Chapter 2 Personality Research Methods

Measuring personality variables What is a variable? What kinds of variables are there? Categorical variables (examples: gender, political affiliation) Continuous variables (height, weight) How can we measure an aspect of personality as a variable? Psychometrics (psyche – mind, metric – measure): an applied branch of psychology that deals with psycho-logical measurement The most commonly used approach to study human personality: the self-report questionnaire measure

I am socially somewhat awkward. Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives: a. very much unlike me b. somewhat unlike me c. somewhat like me d. very much like me I am socially somewhat awkward. I don’t find it hard to talk with strangers I feel tense when I’m with people I don’t know well. When conversing I worry about saying something dumb. I feel nervous when speaking to someone in authority. I am often uncomfortable at parties and other social functions. I feel inhibited in social situations. I have trouble looking someone right in the eye. I am more shy with members of the opposite sex.

Correlating variables Correlating two variables Measure the two variables (X and Y) as accurately as necessary Plot the variables as X-Y coordinates on a two-dimensional space Examine the shape of the “scatterplot” to estimate the size and “direction” of the resulting correlation Compute the correlation coefficient using the correct mathematical formula (or let the computer do it for you)

NAME HEIGHT (X) WEIGHT (Y) Allport, Allen 69 175 Bimiup, Scotty 68 159 Brewer, Joseph 71 177 Derrickson, Derek 150 Dorman, Carlton 67 162 Horne, Karyn 65 134 Ingram, Irene 64 121 James, Jocelyn 125 Jones, Ernie 158 Lang, Fred 161 Kelly, Christine 63 119 Lime, Nora 128 etc.

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

I am socially somewhat awkward. Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives: a. very much unlike me b. somewhat unlike me c. somewhat like me d. very much like me I am socially somewhat awkward. I don’t find it hard to talk with strangers I feel tense when I’m with people I don’t know well. When conversing I worry about saying something dumb. I feel nervous when speaking to someone in authority. I am often uncomfortable at parties and other social functions. I feel inhibited in social situations. I have trouble looking someone right in the eye. I am more shy with members of the opposite sex.

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Item-to-total correlations SHY1 SHY2 SHY3 SHY4 SHY5 SHY6 SHY7 SHY8 SHY9 SHY .68 .64 .67 .65 .73 .75 .57 .61

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Reliability (internal consistency) Cronbach’s alpha = Reliability (internal consistency) Cronbach’s alpha = .83 Factor pattern Factor 1 SHY1 .69 SHY2 .62 SHY3 .67 SHY4 .66 SHY5 .65 SHY6 .75 SHY7 .78 SHY8 .54 SHY9 .58

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

I am socially somewhat awkward. Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives: a. very much unlike me b. somewhat unlike me c. somewhat like me d. very much like me I am socially somewhat awkward. I don’t find it hard to talk with strangers I feel tense when I’m with people I don’t know well. When conversing I worry about saying something dumb. I feel nervous when speaking to someone in authority. I am often uncomfortable at parties and other social functions. I feel inhibited in social situations. I have trouble looking someone right in the eye. I am more shy with members of the opposite sex.

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Example of concurrent validity Correlate the participants’ total shyness score for the 9-item measure of shyness (X variable) with their rating on the following dimensional scale (Y variable): In general, how shy are you? _________________________________________________________ 0 10 20 30 40 50 60 70 80 90 100 If both X and Y are good alternative ways to measure shyness, the correlation between X and Y should be positive and large (for example, r = .86).

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Example of convergent and discriminant validity Correlate the participants’ total shyness score for the 9-item measure of shyness (X variable) with their total scores on the following other personality measures: Shyness score correlated with: Social anxiety .91 Introversion .66 Conscientiousness .15 IQ .03 The first two correlations provide evidence of the shyness measure’s convergent validity. The last two correlations provide evidence of the shyness measure’s discriminant validity.

