What preference did monkeys show in Harlow's attachment experiment?

In Harlow's attachment experiment, monkeys demonstrated a clear preference for the soft mother, which represented comfort and security, over the wire mother that provided food. This finding was significant because it illustrated the importance of emotional and physical comfort in the formation of attachment, contrasting with behaviors based solely on the provision of basic needs, such as food.

The experiment involved two surrogate mothers: one made of wire that provided nourishment and another made of soft cloth that offered no food but offered a comforting presence. Monkeys consistently preferred to spend their time with the soft mother, returning only to the wire mother for feeding when necessary. This behavior underscored the notion that attachment is rooted more in emotional bonding and comfort rather than merely meeting physiological needs, which has profound implications in understanding attachment behaviors, not only in primates but also in human development.