Harry Harlow changed our understanding in child development. Harlow's work showed the importance of developing safe, secure, and supportive emotional bonds with caregivers during early childhood. Experts believed that if you payed attention to your child, he/she would grow up to be spoiled. This theory was found to be wrong. After his experiment, shown by the video below, Harlow found out all the monkey needed was the comfort of its mother, and then it would try to intimidate the threat.