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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 todemand characteristicsor theplacebo 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.
A Closer Look at Double-Blind Studies
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 arerandomly assignedto the control group. A control group is a subset of participants who are not exposed to any levels of theindependent variable. This group serves as a baseline to determine if exposure to the independent variable had any significant effects.
Those randomly assigned to theexperimental groupare given the treatment in question. Data collected from both groups are then compared to determine if the treatment had some impact on thedependent 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 ofpsychotherapyis the most effective, it would be impossible to keep participants in the dark about whether or not they actually received therapy.
Reasons to Use a Double-Blind Study
So why would researchers opt for such a procedure? There are a couple of important reasons.
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
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.
2 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health.FAQs About Clinical Studies.Misra S.Randomized double blind placebo control studies, the “Gold Standard” in intervention based studies.Indian J Sex Transm Dis AIDS. 2012;33(2):131-4. doi:10.4103/2589-0557.102130Additional ReadingGoodwin, CJ.Research In Psychology: Methods and Design. New York: John Wiley & Sons; 2010.Kalat, JW.Introduction to Psychology. Boston, MA: Cengage Learning; 2017.
2 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health.FAQs About Clinical Studies.Misra S.Randomized double blind placebo control studies, the “Gold Standard” in intervention based studies.Indian J Sex Transm Dis AIDS. 2012;33(2):131-4. doi:10.4103/2589-0557.102130Additional ReadingGoodwin, CJ.Research In Psychology: Methods and Design. New York: John Wiley & Sons; 2010.Kalat, JW.Introduction to Psychology. Boston, MA: Cengage Learning; 2017.
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Institutes of Health.FAQs About Clinical Studies.Misra S.Randomized double blind placebo control studies, the “Gold Standard” in intervention based studies.Indian J Sex Transm Dis AIDS. 2012;33(2):131-4. doi:10.4103/2589-0557.102130
National Institutes of Health.FAQs About Clinical Studies.
Misra S.Randomized double blind placebo control studies, the “Gold Standard” in intervention based studies.Indian J Sex Transm Dis AIDS. 2012;33(2):131-4. doi:10.4103/2589-0557.102130
Goodwin, CJ.Research In Psychology: Methods and Design. New York: John Wiley & Sons; 2010.Kalat, JW.Introduction to Psychology. Boston, MA: Cengage Learning; 2017.
Goodwin, CJ.Research In Psychology: Methods and Design. New York: John Wiley & Sons; 2010.
Kalat, JW.Introduction to Psychology. Boston, MA: Cengage Learning; 2017.
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