Optimal Spacing for Study, What's this?

We have all been told by teachers that learning occurs best when we spread it out over time, rather than trying to cram everything into our memory banks at one time. But what is the optimal spacing? There is no general consensus.

However we do know that immediately after a learning experience the memory of the event is extremely volatile and easily lost. It's like looking up a number in the phone book: if you think about something else at the same time you may have to look the number up again before you can dial it. School settings commonly create this problem. One learning object may be immediately followed by another, and the succession of such new information tends to erase the memory of the preceding ones.

Memory researchers have known for a long time that repeated retrieval enhances long-term retention. This happens because each time we retrieve a memory, it has to be reconsolidated and each such reconsolidation strengthens the memory. Though optimal spacing intervals have not been identified, research confirms the importance of spaced retrieval. No doubt, the nature of the information, the effectiveness of initial encoding, competing experiences, and individual variability affect the optimal interval for spaced learning.

One study revealed that repeated retrieval of learned information (100 Swahili–English word pairs) with long intervals produced a 200% improvement in long-term retention relative to repeated retrieval with no spacing between tests. Investigators compared different-length intervals of 15, 30, or 90 minute spacing that expanded (for example, 15-30-45 min), stayed the same (30-30-30 min) or contracted (45-30-15 min) revealed that no one relative spacing interval pattern was superior to any other.

Another study has revealed that the optimally efficient gap between study sessions depends on when the information will be tested in the future. A very comprehensive study of this matter in 1,350 individuals involved teaching them a set of facts and then testing them for long-term retention after 3.5 months. A final test was given at a further delay of up to one year. At any test delay, increasing the inter-study gap between the first learning and a study of that material at first increased and then gradually reduced final test performance. Expressed as a ratio, the optimal gap equaled 10-20% of the test delay. That is, for example, a one-day gap was best for a test to be given seven days later, while a 21-day gap was best for a test 70 days later. Few of any teachers or students know this, and their study times are rarely scheduled in any systematic way, typically being driven by test schedules for other subjects, convenience, or even the teacher's whim.

The bottom line: the optimal time to review a newly learned experience is just before you are about to forget it. Obviously, we usually don't know when this occurs, but in general the vast bulk of forgetting occurs within the first day after learning. As a rule of thumb, you can suspect that a few repetitions early on should be helpful in fully encoding the information and initiating a robust consolidation process. So, for example, after each class a student should quickly remind herself what was just learned—then that evening do another quick review. Before the next class on that subject, the student should review again. Teachers help this process by linking the next lesson to the preceding one.

Certain practices will reduce the amount of time needed for study and the degree of long-term memory formation. These include:

• Don't procrastinate. Do it now!

• Organize the information in ways that make sense (outlines, concept maps)

• Identify what needs to be memorized and what does not.

• Focus. Do not multi-task. No music, cell phones, TV or radio, or distractions of any kind.

• Association the new with things you already know.

• Associate words with mental images and link images to locations, or in story chains

• Think hard about the information, in different contexts

• Study small chunks of material, in short intervals. Then take a mental break.

• Say out loud what you are trying to remember.

• Practice soon after learning and frequently thereafter at spaced intervals.

• Explain what you are learning to somebody else. Work with study groups later.

• Self-test. Don't just "look over" the material. Truly engage with it.

• Never, never, ever CRAM!

Sleep in Your bad attitude, avoid!!

Generally speaking, you cannot learn from sounds of new information while you sleep, though this was a fad several decades ago. But in an earlier post, I discussed a new line of research where sleep learning can occur. The key is to play sound cues that were associated with learning that occurred during the previous wakefulness period. The explanation I posted was that cue-dependent sleep learning can work because a normal function of sleep is to strengthen memories of new information and that presenting relevant cues during sleep increases the retrieval of these memories and makes them accessible for rehearsal and strengthening.

The latest experiment by a different group shows that this cuing during sleep can modify bad attitudes and habits. The test involved counter stereotype-training of certain biased attitudes during wakefulness, and investigators reactivated that counter-training during sleep by playing a sound cue that had been associated with the wakefulness training.

In the experiment, before a 90-minute nap 40 white males and females were trained to counter their existing gender and racial biases by counter-training. A formal surveyed allowed quantification of each person's level of gender or racial bias before and after counter-training. For example, one bias was that females are not good at math. Subjects were conditioned to have a more favorable attitude about women and math with counter-training that repeatedly associated female faces with science-related words. Similarly, racial bias toward blacks was countered by associating black faces with highly positive words. In each training situation, whenever the subject saw a pairing that was incompatible with their existing bias they pressed a "correct" button, which yielded a confirmatory sound tone that was unique for each bias condition. Subjects were immediately tested for their learning by showing a face (female or black) and the counter-training cue, whereupon they were to drag the appropriate bias-free face on to a screen with the positive word. For example, if the first test screen was that of a woman, accompanied by the sound cue, the subject dragged a woman's face onto a second screen that said "good at math." Results revealed that this conditioning worked: both kinds of bias were reduced immediately after counter-conditioning.

