Roger Rowe asked:
Why do smells trigger memories? It seems to be true both for perfumes and other less pleasant odours; they can both make me remember things that happened.
Greg Jefferis - I think there's a bit of debate there. There's certainly a fairly direct connection between the olfactory system, starting at the nose, and parts of the brain involved in storing and recalling memories. Whether that very direct connection is important to this thing that we often feel or hear about, of odours triggering memories very selectively, I'm not so sure.
Another view would be that smells are just very specific things and that's why they are able to trigger a very specific memory, picked out from everything that's in your brain. So I guess there are two possible ideas there.