Test the placebo effect
This activity will take 45 minutes, is for ages 7 to 10 with supervision needed.
The 'placebo effect' means that sometimes you feel better when taking a medicine that doesn't actually do anything, just because you expected it to work.
Test out the placebo effect with some friends or family and see how it works.
- Lemonade
- Red and green food colouring
- Clear cups or glasses (two for each person taking part)
- Spoon
Step by step
- Pour some lemonade into each cup. You’ll need two cups for each person taking part.
- Add a tiny bit of red food colouring to one cup for each person and stir with a spoon. The lemonade in these cups should now be pink.
- Get everyone together. Explain that there are two different types of lemonade to try, one clear and one pink. Do not tell anyone that the two lemonades are the same!
- Explain that the challenge is to taste the two drinks and tell which one is sweeter. They could say what they think will happen first and then they can go ahead and taste each drink.
- Ask each person which drink they thought was sweeter, the clear one or the pink one.
- After everyone has given their answer, reveal that the drinks are actually the same! Did anyone guess this? Did most people think the pink lemonade was sweeter?
What happened?
We can expect red or pink foods to taste sweeter than other coloured food. This can be so powerful that we actually taste them as sweeter, even when they aren't.
This effect can cause a problem when testing new medicines.
Imagine that you have a cold and you’re helping to test a new drug to cure the cold. You're given the new medicine by a scientist.
What would you expect to happen next? You’d probably expect to get better. This expectation can be enough to make you feel better, so it would be difficult to tell whether the medicine really worked or not.
When testing new medicines, this is fixed by giving half of the volunteers the real medicine and the other half a 'placebo'.
A placebo is a medicine that looks and feels the same as the real thing, but doesn't have any medicine in it. For example, people testing new vaccines might give half the people the vaccine, and the other half an injection of salt water.
Volunteers won’t know which one they had. At the end of the trial, scientists compare the two groups. If the volunteers given the real medicine improved more than the volunteers given the placebo, this shows that the drug has really been effective. It means that it's not just people's expectations.