system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to cause the delay when I hear someone but don't understand, then say "what?", but before they answer/repeat themselves I realize what they said from the first time around?

It happens to me from time to time - that part in a conversation where you hear someone but I feel like I didn't hear them or understand what they said.  Then you say "What?" indicating for them to repeat themselves, but before they say anything you realize what they said.  I'm curious what causes that second or two delay in hearing someone and understanding them sometimes.  Is it just our brains deciphering context or something?  Or maybe something not working 100% right?  Thanks ever so much.
gpt
Your brain does lots of things in parallel. So one part of your brain didn't catch or understand what was said and triggered you to say 'What?'. But another part of your brain was still working on it, and that part delivered the results, a half-second too late.

Quite often, as you are listening, you don't catch the order of the words. From the start of the sentence, you are expecting one thing, but the end of the sentence goes elsewhere. Your brain needs a moment to reconsider the sentence from the beginning.

It's nothing wrong - indeed, it is your brain working correctly. It happens to everyone - almost every time one of your friends asks you, 'What?'. If they are a good friend, wait half a second, and ask them if they really need you to repeat themselves. You'll probably be surprised!