From deportation from Sighet to murder at Birkenau, deception was often used to confuse the prisoners. How does deception dehumanize?
Deception was a key instrument for the Nazis to confuse the general population, not just Jews, about their real agenda. In a way, the Germans were even deceiving themselves with their exaggerated sense of nationalism and their propaganda machinery—much like what is going on with North Korea in this day and age.
When it came to concentration camps the most notable deception is found in the way that the Auschwitz camp "greeted" the prisoners:
“Arbeit macht frei” or “Work makes you free.”
In reality, there was no freedom to be had in any way. The prisoners knew this much, but the fact that the words were there would have created a sense of hope within a hopeless situation. That is dehumanization based on psychological abuse. Telling fellow human beings that their lives are entirely dependent on the mercy of the Nazis and the subjugation they underwent is also dehumanizing.
Therefore deception dehumanizes by letting someone base their hopes, decisions, and emotions on falsehood.