Final answer:
Harry Harlow's studies showed that baby monkeys preferred a soft terrycloth "mother" over a wire-mesh "mother" with a bottle, emphasizing the importance of comfort and security in the development of attachment.
Step-by-step explanation:
Harry Harlow's landmark experiments investigating attachment theory used baby monkeys and various surrogate mothers. According to his findings, baby monkeys preferred a soft terrycloth "mother" to a wire-mesh "mother" that held a bottle. This preference highlighted that the monkeys valued the comfort and security provided by the cloth "mother" over the nourishment from the wire-mesh "mother." Despite needing to feed, the monkeys would spend their time with the terrycloth mother unless feeding was necessary, deeply challenging the then-prevailing belief that attachment derives primarily from the fulfillment of basic needs like nourishment. Harlow concluded that bonding extends beyond food and involves the critical components of comfort and security for healthy psychosocial development.