Dehumanisation is when one group of people, denies the humanity of another group of people, often comparing them to pests and diseases. The whole point of dehumanisation is to completely get rid of the guilt for the people looking to exterminate another group, as as the other group isn’t human, there is no reason for them to feel sympathy towards this other group.
Therefore leading them to think that it is okay to get rid of this ‘sub-human” group. Dehumanisation was mainly spread through large amounts of hate propaganda around a certain country. For example the radio channel “Radio Télévision Libre des Milles collines” repeatedly broadcasting anti-tutsi messages, such as “kill the cockroaches” or “if this disease is not treated immediately, it will destroy all Hutu”. As they were compared to cockroaches or a disease, it implies that they are unwanted, or even possibly damaging to the society. This was meant to invoke the superiority of one group over an other, examples of these are found in the Nazi party, or in the Rwandan Genocide, where the Hutu were exterminating the Tutsi, among many other genocides.