Expectation Bias
Expectation Bias is when what you believe will happen changes what you actually see, feel, or do.
Two bowls of soup sit on a counter, both from the same pot. One bowl has a label that says "extra spicy" and the other has no label. People who see the spicy label say the soup tastes hotter, even though it is the same. What they read on the label changed what they felt on their tongue.
Explaining expectation bias by grade level
Give two groups the same drink in different colored cups. Tell one group it is grape and the other it is lime. Most people will say they taste grape or lime, even though both drinks are the same. What they were told changed what they tasted.
Projects that explore expectation bias
Expectation bias can alter physical performance, not just perception. Three groups of runners drink the same sweetened water but hear different claims about it. Runners told the drink boosts stamina run faster, and those told it will slow them down run slower.
What you believe will happen can change what you actually see, feel, or do. Adding red, orange, and purple food dye to identical drinks changes what people report tasting. The red drink is called strawberry and the purple one is called grape, even though every batch has the same lime juice.