What is the name for a study in which both the researchers and the participants are blind to group assignments?

Q: In what study are both the researcher and the participants unaware of group assignments?

A double-blind study withholds each subjects group assignment from both the participant and the researcher performing the experiment. If participants know which group they are assigned to, there is a risk that they might change their behavior in a way that would influence the results.

Inhaltsverzeichnis Show

Section 6: Blinding
Case Example for Blinding
Section 6: Discussion Questions
A Closer Look at Double-Blind Studies
Reasons to Use a Double-Blind Study
A Word From Verywell
When both participants and the researchers are unaware of the group assignment what kind of study is this an example of?
In what study are both the researcher and the participants unaware of group assignments?
What is a blind study in research?
What is a double

Module 3:
Objectives
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Section 1
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Section 2
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Section 3
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Section 4
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Section 5
Section 6
Quiz

Section 6: Blinding

Blinding is a technique used to decrease bias on the part of the researcher or the participant. In some studies, the participant is not told to which group they have been assigned. This is called single blinding. There is another level of blinding called double blinding where neither the researcher nor the participant know which group the participant is in until this information is revealed at the end of the study. Blinding can reduce the temptation to ignore random assignment procedures and can reduce any expectations about the potential effectiveness of the treatment or program since group assignment remains unknown by the participant, the researcher or both the participant and researcher. The results are more likely to provide information about the true effect of the treatment or program being tested when blinding is used.

Definition: Blinding is a technique used to decrease bias on the part of the researcher or the participant where the participant, or both the researcher and the participant are not told to which group they have been assigned.

Case Example for Blinding

In a study investigating the effects of a new anti-itch cream, participants with minor skin rashes were randomly divided into one of three groups. In the first group, participants received a new anti-itch cream that contained 3% hydrocortisone. In the second group, the participants received the standard cream available over-the-counter which contains 1% hydrocortisone. The third and final group members received a cream that contained 0% hydrocortisone. The participants did not know to which group they were assigned. Participants used the cream for three days to relieve itching symptoms caused by the rash. After three days, each participant’s rash was examined to determine if itching symptoms subsided. If this was not the case, the participant was provided with the standard treatment, which is known to relieve itching.

Section 6: Discussion Questions

Why are participants not told (blind to) their group assignment?

Is this a single or double blind study?

Do you think knowledge of group assignment (no blinding) would affect the results? Why or why not?

Do you think that the researcher’s knowledge of group assignment would affect the results? Why or why not?

A double-blind study is one in which neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results. Double-blind studies are particularly useful for preventing bias due to demand characteristics or the placebo effect.

For example, let's imagine that researchers are investigating the effects of a new drug. In a double-blind study, the researchers who interact with the participants would not know who was receiving the actual drug and who was receiving a placebo.

Illustration by Emily Roberts, Verywell

Let’s take a closer look at what we mean by a double-blind study and how this type of procedure works. As mentioned previously, double-blind indicates that the participants and the experimenters are unaware of who is receiving the real treatment. What exactly do we mean by ‘treatment'? In a psychology experiment, the treatment is the level of the independent variable that the experimenters are manipulating.

This can be contrasted with a single-blind study in which the experimenters are aware of which participants are receiving the treatment while the participants remain unaware.

In such studies, researchers may use what is known as a placebo. A placebo is an inert substance, such as a sugar pill, that has no effect on the individual taking it. The placebo pill is given to participants who are randomly assigned to the control group. A control group is a subset of participants who are not exposed to any levels of the independent variable. This group serves as a baseline to determine if exposure to the independent variable had any significant effects.

Those randomly assigned to the experimental group are given the treatment in question. Data collected from both groups are then compared to determine if the treatment had some impact on the dependent variable.

All participants in the study will take a pill, but only some of them will receive the real drug under investigation. The rest of the subjects will receive an inactive placebo. With a double-blind study, the participants and the experimenters have no idea who is receiving the real drug and who is receiving the sugar pill.

Double-blind experiments are simply not possible in some scenarios. For example, in an experiment looking at which type of psychotherapy is the most effective, it would be impossible to keep participants in the dark about whether or not they actually received therapy.

So why would researchers opt for such a procedure? There are a couple of important reasons.

First, since the participants do not know which group they are in, their beliefs about the treatment are less likely to influence the outcome.
Second, since researchers are unaware of which subjects are receiving the real treatment, they are less likely to accidentally reveal subtle clues that might influence the outcome of the research.

The double-blind procedure helps minimize the possible effects of experimenter bias. Such biases often involve the researchers unknowingly influencing the results during the administration or data collection stages of the experiment. Researchers sometimes have subjective feelings and biases that might have an influence on how the subjects respond or how the data is collected.

In one research article, randomized double-blind placebo studies were identified as the "gold standard" when it comes to intervention-based studies. One of the reasons for this is the fact that random assignment reduces the influence of confounding variables.

Example

Imagine that researchers want to determine if consuming energy bars before a demanding athletic event leads to an improvement in performance. The researchers might begin by forming a pool of participants that are fairly equivalent regarding athletic ability. Some participants are randomly assigned to a control group while others are randomly assigned to the experimental group.

Participants are then be asked to eat an energy bar. All of the bars are packaged the same, but some are sports bars while others are simply bar-shaped brownies. The real energy bars contain high levels of protein and vitamins, while the placebo bars do not.

Because this is a double-blind study, neither the participants nor the experimenters know who is consuming the real energy bars and who is consuming the placebo bars.

The participants then complete a predetermined athletic task, and researchers collect data performance. Once all the data has been obtained, researchers can then compare the results of each group and determine if the independent variable had any impact on the dependent variable.

A Word From Verywell

A double-blind study can be a useful research tool in psychology and other scientific areas. By keeping both the experimenters and the participants blind, bias is less likely to influence the results of the experiment.

A double-blind experiment can be set up when the lead experimenter sets up the study but then has a colleague (such as a graduate student) collect the data from participants. The type of study that researchers decide to use, however, may depend upon a variety of factors, including characteristics of the situation, the participants, and the nature of the hypothesis under examination.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Additional Reading

Goodwin, CJ. Research In Psychology: Methods and Design. New York: John Wiley & Sons; 2010.
Kalat, JW. Introduction to Psychology. Boston, MA: Cengage Learning; 2017.

By Kendra Cherry
Kendra Cherry, MS, is an author and educational consultant focused on helping students learn about psychology.

Thanks for your feedback!

When both participants and the researchers are unaware of the group assignment what kind of study is this an example of?

In a double-blind study , both the researchers and the participants are blind to group assignments. Why would a researcher want to run a study where no one knows who is in which group? Because by doing so, we can control for both experimenter and participant expectations.

In what study are both the researcher and the participants unaware of group assignments?

A double-blind study withholds each subject's group assignment from both the participant and the researcher performing the experiment. If participants know which group they are assigned to, there is a risk that they might change their behavior in a way that would influence the results.

Listen to pronunciation. (BLINE-ded STUH-dee) A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given. The opposite of a blinded study is an open label study.

What is a double

Listen to pronunciation. (DUH-bul-blind STUH-dee) A type of clinical trial in which neither the participants nor the researcher knows which treatment or intervention participants are receiving until the clinical trial is over.