Designing Research » Natural Experiments

What you'll learn this session

Study time: 30 minutes

What natural experiments are and how they differ from other research methods
The key characteristics and features of natural experiments
The strengths and limitations of using natural experiments
Real-world examples of natural experiments in psychology
How to evaluate natural experiments in exam questions

Introduction to Natural Experiments

Natural experiments are a unique type of research method where researchers study the effects of naturally occurring events or situations that they didn't create or control. Unlike laboratory experiments where researchers manipulate variables, natural experiments take advantage of real-world circumstances that create different conditions for different groups of people.

Key Definitions:

Natural experiment: A research method where researchers observe the effects of naturally occurring events or situations that create different conditions for different groups.
Independent variable (IV): The variable that occurs naturally and isn't manipulated by the researcher.
Dependent variable (DV): The outcome that is measured to see if the natural IV had an effect.
Control group: People who weren't exposed to the natural event or situation.
Experimental group: People who were exposed to the natural event or situation.

🔬 Key Features of Natural Experiments

Natural experiments have several important features:

Researchers don't manipulate the IV - it happens naturally
Participants aren't randomly allocated to conditions
The research takes place in real-world settings
Researchers measure the effects after the event has occurred
They often involve comparing groups who experienced different conditions

💡 When Are Natural Experiments Used?

Psychologists use natural experiments when:

It would be unethical to manipulate the variable (e.g., studying trauma)
It's impossible to manipulate the variable (e.g., gender, age)
The situation is rare or unique (e.g., effects of a disaster)
They want to study behaviour in real-world settings
They're interested in long-term effects that would be difficult to study in a lab

Natural Experiments vs. Other Research Methods

Understanding how natural experiments compare to other research methods helps us see their unique place in psychological research:

🔬 Lab Experiments

Lab Experiments: Researchers control and manipulate variables in an artificial setting.

Natural Experiments: Researchers observe the effects of naturally occurring events in real-world settings.

📄 Correlational Studies

Correlational Studies: Look for relationships between variables without establishing cause and effect.

Natural Experiments: Can suggest cause and effect because one group experiences something the other doesn't.

👥 Field Experiments

Field Experiments: Researchers manipulate variables in a real-world setting.

Natural Experiments: No manipulation by researchers - they study what naturally happened.

Strengths of Natural Experiments

Natural experiments offer several advantages that make them valuable for psychological research:

👍 Advantages

High ecological validity: They study real-world events and behaviours, making findings more applicable to everyday life.
Ethical approach: Researchers don't need to expose participants to potentially harmful situations.
Unique insights: They allow study of situations that couldn't be created in a lab (like disasters or major life events).
Stronger than correlational studies: They can suggest cause and effect relationships.
Often longitudinal: They can track effects over long periods of time.

👎 Limitations

Lack of control: Researchers can't control extraneous variables that might affect results.
No random allocation: Groups may differ in important ways besides the natural event.
Difficult to replicate: Natural events often can't be repeated for further study.
Retrospective data: Often relies on memories or records from after the event.
Ethical issues: Studying people affected by traumatic events raises ethical concerns about potential distress.

Famous Natural Experiments in Psychology

Let's look at some real examples of natural experiments that have contributed to our understanding of psychology:

📑 Case Study: The Czech Twins Study

Researchers: Cyril Burt and colleagues

Natural IV: Twins raised together vs. twins separated at birth

DV: IQ scores and personality traits

Findings: This study examined twins who were separated at birth and raised in different environments. Despite growing up in different families, identical twins showed remarkable similarities in IQ and personality, suggesting a strong genetic component to these traits. This natural experiment provided evidence for the nature side of the nature-nurture debate.

Evaluation: The study provided unique insights that would be impossible to gain through a controlled experiment (we can't randomly separate twins!). However, the separated twins often ended up in similar socioeconomic environments, which is an extraneous variable.

📑 Case Study: Effects of Romanian Orphanages

Researchers: Michael Rutter and the ERA team

Natural IV: Early institutional deprivation vs. normal upbringing

DV: Cognitive development, attachment and social functioning

Background: After the fall of the Romanian government in 1989, thousands of children were found in severely deprived orphanages. Some were later adopted by UK families.

Findings: Children who spent longer in the orphanages showed more developmental problems, attachment issues and cognitive delays. However, many showed remarkable recovery after adoption, especially those adopted before 6 months of age.

Significance: This natural experiment provided crucial evidence about the effects of early deprivation and the potential for recovery, which would be unethical to study through experimental manipulation.

Designing and Evaluating Natural Experiments

When psychologists use natural experiments, they need to carefully consider several factors:

✅ Good Practice in Natural Experiments

Careful selection of comparison groups: Try to find groups that are as similar as possible except for the natural event.
Control for extraneous variables: Identify and account for other factors that might explain differences.
Use standardised measures: Ensure the DV is measured consistently and objectively.
Consider ethical implications: Be sensitive when studying people affected by traumatic events.
Acknowledge limitations: Be clear about what the study can and cannot tell us.

📝 Exam Tips for Evaluating Natural Experiments

When answering exam questions about natural experiments, remember to:

Identify the natural IV and DV in the study
Explain why a natural experiment was appropriate (usually ethical or practical reasons)
Discuss both strengths (ecological validity, ethical approach) and limitations (lack of control, possible confounding variables)
Consider whether the findings can suggest a causal relationship
Evaluate whether the comparison groups were well-matched

Applying Your Knowledge

Understanding natural experiments helps us evaluate psychological research and think critically about claims regarding cause and effect. Here are some ways to apply this knowledge:

Evaluating news stories: When you hear about research in the news, consider whether it was a natural experiment and what that means for the conclusions we can draw.
Understanding social policy: Many social policies are based on natural experiments (e.g., studies of the effects of poverty or education changes).
Thinking about your own experiences: Consider how major events (like the COVID-19 pandemic) create natural experiments that psychologists might study.

💡 Modern Example: COVID-19 as a Natural Experiment

The COVID-19 pandemic created numerous natural experiments for psychologists to study:

Effects of school closures on children's learning and mental health
Impact of lockdowns on family relationships and domestic violence
Changes in work patterns and productivity with remote working
Differences in mental health outcomes between countries with different pandemic responses

These studies help us understand the psychological impact of major societal disruptions without researchers having to create these conditions (which would be impossible and unethical).

Summary: Key Points About Natural Experiments

Natural experiments are a valuable research method in psychology that allow researchers to study the effects of naturally occurring events or situations. They offer high ecological validity and allow the study of variables that couldn't be manipulated ethically or practically. However, they lack the control of laboratory experiments and can't establish causation as definitively.

When evaluating natural experiments, consider the selection of comparison groups, potential confounding variables and the ethical implications of the research. Understanding natural experiments helps us critically evaluate psychological research and appreciate the complex relationship between real-world events and human behaviour.

🧠 Test Your Knowledge!