An ability to visualise to a ‘clear and lively’ level in my mind’s eye, various scenes as set out in this article about ‘Vividness of Visual Imagery’. I ticked the boxes in the article fairly rapidly, but will do the test again at night to see any difference. I shall do this test again at other times because I feel that I’m of a higher level – ‘perfectly realistic, as vivid as seeing’ – ‘Hyperphantasia’ - but can’t be sure right now.
This is part of an interesting set of articles in the Guardian about the brain.
Look under ‘related stories’.