To understand when, how, and why people cheat, the ability to detect cheating in a laboratory setting is crucial. However, commonly used paradigms are confronted with a conflict between allowing participants to believe they can cheat unnoticed and allowing experimenters to detect cheating. This project aimed to develop and establish a new nonverbal task to resolve this conflict. Study 1 and Study 2 developed a new unsolvable paradigm called the Difference Spotting Task. In Study 1, participants were incentivized to indicate whether they found any difference between a pair of pictures without being asked to point the difference(s) out, so they could overreport their performance to earn extra money. Unbeknownst to them, the pairs of pictures from half of the items were identical so that the task could not be solved without cheating. This paradigm allowed experimenters to detect cheating for each unsolvable item. Study 3 examined the validity of the Difference Spotting Task and demonstrated it as a valid tool to assess cheating. The Difference Spotting Task is nonverbal and thus applicable to populations across age, educational level, and culture. In this unsolvable task, participants feel safe in cheating, and experimenters can detect cheating at the item level. The task holds the potential to gain acceptance by many researchers and facilitate the investigation of the underlying processes of cheating behavior.