Final answer:
Developmental psychologists focus on infancy due to the critical developments in social, cognitive, and physical domains that occur during this period, including the formation of attachment bonds and the acquisition of object permanence.
Step-by-step explanation:
Developmental psychologists tend to look at changes that occur in infancy because this period is critical for social, cognitive, and physical development. During infancy, significant milestones are reached in various domains, such as motor skills, sensory abilities, and cognitive abilities, which include an understanding of concepts like object permanence. Additionally, infancy is essential for psychosocial development, including the formation of healthy attachments, which are considered major social milestones of infancy and a key interest area for these psychologists.
Researchers in this field seek to answer questions related to how infants form attachment bonds with their parents, the impact of neglect on these bonds, and the factors contributing to differences in children's attachments. Theories of development within this field address whether development is continuous or discontinuous, follows one course or many, and the relative influence of nature vs nurture. Knowledge obtained through these inquiries is vital for understanding human development across the lifespan.