Psy 311: Methods 1

GOALS OF DEVELOPMENTAL

PSYCHOLOGY

Describe, explain, and optimize human development

Psy 311: Methods 2

GOALS OF DEVELOPMENTAL PSYCHOLOGY

1. DESCRIBE – characterize the behavior of human

beings of different ages and trace how it changes with age

– normal development & individual differences

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GOALS OF DEVELOPMENTAL PSYCHOLOGY

2. EXPLAIN– understanding why humans develop as

they do

– why people develop similarly & differently.

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GOALS OF DEVELOPMENTAL PSYCHOLOGY

3. OPTIMIZE– how people can be helped to develop

in a positive direction

– prevention & remediation

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METHODS OVERVIEW WHO: Sampling WHAT: Measures HOW: METHODS WHEN: DESIGN

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CHALLENGE TOLIFE-SPAN DEVELOPMENT

METHODS– How can we demonstrate causality?

– How can we study different pathways of development?

– How can we study changing people in a changing world?

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METHODS

TYPES OF METHODS– Correlational

– Experimental

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CORRELATIONAL METHOD

WHAT IS IT?– Looks at naturally existing relationships.

– Studies people who have already had experiences.

– Assigned “naturally” to groups.

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CORRELATIONAL METHOD (cont.)

DISADVANTAGES– Can’t prove cause-effect relations

between variables.• Could be the reverse effect.• Could be something else that causes

both variables.

A Teacher

Involvement

BChild’s

Motivation

CChild’sGender

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EXPERIMENTAL METHOD

WHAT IS IT?– 1. Random assignment of people to

“treatment” and “control” groups.

– 2. Manipulate the independent or “causal” variable.

– 3. Comparison groups are identical on everything but the treatment.

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EXPERIMENTAL METHOD (cont.)

ADVANTAGES– Can establish cause-effect relations

between variables.• Does show cause and effect.

–Does not rule out reverse relationship.

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EXPERIMENTAL METHOD (cont.)

DISADVANTAGES– “Treatment” may be artificial.

– May not work this way in the real world.

– “Can” cause vs. “does” cause.

– Lots of interesting causal variables cannot be manipulated.

Psy 311: Methods 15

CORRELATIONAL METHOD (cont.)

ADVANTAGES– Can be applied to data collected in

natural settings.

– Can be more applicable to the real world.

– Can be used to study issues that cannot be studied experimentally.

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EXPANDING METHODS (cont.)

CORRELATIONAL– Examining beginnings.

– Adding time sequences. EXPERIMENTAL

– Natural experiments.

– Optimizing interventions.

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DEVELOPMENTALDESIGNS

TYPES OF DESIGNS– Cross-Sectional

– Longitudinal

– Sequential

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CROSS-SECTIONAL DESIGN

WHAT IS IT?– At one time point.

– Look at people of different ages.

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CROSS-SECTIONAL DESIGN (cont.)

WHAT DO YOU GET?– Information about age differences.

Psy 311: Methods 20

CROSS-SECTIONAL DESIGN (cont.)

DISADVANTAGES– 1. Age differences may be COHORT

differences.

• BIRTH COHORTS: People of the same generation or born at about the same time.

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CROSS-SECTIONAL DESIGN (CONT)

DISADVANTAGES– 2. Provides no information about...

–how a person changes over time.

–how earlier experiences influence later development.

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LONGITUDINAL DESIGN

WHAT IS IT?– At many points in time; repeatedly

– Follow the same group of people

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LONGITUDINAL DESIGN (CONT)

WHAT DO YOU GET?– Information about age changes

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LONGITUDINAL DESIGN (cont.)

ADVANTAGES– 1. Actually can study how a person changes

over time.– 2. Actually can study how different people

change over time.– 3. Actually can study…

• how earlier developments are linked to later development.

• how earlier experiences influence later development.

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LONGITUDINAL DESIGN (cont.)

DISADVANTAGES– 1. Age changes may be HISTORICAL

changes.

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LONGITUDINAL DESIGN (cont.)

DISADVANTAGES– 2. Participants may be affected by

participation in study.• e.g., repeated testing

– 3. Participants may drop out.

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LONGITUDINAL DESIGN (cont.)

DISADVANTAGES– 4. Measures may later prove

inadequate.

– 5. Practical problems• time consuming • expensive

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CROSS-SECTIONAL DESIGN (cont.)

ADVANTAGES– 1. Does give information about age

differences.

– 2. Hints at developmental trends.

– 3. Practical.• takes little time to conduct• inexpensive.

Psy 311: Methods 29

SEQUENTIAL DESIGN

WHAT IS IT?– Combines cross-sectional and

longitudinal designs.

– Longitudinal studies on multiple generations or cohorts.

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SEQUENTIAL DESIGN (cont.)

WHAT DO YOU GET?– 1. Age differences and Cohort

differences.

– 2. Age changes and Historical changes.

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SEQUENTIAL DESIGN (Cont)

ADVANTAGES– 1. Compares development at different

historical periods

– 2. Compares development of different cohorts

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SEQUENTIAL DESIGN (Cont)

DISADVANTAGES– 1. Complex

– 2. Time consuming

– 3. Still only generalizable to the cohorts and historical periods you DID measure

– 4. You may find effects you do not want.

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DESIGNS FOR DEVELOPMENTAL QUESTIONS

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CROSS-SECTIONAL

Advantages– Age differences

– Suggests change

– Inexpensive, quick

Disadvantages– Age differences

could be cohort differences

– No information about change or effects of early experience

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LONGITUDINAL Advantages

– Age change

– How people develop differently

– Connections between early & later development

Disadvantages– Age change could

be historical change

– Expensive & long

– Drop out

– Repeated testing

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SEQUENTIAL

Advantages– Age changes

– Historical changes in development

Disadvantages– Really complex,

expensive & long

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WHAT IS THE BEST DEVELOPMENTAL DESIGN? Age differences

– CROSS-SECTIONAL• exploratory

Age changes– LONGITUDINAL

• effects of earlier experiences Historical changes

– SEQUENTIAL

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WHAT IS THE BEST DEVELOPMENTAL DESIGN

(CONT)?

Truly Developmental– LONGITUDINAL

Most Complete– SEQUENTIAL

Depends on the question

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LAST NAME, first name 1. Name the major problem with each

design: a) Correlational b) Experimental c) Cross-sectional d) Longitudinal e) Sequential

Psy 311: Methods 40

END