Final answer:
Mary Ainsworth was a developmental psychologist known for her work in early emotional attachment and the development of attachment theory. She studied attachment between mothers and infants using the Strange Situation procedure and identified three types of parent-child attachments.
Step-by-step explanation:
Mary Dinsmore Salter Ainsworth was an American-Canadian developmental psychologist known for her work in early emotional attachment with the Strange Situation design, as well as her work in the development of attachment theory. Ainsworth's research involved studying attachment between mothers and their infants using the Strange Situation procedure, where the mother and infant are placed in a room together and their behaviors are observed. Based on her research, Ainsworth identified three types of parent-child attachments: secure, avoidant, and resistant. Her studies are considered cornerstones of modern-day attachment theory.