Scientific study of people
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Scientific study of people. Two major issues: Measurement of personality –how do we know what a person’s personality is?? Will depend on what we think is important and our assumptions about personality (can we self-report, etc.)

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Scientific study of people

Two major issues:

  • Measurement of personality –how do we know what a person’s personality is??

    • Will depend on what we think is important and our assumptions about personality (can we self-report, etc.)

  • Scientific study of personality – theory development relies on process of research

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Sources of information

  • Observer ratings – measure comes from someone other than the person being assessed

    • Interviews, observations of behavior, judgments

    • Called O-data

  • Self-reports – person who is being assessed indicates what they think they are like

    • Called S-data

  • Can have different types of each – will discuss a variety of measures shortly

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    • Subjective – requires interpretation

      • Requires reliability rating – would two raters agree?

  • Objective – not dependent on a judgment

    • Often numerical: Likert scale, reaction time, etc.

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    Subjective measurements

    • Example: pirate test for children (in book)

    • Birthday party test: 2 year olds running wildly in a gym

      • Measure activity level

      • Measure introversion/extroversion

      • Measure adaptability to new situations/fearfulness

        = subjective because they require our interpretation

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    Subjective assessment

    • Measurement that relies on interpretation

    • Weaknesses

      • Different observes may make different judgments

    • Strengths

      • Complex phenomena may be examined and valuable insight gained

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    Objective measurement

    • Weaknesses

      • May reduce a complex behavior

      • May fail to capture all of the important or interesting phenomena

    • Strengths

      • Clear and consistent (reliable)

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    = consistency or repeatability of a measure

    • Once you have one measurement about someone, how confident can you be that you will get the same measurement the second and third time

    • Reliable measures are precise

    • Low reliability includes error

      Example: measuring for window blinds

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    Types of reliability

    • Internal consistency = reliability within a particular set of observations

      • ACT: would expect people to do about the same on first half and second half (split-half reliability)

      • Increases as we take repeated measures

      • i.e. a function of number of relevant items (the more the better, but also need to be realistic)

      • Cronbach’s coefficient alpha

        • The average of all possible split-half correlations

      • Should be about .8 or higher

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    Types of reliability

    • test-retest reliability = the measure’s degree of consistency on different occasions

      • Stability over time – measuring device should be stable

      • Example: GRE scores are stable over time. Don’t want GRE scores to fluctuate greatly

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    Types of reliability

    3. Inter-rater reliability = in observer ratings, the person making the rating is the measuring device. Raters who agree

    • Example: scores on gymnastics or ice skating events

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    • Measurements can be highly reliable but mean nothing

      See colorquiz

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    Are you measuring what you think you are measuring?

    Construct validity – does the measure capture the conceptual idea?

    • Long process to establish construct validity:

      • The assessment is related to what is should be related to = convergent validation

      • The assessment is NOT related to what it should not be related to = divergent validation

    • Example: love

      • Conceptual definition: a strong caring and affection for another person

      • How do I operationalize this (make this concrete and measurable)

      • Could use a rating scale, intensity of eye contact, measure behaviors, etc.

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    • Criterion-related validation – does our measure predict an outcome

      • E.g. does our “love test” predict which couples will get married?

  • Content validity = is a test measuring the domain it is supposed to be measuring

    • In a personality test, am I measuring “personality” or am I measuring “mood.”

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    Biases that impact validity

    • Response sets – readiness to answer in a particular way

      • Acquiescence – tendency to say “yes” or agree

      • Social desirability – people tend to want to portray themselves in a positive light

        • Some traits are not neutral: honest/dishonest

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    Biases that impact validity

    • Experiment bias

      • Experimenter bias

      • Experimenter expectancies

  • Ethnic bias – fails to take into account the relevant culture of person being tested

    • E.g. self-esteem/strengths

  • Gender bias – expectations based on gener

    • characteristic that is seen as a strength in one group is seen as a weakness in another

  • Barnum effect – tendency to believe vague generalities about one’s personality

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    Types of personality measures

    • Self-report measures

      • Usually pencil and paper tests

      • Most common type of test

        • Examples:

          • Minnesota Multiphasic Personality Inventory (MMPI)

          • Big-Five Inventory (BFI)

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    Types of personality measures

    • Q-sort

      • Person makes comparisons among their own characteristics

      • Uses a stack of cards with various characteristics

      • Individual places cards into piles indicating how descriptive it is of him or her

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    Types of personality measures

    • Judgments by others

      • Someone else answers questions about the person being measured

      • Some traits are easier to judge than others

        • Example: extraversion

        • Motives may be more difficult to judge

      • Can use ratings from parents, teachers, friends, spouses, psychologists, etc.

        • Example: Terman’s longitudinal study of smart kids

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    Types of personality measures

    • Biological measures

      • Assumes that the nervous system is an important element of personality

        • Modern Biological Measures

          • Electroencephalogram (EEG)

          • Positron emission topography (PET) scan

          • Magnetic resonance imagery (MRI)

          • Hormonal levels

          • Chromosomal analysis

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    Types of personality measures

    • Behavioral observations

      • Records the actual behavior of a person

        • Types of behavioral observations

          • Simply counting a specific behavior

          • Coding videotaped interactions

          • Electronic pagers

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    Types of personality measures

    • Interviews

      • Unstructured interviews

        • Typically yield rich information, but validity is questionable

      • Structured interviews

        • More valid, but usually do not reveal individual nuances

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    Types of personality measures

    • Document analysis/life stories

      • Involves the careful analysis of writings such as letters and diaries

      • Can be a very rich source of information

      • Examples:

        • Allport’s “Letters from Jenny”

        • Diary of Anne Frank

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    Types of personality measures

    • Projective tests

      • Uses an unstructured stimulus, task, or situation

        • The goal is to gain access to unconscious motives and concerns

      • Examples:

        • Draw-a-person

        • Rorschach Inkblot

        • Thematic Apperception Test (TAT)

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    Types of personality measures

    Method used depends on questions being asked and type of information needed and available

    See chart in book on strengths and weaknesses, p. 58