Personality Psychology: Research Methods, Assessment, and Traits

Hippocrates

Personality linked to balance of bodily fluids ('humors').

Pythagoras

Personality determined by season of birth.

Formal study

Only ~100 years old.

Predicts important outcomes

Examples include job performance, health, relationships.

Helps improve environments

Applicable in education, workplaces, therapy.

Challenges assumptions

Examples include 'opposites attract' and 'absence makes the heart grow fonder.'

Experiments

Research method involving manipulation of variables.

IV (Independent Variable)

What researcher manipulates.

DV (Dependent Variable)

What researcher measures/what may change.

Hypothesis

Testable educated guess.

Confounds

Other variables that explain results, solved with random assignment.

Correlational Studies

Examine relationships as they occur in nature without manipulation.

Positive correlation

Both variables increase together.

Negative correlation

One variable increases while the other decreases.

Correlation coefficient

Ranges from -1 to +1 indicating strength and direction.

Advantages of Correlational Studies

Easier, cheaper, practical when manipulation is impossible.

Disadvantages of Correlational Studies

No cause-and-effect conclusions.

Case Studies

In-depth study on one person, useful for rare phenomena.

Limitation of Case Studies

Hard to generalize, no comparison group.

Self-report

Methods include interviews, questionnaires, experience sampling.

Observer reports

Gathered from friends, family, strangers.

Lab tasks

Examples include aggression paradigm, BART, marshmallow test.

Physiological data

Includes HR, skin conductance, EEG, lie detectors.

Projective tests

Examples include Rorschach, TAT, sentence completion.

Life outcome data

Major life events such as marriage, divorce, jobs.

Reliability

Consistency in measurement.

Test-retest reliability

Stability of results over time.

Inter-rater reliability

Agreement among raters.

Validity

Accuracy in measuring what it should.

Predictive validity

Forecasts future outcomes.

Concurrent validity

Matches established tests.

Key point about reliability and validity

Reliability is necessary for validity, but not sufficient.

IRB

Protects human participants.

Exempt

No risk, no vulnerable groups.

Expedited

Minimal risk.

Full review

More than minimal risk/vulnerable populations.

IACUC

Ensures animal welfare.

Ethical guidelines

Informed consent, confidentiality, right to withdraw.

Deception

Only if necessary + debriefing required.

Safety plans

For sensitive research.

Carelessness

Fix with duplicate/infrequency items.

Faking

Good (look better) or Bad (look worse). Fix: Social desirability checks or fake symptom items.

Response sets

Yea-saying, nay-saying, extreme responding. Fix: Reverse-coded items.

Barnum Effect

Vague personality statements apply to anyone.

Illusory Correlation

Believing two rare events are related (due to selective attention).

Base Rates

People ignore actual probabilities when interpreting traits.

Traits

Stable across time and situations.

Single Trait

Focus on one trait (e.g., self-esteem).

Many Trait

Start with outcome, then examine many predictors.

Essential Trait

Narrow down the 'core' traits.

Theoretical approach

Guided by theory.

Lexical approach

All important traits are in language.

Statistical (Factor Analysis)

Groups correlated traits into clusters.

Big Five (OCEAN)

1. Openness - imaginative, curious. 2. Conscientiousness - organized, disciplined. 3. Extraversion - sociable, energetic. 4. Agreeableness - cooperative, trusting. 5. Neuroticism - emotional instability, stress-reactive.

Typological Approach

Places people into categories (e.g., Myers-Briggs, Caspi).

Criticisms of Typological Approach

Low reliability, low predictive validity, arbitrary cut-offs.

Correlation

No cause & effect.

Case study

Depth not breadth.