Aresearcher is interested in how the aging process changes parent-child relationships. the researcher is most likely a psychologist.

Development psychologist

Explanation:

Development psychologists work in the area of human development and growth that occur throughout the lifetime. The development of psychology does not include only physical development but it also includes the cognitive, intellectual, personality and emotional and social growth.

The cognitive psychologist helps us to understand how people grow and how people change throughout the life span. The developmental psychologist helps people to know how the environmental, social factor influences the growth of the person. The developmental psychologist work in different area such as research field, clinical settings, universities, schools, community, etc.