Psychology 3051 Psychology 305B: Theories of Personality Lecture 2.

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Psychology 305B: Theories of Personality

Lecture 2

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Scoring your questionnaire:

1. Reverse score items 3, 5, 8, 9, and 10.

5 14 2

3 = 32 41 5

2. Sum scores across 10 items.

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Lecture 2Questions That Will be Answered in Today’s Lecture

5. How is research used to test theories? (continued)

6. What types of measures are used to assess personality?

7. How are the reliability and validity of personality measures assessed?

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3. Quasi-experimental studies

Designed to contrast pre-existing groups on a variable of interest.

Like correlational studies, quasi-experimental studies do not allow researchers to determine causality.

The variable is not manipulated; instead, naturally-occurring groups are compared on the

variable of interest.

How is Research Used to Test Theories? (continued)

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In contrast to correlational studies, however, quasi-experimental studies do not use the full range of scores on the variable of interest; rather, categories of participants are compared.

The use of categories can result in the loss of information and reduce the validity of research findings.

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Subject Depression GroupNumber Score

6 3 Low9 28 Low1 30 Low

10 49 Low4 50 Low

---------------------------- Median Split --------------------------2 51 High5 53 High8 67 High3 75 High7 88 High

Example of loss of information associated with categorization:

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4. Case Studies

Involve the in-depth examination of the life of one person.

Assessment techniques include: ObservationInterviews Administration of standard personality testsAnalysis of written text

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Ted Bundy, 1946 - 1989

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Exercise: Application of Research Methods

Construct: Happiness.

Possible operationalizations:

• Measure of life satisfaction.

• Measure assessing the frequency and intensity with which participants experience positive emotions (e.g., joy, contentment, excitement).

• Number of times participants smile.

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People experience happiness when they have successfully influenced others’ opinions.

Experimental study.

Hypothesis Ideal Research Method

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Group A

Group B

Random Assignment

Treatment A

Posttest

A Simple Experiment

Treatment B

Posttest

Pretest

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People experience happiness when they have successfully influenced others’ opinions.

People who report extraordinarily high levels of happiness exhibit a unique constellation of personality characteristics.

People who experience high levels of happiness tend to be more optimistic.

Experimental study.

Case study.

Correlational study or quasi-experimental study.

Hypothesis Ideal Research Method

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What types of measures are used to assess personality?

There are three types of personality measures.

1. Personality Measures that Rely Upon Self-Report Data (S-Data)

• Most common method used for measuring personality.

• Data are provided by the participant.

• Data are collected through interviews or questionnaires; questionnaires are most commonly used.

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• Unstructured questionnaires require participants to complete open-ended fill-in-the-blank items.

• There are 2 types of questionnaires: Unstructured and structured.

E.g. Twenty Statements Test: Participants complete the statement “I am” 20 times.

Coding for a given personality characteristic involves counting the number of statements that refer to that characteristic.

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• Structured questionnaires require participants to complete items with limited response options.

E.g., True/false items: I like loud and crowded parties ………… T/FI enjoy trying new foods …………………. T/F

E.g., Adjective checklists: adventurous

conservative

E.g., Adjectives or statements accompanied by rating scales:

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Using the scale below, indicate how descriptive you believe each of the following traits is of you. Circle the appropriate number to the right of each trait.

1 2 3 4 5Not at all Somewhat Highly

descriptive descriptive descriptive

1. Adventurous 1 2 3 4 52. Ambitious 1 2 3 4 53. Broad-minded 1 2 3 4 54. Conservative 1 2 3 4 55. Extroverted 1 2 3 4 5

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Using the scale below, please indicate how much you disagree or agree with the following statements. Circle the appropriate number to the right of each statement.

1 2 3 4 5Strongly Neutral Stronglydisagree agree

1. I feel that I’m a person of worth, at least on an equal basis with others …………………………….. 1 22. I feel that I have a number of good qualities …….. 1 23. All in all, I am inclined to feel that I am a failure …. 1 24. I am able to do things as well as most people …… 1 2

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• Rosenberg’s Self-Esteem Scale

Score by reversing “negatively-keyed” items and summing responses to 10 items.

