The Spacing Effect

There is a finding in the scientific literature that's been known for over 100 years. Recent research has continued to support its existence, and it turns out to be one of the most robust effects ever discovered about memory and learning. The problem is, few people know about it. It's called: The Spacing Effect.

This effect was first described by Hermann Ebbinghaus, who discovered it while doing a series of experiments on his own memory. In short, he found that, although repetition helped him remember things, spacing the repetitions over time led to a big improvement in his ability to remember.

When you're studying, the spacing effects says that it's counterproductive to repeat what you've studied immediately after you've studied it once. Instead, you should actually let some time go by before you refresh your memories. How much time? That depends--when do you need to know the information? Here's the deal, taken from a study published in 2008:

When the gap between initial learning and test date was a week, the optimum review took place a day after initial learning... With a month gap, the ideal review occurred after about a week; with a year, the prime review came three weeks after learning.
So, midterms are roughly a month apart, right? That means you should be reviewing and repeating the material about every week.

The research shows that not only is spaced repetition a benefit to your remembering, but also that cramming is bad. Bad, bad, bad. Really bad. Did I mention it's bad? Optimally spaced repetition beat cramming by 77% to 111%. Note that a 100% improvement would mean a doubling of performance. Yeah, it's that good.

The bottom line: everyone should space out.

(For more, read the article, "Will that be on the test?" from the APS Observer.)

Why aren't you studying?


Heather said...

I think that "The Spacing Effect" is, ultimately, unrealistic for students who carry a full course load. When you have 5 courses, with 2 midterms in each - where do you find the time to review each course, every week? Oh and also read the textbooks and complete assignments, term papers, and labs? One things for sure, you can forget about having a life outside of school.

I agree with the findings of this report, but just because it is correct doesn't mean it is realistic to implement in your academics. That is, unless you want to be doing homework 30 hours of the day.

Anonymous said...

I agree with Heather to a point, but I have to point out that the Spacing effect is already something I've incorporated into my study habits.

I'll study something, then take a break and consciously avoid thinking about it for at least a couple of hours, but preferably a day. Then I'll sit back down and look over it again.

Heather is ultimately right, though. I find myself actually studying for something about a week before. This doesn't include the initial readings and note taking.

I've found that breaking up individual study sessions into theory and practice components helps space out content as well.

Anonymous said...

I have a quick question about the spacing effect. I understand that when the test date is in, say, a month you should review the material you learned after a week. But as the test date approaches and you learn new material, should you then shorten the period between learning and review accordingly?

Karsten A. Loepelmann said...

@Anonymous: There are a few "systems" out there that claim to have the right formula for how much to leave between learning sessions. I have not come across any definitive evidence to back up all the claims that are being made.

Learning and retention is going to depend on a lot of different interacting factors.

My advice is to keep testing your knowledge periodically. The "testing effect" is that practicing retrieving information can aid in consolidation. Don't spend too much of your time going over the same things again and again.

Hope this helps!

Anon 7:48 pm said...


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