I scored a 68 on the VVIQ and I can watch my pupils dilate in response to me 'seeing' something in my mind. It doesn't have to be a bright light in my mind's eye, I can imagine something that would trigger a fight or flight response and make the same thing happen.
Yeah this is another test they use: imagine something frightening and "normal people" will get clammy hands and elevated heart rates while aphantasics will not