MCAT® ExamPsychological, Social, and Biological Foundations of BehaviorMedium
A research team is investigating the effects of a new stimulant medication on attention span. They administer the medication to one group of participants and a placebo to another group. Both groups then complete a standardized task designed to measure sustained attention. Which of the following best describes the role of the placebo in this study?
- AIt helps to control for the psychological effects of receiving a treatment.
- BIt serves as the independent variable, directly manipulated by the researchers.
- CIt acts as a confounding variable that the researchers aim to eliminate.
- DIt is the dependent variable, measuring the outcome of the intervention.
Show answer & explanationAnswer & explanation
Correct answer: A. It helps to control for the psychological effects of receiving a treatment.
A placebo is an inert substance or treatment given to a control group in an experiment. Its primary purpose is to account for the placebo effect, which is the psychological or physiological benefit experienced by a participant due to their belief in the treatment, rather than the treatment itself.
Why the other options are wrong
- B. The independent variable is the new stimulant medication, which is directly manipulated; the placebo is part of the control.
- C. A placebo is a control mechanism, not a confounding variable; confounding variables are uncontrolled factors that can influence results.
- D. The dependent variable is the attention span, which is measured; the placebo is part of the experimental design to isolate the independent variable's effect.
Placebo Effect
A psychological or physiological response to a 'fake' treatment (placebo) that is not due to any active ingredient, but rather to the participant's belief in the treatment or the expectation of benefit.
- Can produce real physiological changes.
- Controlled for in clinical trials using blind or double-blind designs.
- Highlights the power of expectation and belief in health outcomes.
Memory trick: Controls ensure experiments are clean, like a pristine lab scene.