Below is a claim: Children will choose an apple over cookies if you just put you just put a sticker of a popular character on it . I do...

Below is a claim:

"Children will choose an apple over cookies if you just put you just put a sticker of a popular character on it" . I do not feel that this finding is believable. This is because it seems like the claim is trying to appeal to people by making them think that we have control over children's preferences. This also appeals to the new trend of eating healthy and being healthy. 

My question is, please explain how one could go about testing the claim scientifically?