"Sometimes people use “respect” to mean “treating someone like a person” and sometimes they use “respect” to mean “treating someone like an authority”
and sometimes people who are used to being treated like an authority say “if you won’t respect me I won’t respect you” and they mean “if you won’t treat me like an authority I won’t treat you like a person”
and they think they’re being fair but they aren’t, and it’s not okay."
-a 15yo autistic girl experiencing ABA therapy
The others have pretty much answered about it, but specifically, it's a very intense, very personal therapy, with some sessions lasting up to 8 hours. It's typically one-on-one with the therapist, who will be observing every behavior and rewarding behaviors that are desired. I haven't heard of any that do it around here, but I am sure some therapists 'punish' for behaviors that they do not want to see again.
As was noted in the other replies, it can be extremely demeaning to reduce a person to their behaviors alone, and a great abyss lies next to the feet of any therapist that easily conceals abusive or immoral practices... and those feet are on a slippery slope of scree.