Overlearning makes new memories last longer

I may owe a few teachers an apology. It turns out the seemingly endless math worksheets I remember in elementary school may have been doing more for my education besides eating hours in the day. According to a concept called “overlearning,” practicing a skill that I was already learned likely helped cement new information in my mind in a more durable way than practicing only to the point of comprehension. It may not have had the excitement of novelty, but at least I was likely to retain the fruits of all that dull labor.

Practicing beyond perfect

In a more focused, experimental setting than my fourth grade classroom, researchers tasked test participants with finding and recognizing a stripe pattern among visual noise. It generally took people around 20 minutes to become adept at this task, but were asked to continue for an additional 20 minutes beyond that in a period of overlearning. Participants then took a short break before doing a different but very similar task, basically looking for a different stripe pattern. People could pick up the second skill without difficulty, but the real test was how much they could remember the next day.

The fact that the two tasks were so similar, and done more or less back-to-back, meant that the brain was likely to put them in competition with each other for space in the participants’ memory. Normally, doing both tasks just enough to “learn” them would mean that people would struggle to retain their morning stripe-finding skills. However, participants that spent that additional 20 minutes to overlearn the first stripe pattern had the opposite outcome— on the next day, they could only remember the first pattern.

A rough analogy would be to look at your memory as a piece of modeling clay. Normal learning sculpts that clay into a specific shape, but if a second, very similar task requiring the same clay is then started, you’re left reworking that same clay again. The first sculpture only has a chance to set and harden into what’s known as a “resilient” memory if you overlearn it, giving it time to really take hold, even at the cost of memories of the next task. The major alternative to overlearning is a natural process we do every night— sleep.

Resetting the system

In many scenarios, we probably don’t worry about reworking an losing similar memories because they’re not packed too closely together chronologically. A night’s sleep helps save whatever information, or sculpted clay, we worked on during the day, preserving it and giving us a blank slate of grey matter to work with at our next lesson.

In the case of overlearning, a variation on the stripe-detection test found that taking a break for several hours after an overlearned stripe-hunting session could sort of substitute for sleep. It wasn’t as effective a shut-eye, but the break seemed to allow the brain to recuperate for the second session. Participants on this schedule were able to remember both stripe patterns the next day, suggesting that if you have the time (and the worksheets?) you don’t have to sacrifice one set of memories for the other.

Source: The Power of Overlearning by Victoria Sayo Turner, Scientific American