Reliability and validity in personality measurement Reliability (consistency of measurement) Internal consistency Item-to-total correlation Split-half reliability Cronbach’s alpha Test-retest reliability Validity (construct validity) Face validity Concurrent validity Convergent and discriminant validity Criterion (predictive) validity

Four possible causal structures of an A-B relationship A B Changes in Variable A cause corresponding changes to occur in Variable B B A Changes in Variable B cause corresponding changes to occur in Variable A A B Changes in Variable A cause changes in Variable B, which in turn cause changes in Variable A, which in turn . . . A Changes in Variable C cause corresponding changes in both C Variables A and B. Variables A and B therefore covary even B though neither one causes the other

Three categories of moderating variables in personality research Category Function Representative Example Situational moderating variables Specify in which types of situations traits will be good versus poor predictors of their trait-relevant behaviors Psychologically weak versus strong situations Personal moderating variables Specify for which types of people traits will be good versus poor predictors of their trait-relevant behaviors Private self-consciousness Criterion moderating variables Specify the types of behaviors that traits will predict either well or poorly Level of aggregation of the behavioral measure

Experimental study Correlational study Goal Variables Criteria Test for a causal relationship between a manipulated variable and a measured variable Test for a correlational relationship between two measured variables Variables Independent variable (manipulated) Dependent variable (measured) Predictor variable (measured) Criterion variable (measured) Criteria Experimenter controls the IV Random assignment to conditions Measures of both the predictor and the criterion variables must be obtained Major pitfalls Confounded manipulation of the independent variable Confounded measurement of the dependent variable Using a measured variable that is unreliable or that lacks validity Confounded measurement of the predictor variable Confounded measurement of the criterion variable Using measured variables that are unreliable or that lack validity Possible conclusions Level of IV affects level of DV Level of IV doesn’t affect level of DV PV is related to (associated with) CV PV is not related to CV Best safeguard Replication

Methods for measuring aspects of personality Trait measures (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings of behavior (e.g., self-ratings of one’s own behavior) Objective ratings of behavior (e.g., observer ratings of one’s behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

I am socially somewhat awkward. Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives: a. very much unlike me b. somewhat unlike me c. somewhat like me d. very much like me I am socially somewhat awkward. I don’t find it hard to talk with strangers I feel tense when I’m with people I don’t know well. When conversing I worry about saying something dumb. I feel nervous when speaking to someone in authority. I am often uncomfortable at parties and other social functions. I feel inhibited in social situations. I have trouble looking someone right in the eye. I am more shy with members of the opposite sex.

Methods for measuring aspects of personality Trait inventories (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings (e.g., self-ratings of behavior) Objective ratings (e.g., observer ratings of behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

Example of a Mood Adjective Check List Check all of the following adjectives that describe your current mood: ____ anxious ____ confident ____ agitated ____ confused ____ serene ____ nervous ____ apprehensive ____ relaxed ____ calm OR . . . To what extent do you feel anxious? 0 1 2 3 not at all slightly moderately extremely

Methods for measuring aspects of personality Trait inventories (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings (e.g., self-ratings of behavior) Objective ratings (e.g., observer ratings of behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

IQ tests are cognitive ability tests

Methods for measuring aspects of personality Trait inventories (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings (e.g., self-ratings of behavior) Objective ratings (e.g., observer ratings of behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

Subjective self-ratings of behaviors 1. To what extent did you take the lead during the conversation? not at all somewhat moderately very much 2. To what extent did you disclose personal information during the conversation? 3. To what extent did you appear self-conscious during the conversation?

Observing and rating people’s behavior

Objective observer ratings of behaviors 1. To what extent did Participant A take the lead during the conversation? not at all somewhat moderately very much 2. To what extent did Participant A disclose personal information during the conversation? 3. To what extent did Participant A appear self-conscious during the conversation?

Methods for measuring aspects of personality Trait inventories (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings (e.g., self-ratings of behavior) Objective ratings (e.g., observer ratings of behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

Observing and recording behavioral measures

Methods for measuring aspects of personality Trait inventories (e.g., self-report questionnaires) State experience measures (e.g., mood ratings) Ability tests (e.g., intelligence test) Subjective ratings (e.g., self-ratings of behavior) Objective ratings (e.g., observer ratings of behavior) Behavioral measures (e.g., counts of specific behaviors) Physiological measures (e.g., galvanic skin response)

A penile plethysmograph