Final answer:
Harry Harlow concluded that social comfort and security are more important than nourishment in the mother-child bond, based on his studies with surrogate mother experiments in rhesus monkeys.
Step-by-step explanation:
Harry Harlow's research with macaque monkeys raised with surrogate mothers led him to conclude that social comfort is more important than food. His experiments from the 1950s involving baby rhesus monkeys and two types of surrogate mothers—one made of wire mesh capable of dispensing milk, and another made from soft cloth but with no provision for nourishment—revealed that the monkeys favored the cloth surrogate, emphasizing the importance of feelings of comfort and security for healthy psychosocial development. Harlow's studies asserted the critical role of maternal-infant bonding based on these components, contradicting previous beliefs held by the scientific and medical communities that the attachment was primarily due to nourishment provided by the caregiver. This insight has had profound implications for the understanding of human and primate development. These experiments, however, are today considered unethical.