Scientific study of people Two major issues: 1. Measurement of personality –how do we know what a...

Scientific study of peopleScientific study of people

Two major issues:Two major issues:1.1. Measurement of personalityMeasurement of personality –how do we –how do we

know what a person’s personality is??know what a person’s personality is??► Will depend on what we think is important Will depend on what we think is important

and our assumptions about personality (can and our assumptions about personality (can we self-report, etc.)we self-report, etc.)

2.2. Scientific study of personalityScientific study of personality – theory – theory development relies on process of development relies on process of researchresearch

Sources of informationSources of information

1.1. Observer ratings – measure comes from Observer ratings – measure comes from someone other than the person being someone other than the person being assessedassessed► Interviews, observations of behavior, judgmentsInterviews, observations of behavior, judgments► Called O-dataCalled O-data

2.2. Self-reports – person who is being assessed Self-reports – person who is being assessed indicates what they think they are likeindicates what they think they are like► Called S-dataCalled S-data

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

MeasurementMeasurement

1.1. Subjective – requires interpretationSubjective – requires interpretation► Requires reliability rating – would two raters Requires reliability rating – would two raters

agree?agree?

2.2. Objective – not dependent on a Objective – not dependent on a judgmentjudgment► Often numerical: Likert scale, reaction time, Often numerical: Likert scale, reaction time,

etc.etc.

Subjective measurementsSubjective measurements

► Example: pirate test for children (in book)Example: pirate test for children (in book)► Birthday party test: 2 year olds running Birthday party test: 2 year olds running

wildly in a gymwildly in a gym Measure activity levelMeasure activity level Measure introversion/extroversionMeasure introversion/extroversion Measure adaptability to new Measure adaptability to new

situations/fearfulnesssituations/fearfulness

= subjective because they require our = subjective because they require our interpretationinterpretation


Subjective assessmentSubjective assessment►Measurement that relies on interpretationMeasurement that relies on interpretation

►WeaknessesWeaknesses Different observes may make different Different observes may make different

judgmentsjudgments

► StrengthsStrengths Complex phenomena may be examined and Complex phenomena may be examined and

valuable insight gainedvaluable insight gained


Objective measurementObjective measurement

►WeaknessesWeaknesses May reduce a complex behavior May reduce a complex behavior May fail to capture all of the important or May fail to capture all of the important or

interesting phenomenainteresting phenomena

►StrengthsStrengths Clear and consistent (reliable)Clear and consistent (reliable)

ReliabilityReliability

= consistency or repeatability of a measure= consistency or repeatability of a measure

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

Reliable measures are preciseReliable measures are precise Low reliability includes errorLow reliability includes error

Example: measuring for window blindsExample: measuring for window blinds

Types of reliabilityTypes of reliability

1.1. Internal consistencyInternal consistency = reliability within a = reliability within a particular set of observationsparticular set of observations► ACT: would expect people to do about the same on ACT: would expect people to do about the same on

first half and second half (split-half reliability)first half and second half (split-half reliability)

► Increases as we take repeated measuresIncreases as we take repeated measures

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

► Cronbach’s coefficient alphaCronbach’s coefficient alpha The average of all possible split-half correlationsThe average of all possible split-half correlations

► Should be about .8 or higherShould be about .8 or higher


2.2. test-retest reliabilitytest-retest reliability = the measure’s = the measure’s degree of consistency on different degree of consistency on different occasionsoccasions► Stability over time – measuring device should Stability over time – measuring device should

be stablebe stable► Example: GRE scores are stable over time. Example: GRE scores are stable over time.

Don’t want GRE scores to fluctuate greatlyDon’t want GRE scores to fluctuate greatly


3. 3. Inter-rater reliabilityInter-rater reliability = in observer = in observer ratings, the person making the rating ratings, the person making the rating is the measuring device. Raters who is the measuring device. Raters who agreeagree Example: scores on gymnastics or ice Example: scores on gymnastics or ice

skating eventsskating events

ValidityValidity

►Measurements can be highly reliable Measurements can be highly reliable but mean nothingbut mean nothing

See colorquiz See colorquiz

http://http://www.colorquiz.comwww.colorquiz.com

ValidityValidity

Are you measuring what you think you are measuring?Are you measuring what you think you are measuring?

Construct validityConstruct validity – does the measure capture the – does the measure capture the conceptual idea?conceptual idea?

