What primary variable did Harry Harlow’s experiment explore in terms of infant development?

Harry Harlow's experiment primarily explored the importance of comfort and security in infant development. Harlow conducted a series of studies with rhesus monkeys, where he offered the infants the choice between two surrogate mothers: one made of wire that provided food and another covered in soft cloth that offered no food but provided warmth and comfort. The results showed that the infant monkeys overwhelmingly preferred the cloth mother, spending significantly more time with it, despite the absence of food.

This preference illustrated the crucial role of emotional attachment and the need for security that infants have, which Harlow argued is foundational for healthy emotional development. The findings emphasized that the bonds formed through comfort and security are vital for a child's overall psychological well-being, supporting the idea that attachment goes beyond mere nourishment and delves into the emotional connections that influence social and emotional development.

In contrast, while feeding practices, social learning, and cognitive development are important aspects of child development, Harlow's primary focus was to reveal how comfort and a secure base affect attachment and, consequently, development and behavior later in life.