Learning to Learn II – Learning Can Increase the Biological Capacity to Learn

I explained in my book on memory that the hippocampus is the brain structure that promotes consolidation of (declarative) short-term memories into long-term memories. I have also reviewed studies showing that the hippocampus is the one structure in the brain that clearly receives newborn nerve cells, even in the adult. New cells can enhance the ability of the hippocampus to create lasting memories. What has not been emphasized is the importance of survival of new neurons. To be of lasting benefit, new neurons must survive beyond just being born.

Insight into the requirements for neuron survival has come in a recent study by J. R. Epp and colleagues at the University of British Columbia. They injected rats with a chemical marker for DNA that shows up in any new DNA, that is in any newly born cells. If that marker shows up in a cell, it means that that this is a new cell that has incorporated the marker along with its new DNA.

Immediately after injection of the marker, the experimenters trained the rats in a large pool of water that had a safe platform located 2 cm under the water surface where rats could learn its location from seeing cues outside of the pool (such as windows, doors, pictures on the wall, etc.). Other studies had established that learning this task is accomplished by the hippocampus. Rats were divided into groups and trained on days 1-5, 6-10, or 11-15 after injection of the DNA marker. The new-DNA marker showed up only in rats trained on days 6-10 after marker injection. This indicated that there must have been new neurons in the hippocampus of these rats that did not survive in the two groups where marker was not seen. Put another way, for new neurons to survive there is a critical period where they have to be stimulated by learning experiences. Without that stimulus, they die.

Earlier studies had shown that new neurons in rat hippocampus have a development cycle wherein 6-10 days after birth is a middle stage of development in which new neurons are rapidly sending out membrane processes in search of contacts with other neurons. When neurons make contact with targets they can survive. The stimulus of learning thus provides a stimulus for forming new synapses with other neurons, thus enabling new neurons to survive.

The data were originally pooled across all rats in each test group. However, when the data were segregated by how well rats learned (the top and bottom 50 %), it became clear that it was only the poor learners that were showing an effect on new-neuron survival by maze learning. Poor learners probably got more stimulation from the learning because their brains had to work harder at it. It wasn’t that much of a mental challenge for good learners.

We know that humans are continually producing new neurons in the hippocampus. The issue is the need to experience enough demanding learning to help these new neurons survive. The critical period for learning to influence new-neuron survival in humans is not known. So, the practical take-home message is that we need to be learning constantly, every day, so that no matter what the critical period is, we will be helping our new neurons to survive. Survival of new neurons means a greater biological capacity for learning, at least in people who are not good learners. In other words, here is a clear case where the “poor get richer.”

Source: Epp, J. D., Spritzer, M. D., and Gales, L. A. M. 2007. Hippocampus-dependent learning promotes survival of new neurons in the dentate gyrus at a specific time during cell maturation. Behavioural Neuroscience. 149: 273-285.

Learn One Movement Skill At a Time

"Motor memory" refers to a mental model (MM) that the brain constructs from past experience. In the example given by researchers Reza Shadmehr and Thomas Brashara-Krug, when a person plans to pick up a brick, a MM of the amount of force required to pick up the brick is used to execute the action.The brain does not estimate the force as if it were a feather nor if it were a sack of cement, rather it uses its memory of what a brick weighs to create a model of how much force will be needed to pick it up.

In the studies they reported, they used a robotic arm that subjects used to manipulate objects. In learning how to use the mechanical arm, subjects had to create a MM of how to make it do what they wanted. Like other kinds of learning, the MM is consolidated with practice into long-term memory.Moreover, motor performance continues to improve, even after actual practice has stopped, indicating that the MM itself may be subconsciously rehearsed, off-line so to speak.

Motor memory processes have great applicability in everything from learning to touch-type to learning to throw a football to a moving target. The study by Shadmehr and Brashara-Krug explored the finding that a recently acquired MM (MM1) can be disrupted if a second MM (MM2) was introduced too soon after MM1.That is, a MM1 has to have enough time to consolidate, just as declarative memories do.

Also, a MM1 can interfere with learning a MM2, if there is not enough time separation between learning the two motor tasks.This was demonstrated in the present study by having 60 subjects learn how to make two conflicting movements using the robotic arm. The MM for both tasks could be learned but only if the training sessions were separated by at least 5 hours. If the interval was shorter, learning of the second MM (MM2) was impaired, as was the likelihood of consolidating the first MM.

The “take home message” of this research is that learning different movement tasks should be separated in time, lest there be interference with forming long-term memory of both tasks. My explanation is the following: Once MM1 gets consolidated (that is, after about 5 hours), the circuits that sustain its short-term representation now become available for learning a second motor memory (MM2). That is, MM1 has proactive interfering after-effects that dissipate with consolidation of the MM1 and thus no longer interfere with learning an MM2.

Athletic coaches might be well advised to ponder the application of this principle.


Shadmehr, R., and Brfashers-Krug, T. 1997. Functional stages in the formation of human long-term motor memory. J. Neuroscience. 17(1): 409-419.

