Voluntary responses are mainly under your control, while an involuntary reaction happens without someone knowing they're actually doing it. This can play a role in ignorance by for example, if someone is Muslim and a person involuntarily scoots away from them or gives them a hurtful glance. Which they could not realize they're being rude and even not realize they are doing it, it's just what they do from that learned habit.
Hope this helps! If you need a different example, let me know! :-)
