Earlier quoted context omitted.
fMRI can probably spot it for people like myself who are fully aphantasic. But: 1. "Imagine a table. There is a ball on the table. The ball rolls off the table onto the floor." 2. "From memory, what color was the ball? The table? The floor? What did you see under the table?" Neither I nor any other, uh, aphants, that I have known have answers to those questions. Imagination still works, and answers to those questions…
"mind's eye" is a metaphor. You, like everyone else, have two eyes, in the front of your face. There isn't an extra one embedded in anyone's brain.
https://en.wikipedia.org/wiki/Pineal_gland#Society_and_cultu...