Transcript Scientific study of people Two major issues: 1. Measurement of personality –how do we know what a person’s personality is?? ► Will depend on.

Scientific study of people
Two major issues:
1. 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.)
2.
Scientific study of personality – theory
development relies on process of research
Sources of information
1.
Observer ratings – measure comes from
someone other than the person being assessed
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2.
Self-reports – person who is being assessed
indicates what they think they are like
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Interviews, observations of behavior, judgments
Called O-data
Called S-data
Can have different types of each – will discuss a
variety of measures shortly
Measurement
1.
Subjective – requires interpretation
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2.
Requires reliability rating – would two raters agree?
Objective – not dependent on a judgment
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Often numerical: Likert scale, reaction time, etc.
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
Measurement
Subjective assessment
► Measurement that relies on interpretation
► Weaknesses
 Different observes may make different judgments
► Strengths
 Complex phenomena may be examined and valuable
insight gained
Measurement
Objective measurement
► Weaknesses
 May reduce a complex behavior
 May fail to capture all of the important or
interesting phenomena
► Strengths
 Clear and consistent (reliable)
Reliability
= 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
Types of reliability
1.
Internal consistency = reliability within a
particular set of observations
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ACT: would expect people to do about the same on first half
and second half (split-half reliability)
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Increases as we take repeated measures
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i.e. a function of number of relevant items (the more the
better, but also need to be realistic)
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Cronbach’s coefficient alpha
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The average of all possible split-half correlations
Should be about .8 or higher
Types of reliability
2.
test-retest reliability = the measure’s
degree of consistency on different
occasions
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Stability over time – measuring device should be
stable
Example: GRE scores are stable over time. Don’t
want GRE scores to fluctuate greatly
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
Validity
► Measurements
mean nothing
can be highly reliable but
See colorquiz
http://www.colorquiz.com
Validity
Are you measuring what you think you are measuring?
Construct validity – does the measure capture the conceptual
idea?
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Long process to establish construct validity:
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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
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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.
Validity
► 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.”
Biases that impact validity
1.
Response sets – readiness to answer in a
particular way
a. Acquiescence – tendency to say “yes” or agree
b. Social desirability – people tend to want to
portray themselves in a positive light
► Some traits are not neutral: honest/dishonest
Biases that impact validity
1.
Experiment bias
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2.
Ethnic bias – fails to take into account the
relevant culture of person being tested
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3.
E.g. self-esteem/strengths
Gender bias – expectations based on gener
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4.
Experimenter bias
Experimenter expectancies
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
Types of personality measures
1.
Self-report measures
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Usually pencil and paper tests
Most common type of test
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Examples:
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Minnesota Multiphasic Personality Inventory (MMPI)
Big-Five Inventory (BFI)
Types of personality measures
2.
Q-sort
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Person makes comparisons among their own
characteristics
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Uses a stack of cards with various
characteristics
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Individual places cards into piles indicating
how descriptive it is of him or her
Types of personality measures
Judgments by others
3.
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Someone else answers questions about the person
being measured
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Some traits are easier to judge than others
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Example: extraversion
Motives may be more difficult to judge
Can use ratings from parents, teachers, friends,
spouses, psychologists, etc.
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Example: Terman’s longitudinal study of smart kids
Types of personality measures
4.
Biological measures
 Assumes that the nervous system is an
important element of personality
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Modern Biological Measures
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Electroencephalogram (EEG)
Positron emission topography (PET) scan
Magnetic resonance imagery (MRI)
Hormonal levels
Chromosomal analysis
Types of personality measures
Types of personality measures
5.
Behavioral observations
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Records the actual behavior of a person
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Types of behavioral observations
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Simply counting a specific behavior
Coding videotaped interactions
Electronic pagers
Types of personality measures
6.
Interviews
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Unstructured interviews
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Typically yield rich information, but validity is questionable
Structured interviews
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More valid, but usually do not reveal individual nuances
Types of personality measures
7.
Document analysis/life stories
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Involves the careful analysis of writings such as
letters and diaries
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Can be a very rich source of information
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Examples:
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Allport’s “Letters from Jenny”
Diary of Anne Frank
Types of personality measures
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Projective tests
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Uses an unstructured stimulus, task, or situation
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The goal is to gain access to unconscious motives and
concerns
Examples:
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Draw-a-person
Rorschach Inkblot
Thematic Apperception Test (TAT)
Projective tests
Projective tests
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