Placebos can relieve symptoms even when patients are told they are taking a placebo.
In several trials, people with conditions such as irritable bowel syndrome or chronic back pain improved after taking pills clearly labelled as placebos. They knew there was no active drug.
Why is this true?
The ritual of treatment, expectations and attention from a clinician all trigger real changes in the brain, including the release of the body's own painkillers. Placebos do not shrink tumours, but they reliably change how pain and nausea are experienced.
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Psychology facts describe the shortcuts your mind takes without asking permission. We misjudge randomness, remember interrupted tasks better than finished ones, and change our answers when a group disagrees with us. The entries here stick to findings that have held up under replication, avoid the pop-science versions that overstate them, and explain what the effect really predicts about everyday behaviour.