AQA Syllabus focus:
'Demand characteristics and investigator effects; ethics, the British Psychological Society’s code, ethical issues and dealing with ethical issues.'
This subtopic examines how participant expectations, researcher influence, and ethical rules can shape psychological investigations. Understanding them helps you evaluate research quality and explain how psychologists protect participants and produce trustworthy findings.
Demand characteristics and investigator effects
Demand characteristics
Demand characteristics are a major source of bias in psychological research because participants may try to work out what the study is about and then adjust their behavior.
Demand characteristics: Cues in a research situation that allow participants to guess the aim of the study and change their behavior.
These cues can come from the setting, the instructions, the tasks, or the behavior of the researcher.
This diagram summarizes demand characteristics as cues in the research context that signal the study’s aims to participants. It also categorizes where those cues typically originate (e.g., study setting/procedure and the researcher’s interactions), helping you link “participant guessing” to specific, controllable features of a study design. Source
Demand characteristics are especially likely in research where the purpose seems obvious. Participants may try to help the researcher by acting in a way they think is expected, or they may try to undermine the study by acting unusually. In both cases, the behavior recorded may not reflect genuine responses.
This matters because results may be less valid. If participants respond to the perceived aim rather than the actual situation, the findings do not accurately show what the researcher intended to measure. Demand characteristics can therefore reduce confidence in the conclusions drawn from a study.
Psychologists try to reduce demand characteristics by:
giving standardized instructions that do not reveal the hypothesis
avoiding obvious clues about the aim of the study
using tasks that seem unrelated to the real purpose
making the research setting feel as natural and neutral as possible
asking participants afterward what they thought the study was about, to check whether the aim was guessed
Investigator effects
Participant behavior is not the only source of bias. The researcher can also influence the outcome, sometimes without meaning to.
Investigator effects: Any influence of the researcher’s behavior, expectations, or presence on participants or on the recording of data.
Investigator effects happen when the researcher’s tone of voice, facial expression, body language, or expectations affect participants. For example, a researcher may accidentally give hints about the “right” response, ask questions in a leading way, or record behavior differently because they expect a certain result.
This is a problem because findings may reflect the researcher’s influence rather than the participants’ true behavior. Investigator effects can also make a study harder to repeat consistently, especially if different researchers behave differently.
Ways to reduce investigator effects include:
This graphic contrasts single-blind and double-blind designs, showing who is kept unaware of group assignment in each case. It illustrates how blinding reduces expectancy-based influence from both participants and researchers, which is a key practical control for investigator effects. Source
using standardized procedures so every participant is treated the same way
training researchers to follow the same instructions and avoid leading behavior
using clear scoring criteria so judgments are less subjective
recording responses in an objective way where possible, such as using fixed-answer formats or automated measures
keeping personal expectations separate from data collection and scoring
Ethics and the BPS code
Ethics refers to the moral standards that guide psychological research. The British Psychological Society (BPS) provides a code of conduct and guidance to help psychologists carry out research responsibly. The aim is to protect participants, maintain professional standards, and preserve public trust in psychology.
The BPS code does not simply tell researchers to avoid obvious harm. It also encourages psychologists to think carefully about dignity, respect, privacy, and responsibility. A study should have clear value, but that value does not remove the need to protect participants.
Main ethical issues
Some ethical issues appear repeatedly in psychological research.
Informed consent means participants should agree to take part with enough knowledge about what the study involves. Consent is only meaningful if it is given freely and not under pressure.
Deception happens when participants are misled about the true purpose or nature of the study. This may sometimes be used to prevent demand characteristics, but it creates ethical concerns because participants cannot fully understand what they are agreeing to.
Protection from harm means participants should not be exposed to physical or psychological risk greater than they would normally face in everyday life. Harm can include stress, embarrassment, fear, lowered self-esteem, or lasting emotional upset.
Right to withdraw means participants should be able to leave the study at any point. They should not feel trapped, and they should not be pressured to continue once discomfort begins.
Confidentiality and privacy mean personal information should be protected. Participants should not be identifiable in published findings unless they have clearly agreed to this.
Dealing with ethical issues
Psychologists are expected not only to identify ethical problems but also to deal with them appropriately.
Before the study begins, researchers should think through possible risks and change the design if needed. Consent procedures should be clear, and participants should know that participation is voluntary. If a task may be upsetting, this should be considered in advance rather than dealt with only afterward.
If deception is used, it should be kept to a minimum and only used when necessary. The researcher must be able to justify why the study could not be done in a less misleading way. Even then, deception should never expose participants to harm they have not agreed to.
During the study, researchers should monitor participants carefully. If someone becomes distressed, the procedure should be paused or stopped. Participant welfare always takes priority over completing the investigation.
After the study, a debrief should take place. This means explaining the true aim, revealing any deception, answering questions, and checking that the participant leaves in an appropriate emotional state. A good debrief can reduce possible harm and help restore informed understanding.
To protect confidentiality, psychologists should anonymize data, store information securely, and report findings in a way that does not reveal identity. Researchers must keep any ethical cost as low as possible and be able to justify the study’s value.
Practice Questions
Describe what is meant by demand characteristics. (2 marks)
1 mark for identifying that there are cues in the research situation.
1 mark for stating that these cues lead participants to guess the aim and change their behavior.
Explain the difference between demand characteristics and investigator effects. Discuss one way of reducing each in psychological research. (6 marks)
1 mark: Demand characteristics are cues that reveal the aim of the study to participants.
1 mark: Participants change their behavior because of these cues.
1 mark: Investigator effects occur when the researcher influences participants or the recording of data.
1 mark: This influence may come from expectations, tone, body language, or biased observation.
1 mark: One appropriate way to reduce demand characteristics, such as neutral instructions, fewer clues, or using tasks that disguise the true aim.
1 mark: One appropriate way to reduce investigator effects, such as standardized procedures, researcher training, automation, or clear scoring rules.
FAQ
A single-blind procedure means the participant does not know the true aim or condition they are in, but the researcher does.
A double-blind procedure means neither the participant nor the person collecting the data knows the key condition information during the study.
Double-blind procedures are usually better for reducing both participant bias and researcher bias, but they are not always practical in every psychology study.
Presumptive consent means asking a similar group of people whether they think a proposed study would be acceptable.
It may be used when full informed consent would damage the study, especially in research involving some level of deception.
It does not replace the need for careful ethical judgment. Researchers still need to minimize harm, justify the design, and provide a full debrief afterward.
They may have less ability to understand the study fully, assess risk, or resist pressure from adults or authority figures.
Extra protection can include:
obtaining consent from a parent, guardian, or legal representative
gaining the participant’s own agreement where possible
using age-appropriate explanations
stopping the study immediately if distress appears
The ethical standard is higher because the risk of misunderstanding or exploitation is greater.
Online studies can make privacy, consent, and debriefing more difficult.
For example:
participants may not read consent information carefully
researchers may find it harder to check age or vulnerability
data security becomes especially important
participants may close the study early and miss the debrief
Researchers should use clear digital consent forms, secure data systems, and make debrief information easy to access even if the participant exits early.
In many cases, yes. This is often treated as an extension of the right to withdraw, especially if the data can still be identified and separated.
However, removal may be harder once data have been fully anonymized or combined into a final dataset.
Good practice is to tell participants:
whether withdrawal of data is possible
how long they have to request it
who to contact
Clear information at the start helps avoid confusion later.
