Which two developmental psychologists believed that there is a substantial change in personality over time, and that change follows a set, predictable pattern?

Erikson & Levinson

Explanation:

Erikson & Levinson expressed similar ideas about personality development. Both studies the formal examination of a person's life into adulthood. However, the theory of Erikson emphasizes more on the notion that early development determines and influences an individual's personality and identity later in life. Though both agreed that personality evolves throughout life and found predictable patterns of it.