Final answer:
Humanistic psychology, as proposed by theorists like Abraham Maslow and Carl Rogers, emphasizes intrinsic motivation and the individual's innate desire to realize their full potential.
Step-by-step explanation:
The theoretical perspective that believes development is based on intrinsic sources of motivation is humanistic psychology. Humanistic psychologists like Abraham Maslow and Carl Rogers posited that people are motivated by an innate drive to achieve their fullest potential, striving toward self-actualization. This intrinsic motivation stems from an individual’s internal desires for growth and self-fulfillment as opposed to external incentives or rewards. Maslow's hierarchy of needs illustrates this concept, differentiating between deficit needs (which address absence) and being needs (which facilitate growth).