Measures global feelings of self-worth.

Mean score for university undergraduates: 38, SD = 6.2.

Females tend to score slightly lower than males.

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The participant can report on his/her private experiences (e.g., emotions, desires, beliefs).

• Advantages of S-Data:

Inexpensive.

The participant can report on his/her personality across diverse contexts; allows for general characteristics to be assessed.

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The participant’s responses may be biased (e.g., the participant may exaggerate positive attributes and/or minimize negative attributes).

• Disadvantages of S-Data:

The participant may lack sufficient self-insight to accurately respond to the items.

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2. Personality Measures that Rely Upon InformantData (I-Data)

• Typically, informants are asked to complete structured questionnaires similar to those described for S-Data.

• Data are provided by individuals who are well acquainted with the participant.

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• Advantages of I-Data:

Informants can report on characteristics that the participant may be unaware of (e.g., social reputation).

Informants’ judgments provide an assessment of the participant’s characteristics in natural settings.

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Informants’ judgments are often limited to specific contexts and, therefore, do not allow for the

participant’s general characteristics to be assessed.

• Disadvantages of I-Data:

Informants are unaware of many of the participant’s private experiences (e.g., emotions, desires,

beliefs).

Informants’ judgments may be biased (e.g., a mother may overlook the negative attributes and emphasize the positive attributes of her child).

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3. Personality Measures that Rely Upon BehaviouralData (B-Data)

• Data may be collected in either natural settings or laboratory settings.

• Data are collected through the researcher’s direct observation of the participant.

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• Advantages of B-data collected in natural settings:

(a) Natural settings:

The observations provide an assessment of the participant’s characteristics in naturally-

occurring situations.

• The researcher observes the participant engage in his/her daily activities (e.g., observes

the participant at home, has the participant complete a daily diary).

The data are not subject to the biases inherent in S-data and I-data.

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• Disadvantages of B-data collected in natural settings:

Events that the researcher wishes to observe may not occur.

Costly.

The presence of the researcher may influence the participant’s behaviour.

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• The researcher observes the participant in the laboratory.

(b) Laboratory settings:

• Three types of B-data are collected in the laboratory:

1. The participant’s overt behavioural reactions.

2. The participant’s covert physiological reactions (e.g., heart rate, galvanic skin response,

muscle contraction).

3. The participant’s responses to projective tests (e.g., Rorschach Ink Blot Test).

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Example of the Rorschach Ink Blot Test:

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• Advantages of B-data collected in laboratory settings:

The data are not subject to the biases inherent in S-data and I-data.

Allows the researcher to control extraneous influences on the participant’s behaviour.

Allows the researcher to observe the participant’s reactions to events that are not

likely to occur in natural settings.

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• Disadvantages of B-data collected in laboratory settings:

The results are difficult to generalize to naturally-occurring situations.

The presence of the researcher may influence the participant’s behaviour.

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How are the reliability and validity of personality

• In order to accurately assess a given personality characteristic, the measure that is used (whether it is based on S-, I-, or B-data) must be both reliable and valid.

Refers to the consistency with which a measure assesses a given construct across repeated measurements.

• Reliability

measures assessed?

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Method for increasing the reliability of a measure:

Theoretically, the error associated with one assessment should cancel out the error associated with another assessment.

Include multiple assessments of the construct of interest within the measure.

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Thus, for measures that rely upon

(a) S-data: Include more than one item.

(b) I-data: Include more than one item and/or use more than one informant.

(c) B-data: Make more than one observation and/or use more than one observer.

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1. I like to work alone rather than in groups.

2. I keep a schedule every day.

3. I tend to seek out leadership roles.

4. I never leave a task unfinished.

5. I’m a bad loser.

6. Hard work pays off in the long run.

7. I feel my best is never good enough.

8. I have high expectations for myself.

9. I continually strive for excellence.

10. It’s important for me to know I’m doing my best.

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The reliability of a measure is assessed in one of three ways.

1. Internal consistency:

• Relevant for multi-item questionnaires (S- or I- data).

• Reflects the degree to which the items that comprise the questionnaire are consistent with one another (i.e., tap the same

underlying construct).

