  • Molar versus molecular units of observation
    • Size of the unit selected for observation
      • Molar: e.g., global traits of intelligence, emotional stability
      • Molecular: e.g., how fast a person walks
    • Smaller observational units are assessed with greater precision and greater between-observer agreement, but larger units are often more predictive of relevant outcomes
Test-Data (T-Data)
  • Information provided by standardized tests or testing situations
  • Idea is to see if different people behave differently in identical situations
  • Situation designed to elicit behaviors that serve as indicators of personality
  • Elicited behavior ÒscoredÓ without reliance on inference
  • Limitations
    • Participants might try to guess what trait is being measured and then alter their behavior to create certain impressions
    • Difficult to know if participants define testing situation as intended by experimenter
    • Researcher might influence how participants behave
  • Mechanical recording devices
    • ÒActometerÓ used to assess childrenÕs activity
    • Strengths
      • Not hampered by biases of human observer
      • May be used in naturalistic settings
    • Disadvantage: few personality dispositions lend themselves to mechanical assessment
  • Physiological data
    • Includes information about a personÕs level of arousal, reactivity to stimuliÑpotential indicators of personality
    • Key benefit is that it is difficult to fake responses
    • Disadvantages
      • Often used in artificial laboratory setting
      • Accuracy of recording hinges on whether participant perceives situation as experimenter intended
  • Projective Techniques
    • Person presented with ambiguous stimuli and asked to describe what she sees; assumption is that person ÒprojectsÓ personality onto ambiguous stimuli
    • Thematic Apperception Test
    • Rorschach Inkblot Test
    • Draw-a-Person Test
  • Strengths: May provide useful means for gathering information about wishes, desires, fantasies that a person is not aware of and could not report
  • Disadvantages: Difficult to score, uncertain validity, and reliability
    • Life-Outcome Data (L-Data)
      • Information that can be gleaned from events, activities, and outcomes in a personÕs life that is available for public scrutiny—e.g., marriage, speeding tickets
      • Can serve as important source of Òreal lifeÓ information about personality
      Issues in Personality Assessment
      • Links among different data sources—when they do and do not exist and how to interpret these linkages
      • Fallibility of personality measurement
        • All sources of data have limitations
        • Results that replicate through ÒtriangulationÓ (across different data sources) are most powerful
    Evaluation of Personality Measures
      • Degree to which measure represents ÒtrueÓ level of trait being measured
      • Types of reliability
        • Test-retest reliability: scores at one administration positively correlate with scores at second administration
        • Alternate forms reliability: scores on one version of test correlate with scores on parallel but different version of test
        • Internal consistency reliability: items within test positively correlate
      • Degree to which test measures what it claims to measure
      • Types of validity
        • Face validity: whether test appears to measure what it is supposed to measure
        • Predictive validity: whether test predicts criteria external to the test that it is expected to predict
        • Convergent validity: whether test score correlates with other measures that it should correlate with
        • Convergent validity: whether test score does not correlate with other measures it should not correlate with
        • Construct validity: subsumes other types of validity; broadest type of validity
  • Degree to which measure retains validity across different contexts, including different groups of people and different conditions
  • Generalizability subsumes reliability and validity
  • Greater generalizability not always better; what is important is to identify empirically contexts in which a measure is and is not applicable
  • Research Designs in Personality
      Experimental Methods
  • Used to determine causalityÑwhether one variable causes another Two key requirements:
  • Manipulation of variablesÑexperimenter manipulates independent variable and measures effects on dependent variable
  • Ensuring that participants in each experimental condition are equivalent to each otherÑaccomplished through random assignment
    • Correlational Studies
  • Correlation is a statistical procedure for determining whether there is a relationship between two variables
  • Designed to identify Òwhat goes with whatÓ in nature, and not designed to identify causal relationships
  • Major advantage is that it allows us to identify relationships among variables as they occur naturally
  • Correlation coefficient varies from Ð1 (perfect negative relationships) through 0 (no relationship) to +1 (perfect positive relationship)
  • Correlation does not indicate causation
  • Directionality problem
  • Third variable problem
    • Case Studies
  • In-depth examination of the life of one person
  • Advantages
  • Can find out about personality in great detail
  • Can give insights into personality that can be used to formulate a more general theory that is tested on a larger sample
  • Can provide in-depth knowledge about an outstanding figure, such as a political or religious figure
  • Disadvantages
  • Results based on the study of single person cannot be generalized to others
    • When to Use Experimental, Correlational, and Case Study Designs
  • Each design has strengths and weakness; strength of one is weakness of another
  • Which design a researcher uses depends on the research question and the goal of research
  • Taken together, three designs provide complementary methods for exploring personality
  • Summary and Evaluation
  • Decisions about data source and research design depend on the purpose of study
  • There is no perfect data source
  • There is no perfect research design
  • But some data sources and some methods are better suited for some purposes than for others