Abstract: Studying basic psychological needs in a unidimensional way supplements the general framework of need satisfaction research by exploring the uniqueness of each need satisfaction (i.e., autonomy, relatedness, or competence satisfaction). This article reviews the theoretical basis of the psychological mechanisms (the intrinsic motivation and the internalization of extrinsic motivation) and the research status quo of the need satisfaction successively from three unidimensional perspectives, i.e., the additive, synergistic and balanced perspectives. Notably, inspired by the three perspectives, the article provides insights for the “limited interchangeability” of each need satisfaction’s influence on individuals’ psychological functioning. Future studies may keep digging the need satisfactions from the three unidimensional perspectives, and explore the compensatory association among the three need satisfactions, the neurological basis of each need satisfaction, and the basic psychological need frustrations in a unidimensional way.

Key words: need satisfactions, Self-determination Theory, additive perspective, synergistic perspective, balanced perspective