Tests Produce Learning

Tests do more than just measure learning. Tests are learning events. That is, testing forces retrieval of incompletely learned material and that very act of retrieval helps to make the learning more permanent. Testing, and not actual studying, is the key factor on whether or not learning is consolidated into longer term memory.

A recent experiment by J. D.Karpicke and H. L. Roediger at Washington University in St. Louis, examined the role that retrieval had on the ability to recall that same material after a delay of a week. In the experiment, college students were to learn a list of 40 foreign language vocabulary word pairs, which were manipulated so that the pairs either remained in the list (were repeatedly studied) or were dropped from the list once they were recalled. It is like studying flash cards: one way is to keep studying all the cards over and over again; the other way is to drop out a card from the stack every time you correctly recalled what was on the other side of the card. In the experiment, after a fixed period of study time, students were tested over either the entire list or a partial list of only the pairs that had not been dropped. Four study and test periods alternated back-to-back. Students were also asked to predict how many pairs they would be able to remember a week later, and their predictions were compared with actual results on a final test a week later.

The initial learning took about 3-4 trials to master the list, and was not significantly affected by the strategy used (rehearsing the entire list or dropping items out as they were recalled). On average, the students predicted that they would be able to remember about half of the list on a test that was to be given a week later. However, actual recall a week later varied considerably depending on learning conditions. On the final test, students remembered about 80% of the word pairs if they had been tested on all the word pairs, no matter whether they had been studied multiple times with all of them in the list or if they dropped correctly recalled words from the list in later study trials. However, recall was only about 30% correct when correctly identified words were dropped from subsequent tests, even though all words were studied repeatedly. In other words, it was the repeated testing, not the studying, that was the key factor in successful longer-term memory.

So, what is the practical application? When using flash cards, for example, you need to follow each study session (whether or not you drop cards from the stack because you know them), with a formal test over all the cards. Then, repeat the process several times, with study and test epochs back-to-back. Can we extend this principle of frequent testing to other kinds of learning strategies? Probably. But there are no formal experiments.

Let us speculate on the case of trying to remember names of people at a party. You might study the name of each person by using it in conversation or associating the name with some feature of the person's anatomy or personality. Then, silently quiz yourself, looking at the person and asking yourself to recall the person's name. Then, repeat the study-and-test process several times. You would have to keep number of people low (say four to six), because you may not have many opportunities to hear the name repeated other than your own repeating it in conversation. In most practical learning situations, you will not be given repeat tests immediately after each study session, so you must simulate that with self-tests.

Why does forced recall, as during testing, promote consolidation? It probably relates to other recent discoveries showing that each time something is recalled the memory is re-consolidated. If the same information is consolidated again and again, the memory is presumably reinforced.

The failure of students to predict how well they would remember is consistent with my 40 years experience as a professor. Students are frequently surprised to discover after an examination that they did not know the material as well as they thought they did. Tests not only reveal what you know and don't know, they serve to increase how much you eventually learn. If I were still teaching, I would give more tests. And I would encourage students to use self-testing as a routine learning strategy, something that one study revealed to be a seldom-used strategy. The repeated self-tests should include all the study material and not drop out the material that the student thinks is already mastered.

Source: Karpicke, Jeffrey D., and Roedinger, Henry L. III. 2008. The critical importance of retrieval for learning. Science. 319: 966-968.

Overtraining: You Can Learn Too Much

Naps may be helpful for learning tasks other than those involving movement (see earlier note on work by Korman et al.).* An early study on the effects of napping had developed a useful texture discrimination task in which a visual display of horizontal bars has superimposed on it a brief display of three diagonal bars, followed by a blank screen, and then by a mask. The interval between the target and the mask is varied and the interval needed to achieve 80% correct responses is used as a measure of perceptual ability and working memory.

After a single training session, performance on this task improves only after subjects have had a normal night's sleep after the day's training. To be effective, a normal amount of dream sleep, which occurs mostly in early morning, is needed.

In a follow up study by another investigator, subject performance unexpectedly deteriorated if they were given 60-minute training sessions four times at regular intervals on the same day. In other words, the more the subjects were trained, the poorer they performed. However, this interference did not occur if subjects were allowed to nap for 30-60 minutes between the second and third sessions.

It is hard to explain why over-training disrupts performance, but one has to suspect that as training trials are repeated the information starts to interfere with memory consolidation, perhaps because of boredom or fatigue in the neural circuits that mediate the learning. Napping must have a restorative function that compensates for the negative effects of overtraining. What all this suggests to me is that memory consolidation would be optimized if learning occurred in short sessions that are repeated but only with intervening naps and on different days with regular night-time sleep. In other words, repeating long study periods in the same day on the same task can be counter-productive. This is yet another reason why students should not cram-study for exams. Learning should be optimized by rehearsing the same learning material on separate days where normal sleep occurred each night.

See my book on what science reveals about improving everyday memory. I also give seminars and workshops.

Sources:

Maquet, P. et al. 2002. Be caught napping: you're doing more than resting your eyes.Nature Neuroscience. 5 (7); 618-619.

Mednick, Sara, et al. 2002. The restorative effect of naps on perceptual deterioration.Nature Neuroscience. 5 (7): 677-681.

