To maintain the integrity of a blinded study, placebos are designed to be indistinguishable from the active medication being tested. As shown in the image, this means they can come in various forms, such as different colored capsules or pills, to perfectly mimic the appearance of the experimental drug. This ensures that participants' expectations are not influenced by the appearance of the pill they receive.

Varying Forms of Placebos

A research team is conducting a study to determine the effectiveness of a new headache medication. One group of participants receives the new medication, while another group receives a pill that looks and tastes identical but contains no active ingredients. What is the primary scientific reason for giving the second group this inactive pill?

Consider the following statement:

Sometimes, researchers will administer a(n) ________ to participants in the control group to control for the effects that participant expectation might have on the experiment.

The correct term to complete this statement is a **placebo**.

Controlling for Participant Expectation in Experiments

The placebo effect refers to a positive response or improvement in an individual's condition resulting from the administration of an inert, simulated treatment. This effect is primarily driven by the individual's psychological expectation that they will get better, which can autonomously reduce stress, anxiety, and depression, subsequently altering perceptions and even improving physiological functions like the immune system.

Placebo Effect

Many traditional or folk remedies that appear to be effective are likely functioning as placebos rather than active medical interventions. For instance, practices such as consuming chicken soup to cure a cold or placing a bar of soap under bed sheets to prevent nighttime leg cramps lack active medicinal ingredients, but they may produce positive health outcomes due to the individual's expectation that they will improve.

Folk Remedies as Placebos

A placebo effect is a positive outcome resulting from a simulated treatment, driven largely by an individual's expectation that they will improve. Holding the expectation of recovery can autonomously lead to physiological and psychological benefits, such as reduced stress, lower anxiety and depression, and enhanced immune system functioning, even without an active intervention.

A placebo control condition is an experimental group where participants receive a simulated intervention that lacks the active ingredient of the actual treatment but appears identical to it. By providing both the treatment and control groups with the expectation of improvement, any additional progress observed in the treatment group can be confidently attributed to the active ingredients rather than placebo effects.

Placebo Control Condition

Which of the following best describes a placebo in the context of psychological research?

A placebo is a simulated treatment that lacks any active ingredient or specific element intended to make it effective. Despite lacking active components, placebos are designed to mimic the appearance or experience of actual treatments, such as an identical-looking sugar pill in a drug trial or an unstructured conversation with a therapist in psychotherapy research.

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University of Michigan - Ann Arbor

Often used in clinical trials, a double-blinded experiment is an experimental technique in which neither the investigators nor the subjects know who is receiving an intervention or not.  It is to prevent bias.  

Double-Blinded Experiment

In psychological research, a treatment is defined as any intervention intended to change people's behavior for the better. This broad concept encompasses medical treatments and psychotherapies for psychological disorders, as well as various interventions designed to reduce prejudice, promote conservation, or improve learning.

Treatment

Experimental control is the fundamental process by which researchers hold extraneous variables constant throughout a study. Because extraneous factors—such as individual participant differences or situational contexts—are likely to have an unintended effect on the dependent variable, they make it difficult to separate their impact from the true effect of the manipulated independent variable. By actively controlling these outside variables and preventing them from fluctuating across conditions, researchers can isolate the independent variable and confidently attribute any changes in the dependent variable to the experimental manipulation.

Experimental Control

In an experiment, conditions refer to the distinct levels or variations of the independent variable that the researcher systematically creates through manipulation. Researchers typically assign these conditions short, descriptive names to make them easier to discuss. For example, a study investigating the effects of expressive writing on health might create a 'traumatic condition' and a 'neutral condition'.

Experimental Condition

H. Russell Bernard (March 2, 2012)

*Social Research Methods: Qualitative and Quantitative Approaches, Edition 2* 

Social Research Methods: Qualitative and Quantitative Approaches, Edition 2

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

https://kpu.pressbooks.pub/psychmethods4e/

KPU Research Methods in Psychology - 4th American Edition

Placebo

A treatment condition is an experimental group in which participants actively receive the specific intervention or treatment being evaluated. To determine whether an intervention is effective, researchers compare the outcomes of participants in this condition against those assigned to a control condition.

Treatment Condition

In psychological research, how is a 'treatment' defined?

Random assignment is the primary method used to control extraneous variables across experimental conditions. It involves using a chance-based procedure to determine which participants are placed into which conditions. Strictly speaking, it requires that every participant has an equal probability of being placed in any condition and that each individual's assignment is completely independent of the others.

Random Assignment

What is the primary purpose of experimental control in a research study?

A between-subjects experiment is an experimental design approach wherein each participant is exposed to only a single level of the independent variable. This method differs fundamentally from within-subjects designs, as individuals are tested in just one specific condition rather than across all experimental variations.

Between-Subjects Experiment

It is important for researchers to distinguish between an independent variable and its conditions. A single independent variable represents the overarching factor being manipulated, while the conditions are the multiple different levels or variations created within that single variable.

Distinguishing Independent Variables from Conditions

A control condition is an experimental baseline group in which participants do not receive the active treatment or intervention being tested. Researchers compare the outcomes of this untreated group to those in the treatment condition to ascertain if the intervention successfully produced a positive change.

Control Condition

In Darley and Latané’s bystander experiment, the independent variable was the perceived number of witnesses, which researchers manipulated to create three distinct conditions: participants believed there were either one, two, or five other students present. To maintain experimental control, the researchers held extraneous variables constant by testing everyone in the exact same room and exposing them to the identical simulated emergency. They also randomly assigned participants to these conditions to ensure the groups were similar from the start, effectively controlling for extraneous participant variables.

Example of Conditions and Control in Darley and Latané's Experiment

A single factor two-level design is an experiment that involves a single independent variable manipulated to create exactly two distinct conditions. For example, a researcher might investigate the effects of expressive writing by manipulating the independent variable to form two groups: a traumatic experience condition and a neutral experience condition.

Single Factor Two-Level Design

In an experiment, researchers systematically create distinct levels or variations of a specific factor to study its effects. What is the term used for these distinct levels?

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