Types of Validity Psych: Definitions, Examples & How to Improve Them
In psychology, validity refers to whether a test, method, or experiment actually measures what it claims to measure.
There are several types of validity that help researchers judge how accurate, realistic, and meaningful their findings are.
This guide breaks down the main types of validity in psychology — with examples, how to improve each one, and how they appear in A-level Psychology exams.
What Is Validity in Psychology?
Definition:
Validity is the extent to which a psychological test or study measures what it intends to measure.
If a test or experiment has high validity, it accurately reflects the concept being studied.
If it has low validity, the results may be misleading or not generalisable.
Why Validity Matters in Psychology
Validity ensures that psychological findings are trustworthy and useful in the real world.
Without it, even well-designed experiments can produce inaccurate or biased conclusions.
That’s why psychologists use control techniques such as
-
Counterbalancing
to reduce bias and improve validity.
The 4 Types of Validity in Psychology
Psychologists often divide validity into four main types:
1️⃣ Internal Validity
2️⃣ External Validity
3️⃣ Construct Validity
4️⃣ Criterion Validity
Each one helps determine how strong and meaningful the research findings are.
1️⃣ Internal Validity
Definition:
Internal validity refers to whether changes in the dependent variable are genuinely caused by the independent variable — not by other factors.
Example:
If participants perform better on a memory test after caffeine, internal validity means caffeine — not fatigue or time of day — caused the change.
Threats to internal validity include:
How to improve internal validity:
-
Use control groups
-
Randomly allocate participants
-
Standardise instructions and settings
2️⃣ External Validity
Definition:
External validity is the extent to which results can be generalised beyond the study itself — to other people, settings, or times.
There are three main subtypes:
-
Ecological Validity – can findings apply to real-world settings?
-
Population Validity – can findings apply to other groups of people?
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Temporal Validity – do results remain true over time?
Example:
A memory test on university students may not apply to older adults — meaning it has low population validity.
📚 Read more about ecological realism here:
👉 Ecological Validity in Psychology
How to improve external validity:
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Use diverse, representative samples
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Conduct research in natural settings
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Replicate studies across times and cultures
3️⃣ Construct Validity
Definition:
Construct validity is how well a test or measure truly represents the concept it claims to assess.
Example:
A questionnaire measuring anxiety should actually assess anxiety — not stress, introversion, or worry.
How to improve construct validity:
-
Use established psychological scales
-
Check results against theoretical definitions
-
Pilot-test questionnaires before full studies
4️⃣ Criterion Validity
Definition:
Criterion validity measures how well one test predicts or correlates with a related outcome.
Example:
If an IQ test accurately predicts school grades or job performance, it has high criterion validity.
Subtypes of criterion validity:
-
Concurrent Validity – how well a test correlates with an existing measure
-
Predictive Validity – how well a test forecasts future outcomes
How to improve criterion validity:
-
Compare results with trusted assessments
-
Collect long-term follow-up data
One effective way to improve validity is through clear and consistent measurement. See how this works in Operationalisation in Psychology.
Validity vs Reliability
Validity and reliability are closely related but not the same.
| Feature | Validity | Reliability |
|---|---|---|
| What it measures | Accuracy | Consistency |
| Key question | Does it measure what it claims? | Would it produce the same result again? |
| Example | A valid IQ test measures intelligence | A reliable test gives similar results each time |
Both are needed for high-quality research.
You can have a reliable but invalid test — e.g., a broken scale that gives the same wrong weight every time!
While validity ensures accuracy, reliability in psychology focuses on consistency. Both are essential for producing credible psychological research.
How to Improve Validity in Psychological Research
1️⃣ Use standardised procedures
2️⃣ Reduce investigator and participant bias
3️⃣ Randomly allocate participants
4️⃣ Conduct pilot studies to refine design
5️⃣ Replicate experiments to confirm findings
Each of these methods strengthens both internal and external validity — ensuring results are fair, accurate, and generalisable.
AQA Exam Tip
Explain one way in which a psychologist could assess the validity of a new test. (4 marks)
Model answer:
A psychologist could assess criterion validity by comparing the new test’s results with an existing valid test.
If both tests produce similar results, the new test is likely to have high validity.
Conclusion
Understanding the types of validity in psychology helps students evaluate research critically.
Each form of validity — from internal to ecological — strengthens the credibility of findings and ensures they reflect real behaviour.
Psychologists aim to strike a balance between control and realism, using techniques such as
randomisation,
standardisation, and
counterbalancing
to create fair, valid experiments.
📖 Further Reading:
- Reliability in Psychology: Learn how psychologists ensure consistent results across time, observers, and settings.
