Demand Characteristics in Psychology: Definition, Examples & How to Control Them

by Yum Yum Mama Team October 29, 2025

In psychological research, demand characteristics are subtle cues or signals that make participants guess the purpose of a study. Once they think they know what’s being investigated, they may change their behaviour — consciously or unconsciously — which threatens the validity of the results.

Understanding demand characteristics and learning how to control them is essential for designing fair, unbiased experiments. Along with standardisation, randomisation, and counterbalancing, managing demand characteristics is a key part of maintaining scientific credibility in psychological research.

What Are Demand Characteristics in Psychology?

Demand characteristics refer to any clues in an experimental situation that suggest to participants what behaviour is expected of them.

When participants pick up on these cues, they might:

Try to behave in a way that supports the hypothesis (helpful participant).
Deliberately behave opposite to the hypothesis (screw-you effect).
Behave unnaturally to appear in a positive light (social desirability bias).

Example of Demand Characteristics

Imagine a psychologist testing whether people who meditate daily have better focus.
If participants realise the study is about meditation and concentration, they might put extra effort into focusing — not because of meditation, but because they want to “do well.”

That change in behaviour is caused by demand characteristics, not the independent variable.

Types of Demand Characteristics

There are several ways participants may respond to perceived expectations:

1️⃣ The Good Participant Effect

They try to confirm what they think the researcher wants.

Example: Guessing the aim of a memory test and intentionally performing well.

2️⃣ The Screw-You Effect

They deliberately do the opposite of what they think the researcher expects.

Example: Underperforming on purpose to disrupt the results.

3️⃣ The Apprehensive Participant Effect

They behave unnaturally because they want to appear intelligent, moral, or competent.

Example: Over-reporting healthy habits or hiding socially undesirable behaviour.

⚠️ Why Are Demand Characteristics a Problem?

Demand characteristics reduce internal validity because the experiment no longer measures the effect of the independent variable alone. Instead, results reflect participants’ reactions to the situation.

🔹 Key problems:

Reduces validity: Behaviour may not represent true responses.
Introduces bias: Participants try to “help” or “hinder” results.
Hurts reliability: Makes replication inconsistent.

👉 For other factors that threaten validity, see Extraneous and Confounding Variables in Psychology.

🔧 How to Control Demand Characteristics

Psychologists use several control techniques to reduce the influence of demand characteristics.

Clear Operationalisation reduces ambiguity in instructions, helping to minimise demand characteristics and participant guesswork.

1️⃣ Single-Blind Design

Participants don’t know the true aim of the study.

Example: They’re told it’s about “problem-solving,” not “stress levels.”

2️⃣ Double-Blind Design

Neither the participant nor the experimenter knows which condition the participant is in.

Example: Used in drug trials to prevent both researcher and participant bias.

3️⃣ Deception (Ethical Use)

Researchers sometimes conceal the full aim of the study until after data collection — followed by a proper debrief.

4️⃣ Standardisation

Keeping procedures and instructions identical reduces variation in cues.

Learn more: Standardisation in Psychology

5️⃣ Randomisation

Using chance to allocate participants or order conditions helps avoid patterns that might reveal the hypothesis.

Learn more: Randomisation in Psychology

Minimising participant awareness helps protect a study’s internal validity, ensuring that behaviour changes are due to the experiment itself.

Controlling participant awareness increases both internal validity and reliability in psychology by producing more consistent responses.

Even when researchers successfully reduce participant bias, their studies may still lack ecological validity if the tasks or environments don’t reflect real-life behaviour.

Demand Characteristics vs Investigator Effects

Although both can bias results, they stem from different sources:

Feature	Demand Characteristics	Investigator Effects
Source	Participants guess the study’s purpose	Researcher’s behaviour influences participants
Example	Participant tries to behave as expected	Researcher smiles when a certain answer is given
Control	Single/double-blind design	Training, automation, or double-blind setup

👉 Investigator Effects in Psychology — this article will explore how researchers themselves can unintentionally affect results.

📘 Demand Characteristics in A-Level Psychology (AQA)

In the AQA Research Methods unit, students must:

Define demand characteristics.
Explain how they threaten validity.
Suggest ways to control them.

Example Exam Question

Explain what is meant by demand characteristics and how they could affect the results of a study. (4 marks)

Model answer:

Demand characteristics are cues in an experiment that make participants aware of its purpose. They may change their behaviour to fit or oppose expectations, reducing the study’s validity. Researchers can use single- or double-blind procedures to control this.

FAQs

1️⃣ What are demand characteristics in psychology?
They are cues that make participants aware of the study’s purpose, causing them to change their behaviour.

2️⃣ How do demand characteristics affect validity?
They reduce internal validity because behaviour no longer reflects the natural effect of the independent variable.

3️⃣ How can demand characteristics be controlled?
Through single-blind and double-blind designs, deception, randomisation, and standardisation.

4️⃣ Are demand characteristics ethical?
They are not unethical themselves, but controlling them sometimes involves deception — which must be handled ethically through debriefing.

Conclusion

Demand characteristics are a major threat to the validity of psychological research. By making participants aware of what’s expected, they can unintentionally distort results.

Using single- and double-blind procedures, standardisation, and randomisation helps researchers control these effects and produce fair, unbiased data.

📖 Next read:

Types of Validity Psych – Discover how validity ensures fair, accurate results across all psychological research.

Extraneous and Confounding Variables in Psychology

Counterbalancing in Psychology

Standardisation in Psychology

Explore how psychologists test consistency over time and across observers in our article on Reliability in Psychology.