• Differentiate between types of research (descriptive, experimental, and correlational)
• Explain the strengths and weaknesses of different types of research (case studies, naturalistic observation, and surveys)
• Explain the strengths and weaknesses of different types of research (archival, longitudinal, and cross-sectional research)

Types of Research

Psychologists use a variety of research methods to understand, describe, and explain behavior—as well as the cognitive and biological processes that shape it.

Some methods involve direct observation, while others rely on surveys, interviews, or controlled experiments.

Each approach contributes to our understanding of human behavior but comes with its own strengths and limitations.

Three Main Categories of Psychological Research

Psychological research is typically grouped into three broad categories: descriptive, correlational, and experimental research.

1. Descriptive Research

Descriptive research focuses on observing and describing behavior without testing specific relationships between variables.

It helps psychologists gather rich, detailed information about what people do, think, or feel in a particular context.

• Example: A psychologist records how children interact on a playground to study peer influence without trying to change or control any behavior.
• Strength: Descriptive research is especially valuable when an experiment would be unethical, impractical, or premature.
• Limitations: Because it doesn’t test cause-and-effect relationships, it can be difficult to generalize findings to larger populations.

2. Correlational Research

Correlational research examines whether and how two or more variables are related.

Researchers collect data on these variables and analyze whether changes in one are associated with changes in the other.

• Example: Researchers explore whether students who eat breakfast perform better in morning classes.
• Strength: It allows researchers to identify meaningful relationships between variables in natural settings.
• Limitation: Correlation does not imply causation—even if two things occur together, one does not necessarily cause the other.

Correlational and experimental research both involve hypothesis testing, but descriptive research does not.

3. Experimental Research

Experimental research is the only method that can establish cause-and-effect relationships.

Researchers manipulate one or more independent variables and measure their effects on dependent variables, while controlling other factors that could influence the results.

• Example: Participants are randomly assigned to a sleep-deprived or well-rested group, then tested on a memory task. The researchers compare their performance to determine whether lack of sleep causes poorer memory.
• Strength: This method provides strong evidence for causal relationships.
• Limitations: Experiments can be conducted in artificial lab settings, raising questions about real-world applicability (known as ecological validity).

Some questions cannot be tested experimentally due to ethical concerns—for instance, exposing participants to harm or trauma.

Types of Research Overview

 

Table 1. Descriptive, Experimental, and Correlational Research
Research Design	Main Purpose	Example
Descriptive	Observes and describes behavior without testing relationships between variables	A psychologist observes children on a playground to study peer influence.
Correlational	Tests whether a relationship exists between two or more variables	Researchers examine the link between self-esteem and academic achievement.
Experimental	Determines whether one variable causes a change in another	Researchers test the effects of sleep deprivation on memory performance.

 

Each research type offers a unique lens for studying human behavior:

• Descriptive methods capture rich details of real life.
• Correlational methods reveal patterns and relationships.
• Experimental methods test cause and effect under controlled conditions.

In practice, psychologists often combine these approaches to strengthen their findings and ensure that results are both valid and applicable to real-world situations.

These next few pages will take a closer look at descriptive research methods—including case studies, naturalistic observation, and surveys—before exploring correlational and experimental designs in more detail.