Improve Reading Efficiency and Comprehension

Reading To Remember

Get the mechanics right

○ Make eye contact with all the text not being deliberately skimmed
○ See multiple words in each eye fixation
○ Strive to expand the width of each eye fixation (on an 8.5" width, strive
for three fixations or less per line)
○ Snap eyes from one fixation point to another (horizontal snaps on long
lines, vertical snap if whole line can be seen with one fixation)
○ Get formal training from a reading center if needed

Strategy

○ Know what you are looking for. Identify the material that satisfies the purpose for which you are reading.
○ Skim the reading material first

• primes the memory
  
• orients the thinking
  
• think about the headings: they identify what can be skimmed rapidly, what needs more thoughtful reading
  

Tactics

○ Read with a purpose.
○ THINK about what you read. The more you think about it, the more you will remember. Ask yourself questions about what you read, as you are reading and afterward.

• Is it satisfying your purpose?
  
• How does it relate to what you already know? ... and need to know?
  
• What is not said that should be?
  
• What is said that you think is wrong or needs elaboration?
  
• What do you not understand?
  
• What needs special effort to remember?
  
• How can you use this understanding and information?
  

○ Pause and rehearse (after every minute or so, for example)
○ For each new reading segment, ask “How does this build on what I just read?”
○ Reading sessions should be limited (15 to 30 minutes)
○ At the session end, rehearse what you learned - right away, without distractions. Answer again the questions mentioned above.
○ Think about and rehearse what you read at least twice later that day.
○ Rehearse again at least once for the next 2-3 days.

Computer Slide Shows. A Trap for Bad Teaching

Teachers at all grade levels are increasingly using computer slide shows (like MS PowerPoint shows) to present information. Such slide shows are also common in corporate and government briefings. Such slide shows typically violate many of the principles for good remembering. In this article, published in the education journal, College Teaching, I explain what slide shows typically do wrong and suggest ways to make the content of slide shows more memorable. Click here to read.

What Good Is Learning If You Don't Remember It

I had a paper published in Journal of Effective Teaching that I hope teachers will take a look at. It can be found on-line by clicking here.

Here is the abstract:

Teachers should emphasize the educational importance of understanding, but not at the expense of overlooking the importance of memorization skills. Currently, mainstream educational theory embraces such attributes as insight, creativity, inquiry learning, and self expression. But such emphases lead to a bias and under-appreciation of the role of memory in learning. Students cannot apply what they understand if they don’t remember it. Moreover, a good memory expands the repertoire of cognitive capabilities upon which new understandings can be developed and expedited. Effective thinking does not occur in a vacuum. I advocate adding another “R” to the “three Rs”: Reading, wRiting, aRithmetic, and Remembering. This paper attempts to show teachers how they can help students become better learners — and better thinkers — by improving their memorization skills.

Please comment.

Seven Tips for Learning from Lectures:

In this post I list seven tips you can use when trying to remember the contents of a seminar or lecture. These tips are especially useful for students. Forty-three years of college teaching have made it clear that most students don't get as much out of lectures as they should (and it is not just because of my lectures). When I was a student, I wanted to learn efficiently, so I could have more play time. I soon discovered that everything I could learn in class was something I did not have to study later.

The basis for these tips comes from my book on improving memory and from the posts in this blog. Obviously, I can't review all that here. Take my word for it, these tips work. Please comment to tell me what you have learned about learning effectiveness and efficiency during lectures.

The Tips:

1. Come with the right attitude. Be pumped up. Plan to retain as much understanding and information as possible. As long as you are spending your time in class, you might as well get out of it all you can. Don't be willing to put off the learning until later study time.

2. Do at least a little pre-lecture preparation. Skim text or other sources that deal with the topic of the day. If lectures are inter-related, briefly review previous notes of lectures that this current lecture will build on.

3. Don't take many notes. Take notes only for organizing ideas and for things you don't already know or could figure out. Use a tape recorder if you worry about missing something.

4. Make notes with multiple visual and spatial cues. Use lots of drawings and diagrams.

5. If allowed, ask questions of the teacher. This helps to keep you alert and engaged. Remember the answer. If you have asked good questions, they are liable to show up on quizzes (teachers like to quiz on ideas that come up in class that are not in the book or handouts - its a reward for those who attend and pay attention).

6. THINK about what is being said by the teacher. How does this build on what has been presented in the course earlier? What issues are not getting addressed by this lecture? What is most likely to show up on a quiz? What will take special effort to remember? How can you use this information, either later in this course or in another course?

7. After the lecture:

a. Don't do anything for the next 10 minutes. Without interruption, review what has just transpired, first by looking at your notes, then trying to recall without lookng.

b. Re-work your notes and drawings if they need it.

c. Assuming your handwriting is readable, keep the longhand version of your notes. See in your mind's eye the spatial layout of the notes; recall it as you would a photograph. Cursive handwriting and the hand drawings provide many visual and spatial cues that will facilitate
memory.

d. Come back later that same day for another rehearsal of what transpired in class, first by looking at your notes, then by not looking at them. Vocalize your notes; hearing the information will reinforce the retention especially for auditory learners. Repeat this review in each of the next several days.