For me, it is "new browser tab" effect these days. I will often be reading a website, then think "Oh, I must research this thing they are talking about" or else I will remember some other thing that I have to do online, so I will open a new browser window in the background.

But then I will get distracted by something else on the current web page - for even a few seconds - and when I go to the new tab to do what I had planned to do, I sit there in complete blank befuddlement, staring at the empty page and wondering what on earth I was supposed to look up.