I don't know anything about aspergers or autism, but memory fascinates me. My cousin was in a road crash some years back and had a serious head injury. After about 72 hours unconscious, he came round and thankfully seemed OK, but we quickly discovered his short term memory was screwed up. You could visit mid-morning and he could remember what he'd had for dinner the day before, but not a clue what he'd had for breakfast. The doctors used an analogy that your memory is like a filing cabinet. One drawer is for short term use, and all the others are for long term. He couldn't access the short term. But they also said that the others are essentially infinite capacity, and everything you 'remember' - facts, sounds, smells, visual, etc. gets filed for future reference. The trouble is that the filing system is shit, so trying to find stuff that you don't look for often, and hence know what drawer it's in, becomes very hard. But that's where these memory triggers come from, they're sort of the filing reference system that takes you immediately to a particular file in a particular drawer of these infinite drawers.