Final answer:
Harry Harlow studied rhesus monkeys in experiments that contributed to our understanding of social development, demonstrating the importance of emotional bonds and social comfort over mere sustenance in the attachment process.
Step-by-step explanation:
Harry Harlow studied b. Monkeys to learn more about the importance of caregivers in social development. Specifically, he conducted experiments on rhesus monkeys to understand the effects of social isolation and mother-infant bonding on psychological development. Harlow and his colleagues found that the monkeys preferred physical and emotional comfort over sustenance, indicating that social comfort is more important than food in the social development of young primates. These findings contributed significant insights into the attachment theory and underscored the importance of caregiving beyond the physiological needs of offspring.
In his experiments using surrogate mothers made of wire mesh and soft terrycloth, Harlow demonstrated that rhesus monkeys systematically chose the terrycloth mother for comfort, despite her inability to provide food. These studies highlighted that emotional and social needs are vital for healthy psychological development and played a pivotal role in how we understand infant-caregiver attachment.