Final answer:
While behaviorists originally believed infants attached to mothers for satisfaction of hunger and thirst, Harlow's research with monkeys and Bowlby's attachment theory showed that comfort, security, and responsive caregiving are crucial for attachment.
Step-by-step explanation:
The theorist who suggested that infants become attached to their mothers because they satisfy basic desires for hunger and thirst was originally proposed by behaviorists before the contributions of Harry Harlow. However, Harlow's research in the 1950s challenged this notion. Harlow's experiments with rhesus monkeys demonstrated that the monkeys preferred a soft, cuddly cloth 'mother' that provided no nourishment over a wire mesh 'mother' that did dispense milk. This indicated that comfort and security play a critical role in the mother-infant bond, beyond just the satisfaction of basic physiological needs. Later, John Bowlby developed the concept of attachment theory, fundamentally changing our understanding of child development. Rather than attachment being based solely on the fulfillment of basic needs like hunger and thirst, Bowlby emphasized the importance of a secure base and responsive caregiving for a child's social and emotional development.