Motivation Science, Vol 12(1), Mar 2026, 16-18; doi:10.1037/mot0000417
In this commentary in honor of Julius Kuhl, I reflect on decades of dialogue and collaborations between his works in personality systems interactions theory and research within self-determination theory. Both frameworks are rooted in an organismic metapsychology, emphasizing human capacities for integration and self-regulation. I highlight several points of convergence: the role of autonomy support in facilitating adaptive functioning, especially among state-oriented individuals; the shared recognition that well-internalized goals yield vitality and more effortless willpower; and parallel findings in neuroscience linking self-access and awareness to more autonomous motivation. Although differences and critiques have occasionally arisen, personality systems interactions and self-determination theory remain “sibling theories,” offering largely complementary insights into motivation and personality. This essay reflects on their intersections and underscores the value of open and thoughtful dialogues between theories in motivational science. (PsycInfo Database Record (c) 2026 APA, all rights reserved)