inattentional blindness

Inattentional blindness is missing something in plain sight because your attention was spent elsewhere — the gorilla walking through the basketball game that half the counting viewers never see.

It is not a failure of the eyes but of the attention budget: what is not attended is often not experienced at all. It matters here because it is the measurable opposite of noticing — and a brief mindfulness induction reduces it, which is the hardest evidence the castle has that the noticing stance can be trained (the-noticing-stance).