Then during the nap, as soon as EEG signs indicated the presence of deep sleep, the appropriate sound cue was played repeatedly to reactivate the prior learning. When subjects re-took the bias survey a week later, the social bias was reduced in the sound-cued group, but not in the control group that was trained without sound cues.

Experimenters noted that the long-term improvement of bias was associated with rapid-eye-movement (REM) (dream) sleep which often followed the deep sleep during early stages of the nap. That is, the beneficial effect was proportional to the amount of nap time spent in both slow-wave sleep and REM sleep, not either alone. It may be that memories are reactivated by cuing during deep (slow-wave) sleep, but that the actual cell-level storage of memory is provided by REM sleep.

Implications of this approach to enhancing learning and memory show a great deal of promise. Can it be used for enhancing learning in school? Can it be used in rehabilitation of addicts or criminals? But there is a dark side. Now might be a good time to re-read Huxley'sBrave New World wherein he actually described conditioning values in young children while they slept. Sleep is a state where people are mentally vulnerable and without conscious control over their thoughts. Malevolent people could impose this kind of conditioning and memory enhancement on others for nefarious purposes.  These techniques may have valid social engineering applications, but they must be guided by ethical considerations.

How Schools Make Learning Harder Than Necessary

Keep your "nose to the grindstone" is the advice we often give as an essential ingredient of learning difficult tasks. An old joke captures the problem with the old bromide for success, "Keep your eye on the ball, your ear to the ground, your nose to the grindstone, your shoulder to the wheel: Now try to work in that position."

Over the years of teaching, I have seen many highly conscientious students work like demons in their study yet don't seem to learn as much as they should for all the effort they put in. Typically, it is because they don't study smart. And sometimes the problem is created by the teachers' method of instruction.

In an earlier post, I described a learning strategy wherein a student should spend repeated short (say 10-15 minutes) of intense study followed immediately by a comparable rest period of "brain-dead" activity where they don't engage with a new learning task. The idea is that memory of the just-learned material is more likely to be consolidated into long-term memory because there are no mental distractions to erase the temporary working memory while it is in the process of consolidation.

Now, new research now suggests that too much nose-to-the-grindstone can impair learning.

Margaret Schlichting, a graduate student researcher, and Alison Preston, an associate professor of psychology and neuroscience at the University of Texas tested the effect of mental rest with a learning task of remembering two sets of a series of associated photo pairs.  Between the two task sets, the participants rested and were allowed to think about whatever they wanted. Not surprisingly, those who used the rest time to reflect on what they had learned earlier were able to remember more upon re-test. Obviously, in this case, the brain is not really resting, as it is processing (that is, rehearsing) the new learning. But the brain is resting in the sense that no new mental challenges are encountered.

The university press release quotes the authors as saying, "We've shown for the first time that how the brain processes information during rest can improve future learning. We think replaying memories during rest makes those earlier memories stronger, not just impacting the original content, but impacting the memories to come." Despite the fact that this concept has been anointed as a new discovery in a prestigious science journal, the principle has been well-known for decades. I have explained this phenomenon in my memory books as the well-established term of "interference theory of memory,"

What has not been well understood among teachers is the need to alter teaching practices to accommodate this principle. A typical class period involves teachers presenting a back-to-back succession of highly diverse learning objects and concepts. Each new topic interferes with memory formation of the prior topics. An additional interference occurs when a class period is disrupted by blaring announcements from the principal's office, designed to be loud to command attention (which has the effect of diverting attention away from the learning material). The typical classroom has a plethora of other distractions, such as windows for looking outside and multiple objects like animals, pictures, posters, banners, and ceiling mobiles designed to decorate and enliven the room. The room itself is a major distraction.

Then, to compound the problem, the class bell rings, and students rush out into the hall for their next class, socializing furiously in the limited time they have to get to the next class (on a different subject, by a different teacher, in a differently decorated classroom). You can be sure, little reflection occurs on the academic material they had just encountered.

The format of a typical school day is so well-entrenched that I doubt it can be changed. But there is no excuse for blaring loudspeaker announcements during the middle of a class period. Classrooms do not have to be decorated. A given class period does not have to be an information dump on overwhelmed students. Short periods of instruction need to be followed by short, low-key, periods of questioning, discussion, reflection, and application of what has just been taught. Content that doesn't get "covered" in class can be assigned as homework—or even exempted from being a learning requirement. It is better to learn a few things well than many things poorly. Indeed, this is the refreshing philosophy behind the new national science standards known as "Next Generation Science Standards."

Give our kids a rest: the right kind of mental rest.

Sources:


Schlichting, M. L., and Preston, A. R. (2014). Memory reactivation during rest supports upcoming learning of related content Proc. Nat. Acad. Science. Published ahead of print October 20, 2014.

http://scicasts.com/neuroscience/2065-cognitive-science/8539-study-suggests-mental-rest-and-reflection-boost-learning/

http://www.nextgenscience.org/

Dr. Klemm's latest book, available at most retail outlets, is "Mental Biology. The New Science of How the Brain and Mind Relate" (Prometheus).