"It filled me with panic, but I never had in my mind that it was a stroke. He sat me down and was like, 'You've had an infarct in your left occipital lobe'. I asked 'What's that in English?' ...

Aphantasia is a little-understood phenomenon that affects about 4 percent of the population. There are several theories behind what causes it.

"It filled me with panic, but I never had in my mind that it was a stroke. He sat me down and was like, 'you've had an infarct in your left occipital lobe'. I asked 'what's that in English?' ...