Personality Variables and Measurement Methods

Chapter 2Personality 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

Personality InventoryPlease 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)

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

Reliability (internal consistency) Cronbach’s alpha = .83Factor pattern Factor 1

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).

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.

Ace Davis (10) of Lexington, Kentucky and his prize-winning science project

Four possible causal structures of an A-B relationship AB 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 AB 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

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)

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 state experience measure On a 1 to 5 scale where 1 = not at all and 5 = extremely, rate the degree to which you are currently experiencing each of the following states: ____ anxious ____ confident ____ agitated ____ confused ____ serene ____ nervous ____ apprehensive ____ relaxed ____ calm

IQ tests are cognitive ability tests

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? not at all somewhat moderately very much 3. To what extent did you appear self-conscious during the conversation? not at all somewhat moderately very much

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? not at all somewhat moderately very much 3. To what extent did Participant A appear self-conscious during the conversation? not at all somewhat moderately very much

Observing and recording behavioral measures

A penile plethysmograph

Personality Variables and Measurement Methods