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(b) Cronbach’s alpha reliability coefficient: Involves calculating the correlation between

each pair of items and averaging the resulting correlations; most common method for

assessing internal consistency; acceptable alpha for a questionnaire > .75.

• The internal consistency of a questionnaire is assessed in one of two ways:

(a) Split-half reliability coefficient: Involves splitting the items in half and calculating the correlation between participants’ scores on the two halves.

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2. Inter-rater reliability:

• Relevant for studies in which two or more individuals rate the participant on a given characteristic or behaviour (S-, I-, or B-data).

• In the case of S-data, the raters are coders scoring participants’ responses to interviews or unstructured questionnaires; in the case of I-data, the raters are informants; in the case of B-data, the raters are researchers.

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• Reflects the degree to which the scores provided by different raters are consistent with one another (i.e., the degree to which there is consensus among the raters).

• Involves calculating the correlations between the scores provided by different raters.

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3. Test-retest reliability:

• Relevant for all types of measures (S-, I-, or B-data).

• Reflects the degree to which the scores participants obtained in one test administration

are consistent with the scores they obtained in a second test administration (i.e., the stability of

participants’ scores across time).

• Involves calculating the correlation between the scores participants obtained in the first testadministration and the scores they obtained in the second test administration.

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Refers to the degree to which a measure assesses the construct it is intended to measure.

• Validity (or Construct Validity)

A measure that is reliable may or may not be valid; a reliable measure may bear no

relationship to the construct it was intended to measure.

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The validity of a measure may be established by demonstrating that it possesses one or more of

the following forms of validity.

1. Face validity:

• Refers to the degree to which a measure appears to tap the construct under study.

• E.g., The items from Rosenberg’s Self-Esteem Scale appear to have face validity.

All in all, I am inclined to feel that I am a failureOn the whole, I am satisfied with myself

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2. Content validity:

• Refers to the degree to which a measure assesses the underlying dimensions of theconstruct under study.

• E.g., Self-esteem

Rosenberg’s Self-Esteem Scale: Assumes self-esteem is unidimensional.

Harter’s Self-Perception Profile: Assumes self-esteem is multidimensional; assesses self-esteem related to scholastic competence, athletic competence, social acceptance, physical appearance and behavioural conduct.

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• Content validity is assessed in one of two ways:

(a) By having experts judge the adequacy with which the measure assesses the underlying dimensions of the construct.

(b) In the case of questionnaire measures, factor analyzing participants’ responses to the items.

Factor analysis is a statistical procedure that identifies items that are highly correlated with one another; each group of highly correlated items is thought to reflect a single dimension of the construct under study.

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3. Predictive validity (or criterion validity):

• Refers to the degree to which a measure is able to predict the likelihood or extremity of a

behaviour (i.e., a criterion) that is theoretically related to the construct under study.

• E.g., A self-esteem measure that is high in predictive validity should be able to predict: alcohol and drug use persistence in the face of failure number of sexual partners (i.e., sexual promiscuity)

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4. Convergent validity:

• Refers to the degree to which a measure relates to measures that assess conceptually similar constructs (i.e., constructs that are theoretically related to the construct of interest).

• E.g., A self-esteem measure that is high in convergent validity should be correlated with measures of: depression neuroticism negative affectivity

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5. Discriminant validity:

• Refers to the degree to which a measure does not relate to measures that assess conceptually dissimilar constructs (i.e., constructs that are not theoretically related to the construct of interest).

• E.g., A self-esteem measure that is high in discriminant validity should not be correlated with measures of:

agreeableness need for cognition political attitudes (i.e., liberal vs. conservative)

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• Often, convergent and discriminant validity are examined simultaneously; this is a powerful method by which to demonstrate the validity of a measure.

• E.g., Results of a study that simultaneously examined the convergent and discriminant validity of a self-esteem measure:

Dep Neur NegAff Agree NCogn Polatt

SE -.68 -.57 -.63 .06 .09 -.02

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5. How is research used to test theories? (continued)

6. What types of measures are used to assess personality?

7. How are the reliability and validity of personality measures assessed?

Questions That Were Answered in Today’s Lecture