► Long process to establish construct validity:Long process to establish construct validity: The assessment is related to what is should be related to = The assessment is related to what is should be related to =

convergent validationconvergent validation The assessment is NOT related to what it should not be related The assessment is NOT related to what it should not be related

to = to = divergent validationdivergent validation► Example: loveExample: love

Conceptual definition: a strong caring and affection for another Conceptual definition: a strong caring and affection for another personperson

How do I How do I operationalizeoperationalize this (make this concrete and this (make this concrete and measurable)measurable)

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

ValidityValidity

►Criterion-related validationCriterion-related validation – does our – does our measure predict an outcomemeasure predict an outcome

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

►Content validityContent validity = is a test measuring = is a test measuring the domain it is supposed to be the domain it is supposed to be measuringmeasuring In a personality test, am I measuring In a personality test, am I measuring

“personality” or am I measuring “mood.”“personality” or am I measuring “mood.”

Biases that impact validityBiases that impact validity

1.1. Response sets – readiness to answer Response sets – readiness to answer in a particular wayin a particular way

a.a. AcquiescenceAcquiescence – tendency to say “yes” or – tendency to say “yes” or agreeagree

b.b. Social desirabilitySocial desirability – people tend to want – people tend to want to portray themselves in a positive lightto portray themselves in a positive light► Some traits are not neutral: honest/dishonestSome traits are not neutral: honest/dishonest

Biases that impact validityBiases that impact validity

1.1. Experiment biasExperiment bias► Experimenter biasExperimenter bias► Experimenter expectanciesExperimenter expectancies

2.2. Ethnic bias – fails to take into account the Ethnic bias – fails to take into account the relevant culture of person being testedrelevant culture of person being tested► E.g. self-esteem/strengthsE.g. self-esteem/strengths

3.3. Gender bias – expectations based on generGender bias – expectations based on gener► characteristic that is seen as a strength in one group characteristic that is seen as a strength in one group

is seen as a weakness in anotheris seen as a weakness in another

4.4. Barnum effect – tendency to believe vague Barnum effect – tendency to believe vague generalities about one’s personalitygeneralities about one’s personality

Types of personality Types of personality measuresmeasures

1.1. Self-report measuresSelf-report measures Usually pencil and paper testsUsually pencil and paper tests Most common type of testMost common type of test

► Examples: Examples: Minnesota Multiphasic Personality Inventory (MMPI)Minnesota Multiphasic Personality Inventory (MMPI) Big-Five Inventory (BFI)Big-Five Inventory (BFI)


2.2. Q-sortQ-sort Person makes comparisons among their Person makes comparisons among their

own characteristicsown characteristics

Uses a stack of cards with various Uses a stack of cards with various characteristicscharacteristics

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


3.3. Judgments by othersJudgments by others Someone else answers questions about the Someone else answers questions about the

person being measuredperson being measured

Some traits are easier to judge than othersSome traits are easier to judge than others► Example: extraversion Example: extraversion ► Motives may be more difficult to judgeMotives may be more difficult to judge

Can use ratings from parents, teachers, friends, Can use ratings from parents, teachers, friends, spouses, psychologists, etc.spouses, psychologists, etc.► Example: Terman’s longitudinal study of smart kidsExample: Terman’s longitudinal study of smart kids


4.4. Biological measuresBiological measures Assumes that the nervous system is Assumes that the nervous system is

an important element of personalityan important element of personality

► Modern Biological MeasuresModern Biological Measures Electroencephalogram (EEG)Electroencephalogram (EEG) Positron emission topography (PET) scanPositron emission topography (PET) scan Magnetic resonance imagery (MRI)Magnetic resonance imagery (MRI) Hormonal levelsHormonal levels Chromosomal analysisChromosomal analysis


5.5. Behavioral observationsBehavioral observations Records the actual behavior of a personRecords the actual behavior of a person

► Types of behavioral observationsTypes of behavioral observations Simply counting a specific behaviorSimply counting a specific behavior Coding videotaped interactionsCoding videotaped interactions Electronic pagersElectronic pagers


6.6. InterviewsInterviews

► Unstructured interviewsUnstructured interviews Typically yield rich information, but validity is Typically yield rich information, but validity is

questionablequestionable

► Structured interviewsStructured interviews More valid, but usually do not reveal individual More valid, but usually do not reveal individual

nuancesnuances


7.7. Document analysis/life storiesDocument analysis/life stories► Involves the careful analysis of writings such Involves the careful analysis of writings such

as letters and diariesas letters and diaries

► Can be a very rich source of informationCan be a very rich source of information

► Examples:Examples: Allport’s “Letters from Jenny”Allport’s “Letters from Jenny” Diary of Anne FrankDiary of Anne Frank


8.8. Projective testsProjective tests► Uses an unstructured stimulus, task, or Uses an unstructured stimulus, task, or

situationsituation The goal is to gain access to unconscious motives The goal is to gain access to unconscious motives

and concernsand concerns

► Examples:Examples: Draw-a-personDraw-a-person Rorschach InkblotRorschach Inkblot Thematic Apperception Test (TAT)Thematic Apperception Test (TAT)

Projective testsProjective tests


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

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

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