Final answer:
Arnold Gesell and Granville Stanley Hall developed the Maturation approach, focusing on the biological and genetic aspects of child development and establishing norms for developmental milestones through studies with large groups of children.
Step-by-step explanation:
Arnold Gesell and his colleague, Granville Stanley Hall, are known for developing the Maturation approach to child development. This approach, which falls under the normative approach to development, emphasizes the role of biological development and genetic factors in a child's growth. Gesell and Hall conducted studies with large groups of children to establish norms for various developmental milestones and to underscore the intrinsic timeline of a child's maturation process, independent of environmental factors. Gesell's work provided general guidelines to compare children with their same-age peers in terms of reaching key developmental markers. This research was foundational in the field of developmental psychology and provided key insights into the physical, cognitive, and psychosocial development of children.