Being put on the spot

My brain processes things slower than some people’s. This is an introvert trait. When I am suddenly put on the spot...out of the blue to have to answer a particular question right away...then it takes me awhile for my brain to kick in to be able to answer the question and then it appears that I don’t know anything about the subject, when in fact that I do, given the time to think and process. I hate that I am put on the spot like that...it really drains me.