Indeed, depending on the socioeconomic status of a child, the perceived value of a sticker might change. The experimenters made sure that the stickers represented an asset with same scarcity in both higher and lower SES schools. In other words, stickers were equally commonly given to students in both schools. Furthermore, this stickers were brought from another country therefore, they would be equally rare for all children. With these two conditions, the experimenters tried to control for the perceived value of the stickers.