At what age does hard work add a shine to lousy prizes?

Putting in a lot of effort to earn a reward can make unappealing prizes more attractive to kindergartners, but not to preschoolers, according to new research. The findings revealed that when six-year-olds worked hard to earn stickers that they ultimately didn't like, they were loath to give them up, whereas four-year-olds were comparatively eager to give the unappealing stickers away.