Final answer:
Developmental psychologists focus on human growth and changes in physical, cognitive, and psychosocial domains across the lifespan. They do not typically study which drugs work best for heart disease or schizophrenia as that is more related to the medical field.
Step-by-step explanation:
As a developmentalist, or more formally, a developmental psychologist, you would study the lifelong process of human growth and change across three domains: physical development, cognitive development, and psychosocial development. Among the topics you mentioned, studying "what drugs work best for heart disease or schizophrenia" would be outside the scope of developmental psychology. This is more related to the field of medicine or pharmacology. Developmental psychologists focus on developmental milestones such as walking or puberty (physical development), changes in personality over time (psychosocial development), and what happens after retirement for divorce (lifespan development).