Imagine an apple on a table.

Did you do it?

What kind of apple was it? What was the tabletop made of?

I understand there’s an apple on a table, and I have an idea of it, but it’s hugely abstract. There’s no specificity to any of it.

Apparently “normal” people have a very definite image in mind for this test.

It’s called aphantasia, I think, if you want to learn more.