A team of researchers wants to know whether preschoolers bec…

A team of researchers wants to know whether preschoolers become “kinder” after a new classroom curriculum. Before starting, they decide to count how many times each child shares a toy, comforts a crying classmate, or helps clean up during a 30-minute observation period. What research step does this decision represent?

Jordan, age 45, notices he can no longer read the fine print…

Jordan, age 45, notices he can no longer read the fine print on a menu without holding it at arm’s length. This realization leads him to reflect on his own aging, which motivates him to start walking every morning before work. After a few months of walking, he notices he’s sleeping better and feels less irritable with his kids. This sequence of events best illustrates which principle of the Lifespan Perspective?