Which animal did Harlow test his attachment theory on?

Harlow tested his attachment theory primarily on baby monkeys, specifically rhesus monkeys. His experiments were designed to investigate the nature of attachment and the effects of maternal separation on emotional and social development. He presented the infants with two surrogate mothers: one made of wire that provided food and another made of soft cloth that offered comfort.

The key finding from Harlow's research was that the baby monkeys preferred to spend time with the cloth mother, demonstrating that the need for comfort and emotional security can be more significant than the basic need for nutrition. This highlighted the importance of caregiving and emotional bonds in early development, shaping our understanding of attachment not only in primates but also influencing theories in human development.

In contrast, the other choices do not reflect Harlow's experiments, as his pioneering work was concentrated on primate behaviors rather than elephants, dogs, or cats, which were not part of his attachment studies. By focusing on baby monkeys, Harlow was able to provide valuable insights into attachment theory that have been foundational in both psychology and child development.