When was the first self-control experiment using delayed gratification published?

Walter Mischel and colleagues published influential delayed gratification studies in the late 1960s and early 1970s. In these experiments, children were given a choice between a smaller immediate reward and a larger later reward. The research became famous as a way to study self-control, patience, and executive function. Later studies also showed that environment and trust influence how children make such choices, making the topic more complex than the original “willpower” story.