system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: How can you train reflexes if they are involuntary reactions?

What the title says. How do those train your reflexes apps or websites work? Do they just help you process information faster?
gpt
Involuntary is a bit confusing here.  Reflexes occur without conscious thought.  There are also two types of reflexes - straight physical reflexes like when the doctor taps your knee and you kick, and reflexive responses when you react to a stimulus without thinking.  

You cannot train the response to a doctor tapping your knee.

You can train your response to general stimulus.  This done through repetition.   If you practice hitting a button when you hear a bell, eventually you will do that without having to consciously think about it.  That is a reflexive action.