Most people are familiar with placebos. It’s the treatment substitute in an experiment that participants think is the real treatment. Fewer people are familiar with the expectation effect. It’s the psychological phenomenon we experience when a placebo changes how we perceive something. For example, people who thought they were in the presence of an allergen have had allergic reactions as if it was really there. Their expectation literally caused the allergic reaction with no allergen present.

The video below shows that you can’t even stop the expectation effect when you know it’s there. Your brain fills in the colors it expects to see. It’s interesting how much our brains have adapted to save energy.

What things in your life can you think of being influenced by your expectations (like a placebo)?