Close your eyes and picture an apple. Most people see something-a faint, slightly blurry image, less vivid than a real apple. A few, however, will see it as clearly as if it were sitting right in front of them. This ability is called hyperphantasia. Hyperphantasia, literally meaning "beyond imagination," refers to exceptionally vivid mental imagery. It is often described as the opposite of aphantasia, a condition in which people report little or no ability to form mental images.
You know that ache you get when you stumble across evidence of your past self being genuinely, effortlessly happy? It's not that you want to go back. Not really. I think what kills you is the proof staring back at you - proof that you were once capable of feeling that alive, that connected, that certain about where you belonged in the world.
Did someone with spatial-sequence synaesthesia design the calendar app on mobile phones? Because that's how time and dates look in my brain. If you say a date to me, that day appears in a grid diagram in my head, and it shows if that box is already imprinted with a holiday, event or someone's birthday. Public holidays and special events like Christmas and Easter are already imprinted for the year, and the diagram goes backwards to about 100,000BC