Long-time readers of this blog (as if!) will know I admire Dretske's 'Knowledge and the flow of information'. It turns out that as well as an excellent writer he's a great speaker, as I found from his 2007 Howison Lecture at UC Berkeley, on 'What we see' - embedded below.
He's arguing that we DO see the rich complexity of things, even though we don't realise it. One aspect of his line of argument is that you don't have to think about something actively to know it.
Q: Were there any giraffe's in your bedroom when you got up this morning?
A: You most likely know there weren't even though you didn't actively think about it.
This is interesting, and some other examples he gives - with some nice illustrations using complicated images - probe it further, but I'm not 100% convinced.
In the questions at the end, someone asks about the gorilla in the famous video:
(An earlier version of this idea here: http://viscog.beckman.illinois.edu/flashmovie/15.php)
Dretske argues that those of us who think we didn't see the gorilla, probably did know something about it, which could be revealed if we were asked the right question. Well, maybe, but surely if we'd seen it we would have been actively aware of it, something as out of place as that? It seems a bit of 'clincher' to me!
PS: Here's another one in the same vein: