Say I was talking to you and I told you one fact (like my name) and you wanted to memorize it, but we kept conversing. How would you do it?
You should rehearse it at T+8 seconds, 14 seconds, 32 seconds, 86 seconds, and increasing intervals in a 5+3^n pattern. Here's why:
Spaced Repetition has been around a long time. The idea is that, if you're going to practice a fact N times to remember it, you should practice it over time, not all at once. (this is called the Spacing Effect.) You should be asked to reproduce the item, not simply shown it again. ("Testing Effect") Furthermore, these rehearsals should be in increasing intervals. ("Expanded Retrieval")
About the spacing effect: this has been shown repeatedly (see pretty much any link in this post where spaced practice beats massed practice)
About the testing effect: this has been shown repeatedly too, e.g. by Carpenter and DeLosh (2005).
About expanded retrieval: this is a little less clear. Pimsleur (1967) suggested exponentially increasing intervals. Landauer and Bjork (1978) found that increasing intervals (e.g. rehearse in 1-5-9 seconds) is better than equally-spaced intervals (like 5-5-5) if you're testing yourself, but neither Carpenter and DeLosh (linked above) nor Balota et al (2007) found much support for the "increasing intervals is best" argument. Indeed, Karpicke and Roediger (2007) found that increasing intervals helped short-term recall, but equally-spaced intervals helped long-term recall. But they found that this effect may be due to the equally-spaced intervals' lack of an immediate recall (the "1" in a 1-5-9 schedule). They showed that just delaying the first test by 5 seconds makes it harder, which helps long-term recall. So it seems like you should be able to get the best of all worlds by adopting an increasing-intervals schedule, but also delaying the first review.
Another consideration is that this is the real world, not a 3-repetition study in the lab, and increasing intervals scales better. If you start practicing every 5 seconds, by the time you're at repetition 10 you'll be fed up, whereas if you go with 3-9-27-81 etc the intervals will quickly become so infrequent that you're not bothered.
But what should the first interval be? Peterson and Peterson (1959) show that recall percentage at 3 seconds is better than 6 seconds, 6 better than 9, etc., and we want them to remember it at the first interval, so might as well make the first interval 3 seconds. But, as Karpicke and Roediger (linked above) mentioned, we don't want it to be too easy to remember it at the first interval. Well, the same Peterson et al (1963) found 8 seconds to be the best interval.
So, how about a 3-9-27-81 interval plus 5 second delay, so 8-14-32-86-etc? Whew! Well, whatever; increasing + delayed-first-item sounds like at least a pretty good way to go.
Hmm... but if you're not in a lab, talking to an experimenter, how will you remember to test yourself at all these intervals? Hey, what if we could do that with a system using instant, unconscious, subtle microinteractions...
Stay tuned!
You should rehearse it at T+8 seconds, 14 seconds, 32 seconds, 86 seconds, and increasing intervals in a 5+3^n pattern. Here's why:
Spaced Repetition has been around a long time. The idea is that, if you're going to practice a fact N times to remember it, you should practice it over time, not all at once. (this is called the Spacing Effect.) You should be asked to reproduce the item, not simply shown it again. ("Testing Effect") Furthermore, these rehearsals should be in increasing intervals. ("Expanded Retrieval")
About the spacing effect: this has been shown repeatedly (see pretty much any link in this post where spaced practice beats massed practice)
About the testing effect: this has been shown repeatedly too, e.g. by Carpenter and DeLosh (2005).
About expanded retrieval: this is a little less clear. Pimsleur (1967) suggested exponentially increasing intervals. Landauer and Bjork (1978) found that increasing intervals (e.g. rehearse in 1-5-9 seconds) is better than equally-spaced intervals (like 5-5-5) if you're testing yourself, but neither Carpenter and DeLosh (linked above) nor Balota et al (2007) found much support for the "increasing intervals is best" argument. Indeed, Karpicke and Roediger (2007) found that increasing intervals helped short-term recall, but equally-spaced intervals helped long-term recall. But they found that this effect may be due to the equally-spaced intervals' lack of an immediate recall (the "1" in a 1-5-9 schedule). They showed that just delaying the first test by 5 seconds makes it harder, which helps long-term recall. So it seems like you should be able to get the best of all worlds by adopting an increasing-intervals schedule, but also delaying the first review.
Another consideration is that this is the real world, not a 3-repetition study in the lab, and increasing intervals scales better. If you start practicing every 5 seconds, by the time you're at repetition 10 you'll be fed up, whereas if you go with 3-9-27-81 etc the intervals will quickly become so infrequent that you're not bothered.
But what should the first interval be? Peterson and Peterson (1959) show that recall percentage at 3 seconds is better than 6 seconds, 6 better than 9, etc., and we want them to remember it at the first interval, so might as well make the first interval 3 seconds. But, as Karpicke and Roediger (linked above) mentioned, we don't want it to be too easy to remember it at the first interval. Well, the same Peterson et al (1963) found 8 seconds to be the best interval.
So, how about a 3-9-27-81 interval plus 5 second delay, so 8-14-32-86-etc? Whew! Well, whatever; increasing + delayed-first-item sounds like at least a pretty good way to go.
Hmm... but if you're not in a lab, talking to an experimenter, how will you remember to test yourself at all these intervals? Hey, what if we could do that with a system using instant, unconscious, subtle microinteractions...
Stay tuned!