Final answer:
Harry Harlow's research indicated that contact comfort is more crucial than food in the formation of attachment among rhesus monkeys. His findings highlighted the fundamental necessity of social comfort and the tactile bond in the early stages of development, influencing the theory of attachment greatly.
Step-by-step explanation:
Harry Harlow's research with macaque monkeys raised with surrogate mothers led him to conclude that b) Contact comfort is more important than food in attachment. Through his studies involving rhesus monkeys and surrogate mothers, Harlow demonstrated that the monkeys preferred a soft terrycloth 'mother' that provided no sustenance over a wire mother that provided food, emphasizing the importance of social comfort and contact comfort over mere nutritional fulfillment.
Harlow's experiments from 1957 to 1963 revealed that while nourishment is necessary for survival, the emotional and social needs such as comfort, security, and loving touch from a caregiver play a vital role in healthy psychological development. The monkeys, even in the absence of food, sought the comfort of the terrycloth mother, which simulated the tactile comfort a real mother would provide. Later studies by Harlow showed that deprivation of social contact led to severe developmental and emotional problems, underscoring that the quality of early caregiver interactions is critical for normal social and emotional development.