Fredrick Douglass Big Question

Dehumanization is a really important topic for me because, it's such a big part of slavery. A lot of slaves didn't have much feeling in them during slavery because of the violence and ignorance that was brought to them.Why did slave owners think that dehumanizing was the best way to treat their slaves? I will be using information from his Narrative and see how he was treated and how he keep the strength to not let them get to him. I will pay close attention to what his emotions were during the time he was a slave and also what his slave owner's emotions were at the time.What were the slave owners emotions towards the slave and Fredrick Douglass?