extreme learning: overcoming the spacing effect
May 20, 2008
Gary Wolf writes in Wired a fascinating story of Piotr Wozniak’s quest for an effective method of learning that he has built into his SuperMemo software (via Chris Pettit, who recommends Mnemosyne, open source software based on the same algorithm which will run on a Mac). While I’m not sure I’m ready to dive into this technique, I loved reading about Wozniak’s passionately focused approach along with Wolf’s detailed background on scientists who have studied how we remember and forget.
In the late 1800s, a German scientist named Hermann Ebbinghaus studied memory by repeated experiments of how long it took to learn (and remember or forget) a series of nonsense words. “Ebbinghaus discovered many lawlike regularities of mental life. He was the first to draw a learning curve. Ebbinghaus showed that it’s possible to dramatically improve learning by correctly spacing practice sessions.” He called this phenomenon the spacing effect.
Robert and Elizabeth Bjork, professors of psychology, sought to understand the spacing effect more recently. They noted a “paradoxical tendency of older memories to become stronger with the passage of time, while more recent memories faded… Long-term memory, the Bjorks said, can be characterized by two components, which they named retrieval strength and storage strength. Retrieval strength measures how likely you are to recall something right now, how close it is to the surface of your mind. Storage strength measures how deeply the memory is rooted. Some memories may have high storage strength but low retrieval strength.”
“One of the problems is that the amount of storage strength you gain from practice is inversely correlated with the current retrieval strength. In other words, the harder you have to work to get the right answer, the more the answer is sealed in memory. Precisely those things that seem to signal we’re learning well — easy performance on drills, fluency during a lesson, even the subjective feeling that we know something — are misleading when it comes to predicting whether we will remember it in the future.”
“It is a common intuition,” Wozniak later wrote, “that with successive repetitions, knowledge should gradually become more durable and require less frequent review.” Wolf details Wozniak’s life study of how to remember effectively through refreshing that knowledge in the moment just before you are about to forget it. He adjusted this technique over many years, applying it to whatever he was studying: English vocabulary, facts from biology, and eventually anything he wanted to read. All of his early work was done on paper. It was in the day of the punch card, and lines to computer use at his university made automating the process impractical. Later he got a friend to encode his technique into Atari software and it is now available on Windows and Palm. SuperMemo allows you to enter a series of Flash Cards which it will present to you in intervals which are optimized for your learning.
At the end of the article, Gary Wolf writes, “philosopher William James once wrote that mental life is controlled by noticing. Climbing out of the sea and onto the windy beach, my skin purple and my mind in a reverie provoked by shock, I find myself thinking of a checklist Wozniak wrote a few years ago describing how to become a genius. His advice was straightforward yet strangely terrible: You must clarify your goals, gain knowledge through spaced repetition, preserve health, work steadily, minimize stress, refuse interruption, and never resist sleep when tired.”
Awesome advice, but either I’ll never be a genius or I’m taking a significantly different path :)