Nobel Prize–winning psychologist Daniel Kahneman and his colleagues have shown that what we remember about the pleasurable quality of our past experiences is almost entirely determined by two things: how the experiences felt when they were at their peak (best or worst), and how they felt when they ended. This “peak-end” rule of Kahneman’s is what we use to summarize the experience, and then we rely on that summary later to remind ourselves of how the experience felt.