Which of the following is a key attachment theorist?

John Bowlby is a key figure in attachment theory, which explores the bonds between children and their caregivers and how these relationships impact emotional development and later interactions in life. Bowlby posited that the attachment between a child and their primary caregiver is crucial for survival and well-being, leading to the idea that children have an innate tendency to seek proximity to their caregivers. This foundational work in attachment theory emphasizes the importance of a secure base, which supports emotional and social development throughout a person's life.

The other theorists mentioned, while influential in their respective fields, do not focus on attachment theory. Sigmund Freud contributed significantly to psychoanalysis and our understanding of childhood development through the lens of unconscious motivations. B.F. Skinner is best known for his work in behaviorism and the principles of operant conditioning, which examines how behavior is shaped by reinforcement and punishment rather than attachment. Lev Vygotsky focused on sociocultural theory, particularly how social interactions and cultural context shape cognitive development, rather than the emotional bonds highlighted by Bowlby.