Harry F. Harlow
Harry Harlow's Research into Human Behavior was Ground-Breaking
However, all the monkeys suffered extreme effects, and were either unable to find a mate, or served as inadequate or abusive parents. This led Harlow to the conclusion that mothers are supposed to bond with their children as well as giving them nourishment, which was a fundamental change to the way mother-child relations were viewed.
Harlow witnessed the monkeys raised by dummy mothers struggle to find a mate in the correct way. If the monkey did have a child, they were either emotionally neutral to it ( doesn't hate, doesn't love) or were very abusive. The abusive mothers would end up being so abusive that many of the babies ended up dying.