Forget the memory-boosting pills: In the future, powers of recall could be boosted with programs on a handheld PDA.

Researchers have found a telltale mental signature that predicts whether an experience will be remembered. Once deciphered, the signals could be used to help people know when their brains are primed to remember, perhaps using an iPhone app.

"Instead of looking at how the information is being processed, we're looking at how the brain prepares to process the information,"

the new study, in Proceedings of the National Academies of Science on Monday, shows a signal that appears to precede the formation of any memory type. It could be an all-purpose memory switch, determining when the brain enters a favorable encoding state, roughly akin to the overwrite tab on an old-fashioned floppy disk.