More Evidence that Naps Help Memory

I have mentioned before the value of naps for improving the formation of memories. Another recent student confirms this conclusion. Matthew Walker and colleagues an the University of California at Berkeley divided 39 young adults into two groups. At noon, all the participants took part in a memory exercise that required them to remember faces and link them with names. Then the researchers took part in another memory exercise at 6 p.m., after 20 had napped for 100 minutes during the break.

Those who remained awake performed about 10 percent worse on the tests than those who napped, Walker said. Students take note: 10% can be the difference between an A and a B.

Source: Walker, Mathew. 2010. Current Models of Mechanisms of Sleep-Dependent Memory Presentation at the annual meeting of the American Association for the Advancement of Science meeting, San Diego, Feb. 21.

More on the Benefits of Blueberries

In several earlier posts, I discussed experiments that indicate blueberries can improve memory. There is a more recent study in 9 older adults (average age was 76) who were showing early signs of deterioration in memory capability. For 12 weeks, the subjects were given daily doses approximately 2.5 cups (exact amount adjusted according to body weight) of juice made from commercially available frozen wild blueberries. Berries were thawed, pressed, filtered, pasteurized, and then bottled. A comparison group drank the same amount of fake blueberry juice.

The subjects were instructed to refrigerate the juice at home and to take prescribed daily quantities in equal, divided dosages with the morning, midday, and evening meals. Memory tests (word-pair association, word list) were given before and after the test period. Significant gains in memory ability were seen in the blueberry group. Scores on both kinds of memory tests increased about 33%.

Additionally, there was suggestive evidence that blueberry juice reduced signs of depression and lowered blood glucose levels. This needs to be pursued in future research.

In an earlier post I had summarized a study that showed that milk protein interfered with the blueberry effect. Presumably other proteins could also interfere. In other words, I am suggesting that even better results might be obtained if the juice is taken on an empty stomach (assuming of course that this does not cause upset stomach).

The beneficial effects of the blueberries are thought to be linked to their flavonoid content - in particular anthocyanins and flavanols. The exact way in which flavonoids affect the brain are unknown, but they have previously been shown to cross the blood brain barrier after dietary intake.

Source:
Krikorian, R. et al. (2010) Blueberry supplementation improves memory in older adults. J. Agricultural and Food Chemistry. doi: 10.1021/jf9029332

What's the Right Amount of Homework?

When I ran for election to my local school board, one of my campaign planks was to promote homework. I lost. Many parents objected to my platform, often because homework would interfere with their kids' extracurricular activities or with their part-time job. One parent said to me, "We don't want any homework. My son needs that time to work at his job." I asked, "Why does he need to work?" She said, "Well, to pay for his truck for one thing." "Why does he need a truck?" I asked. Her reply: "Well, you dufus, to get to his job!"

A Duke University neuroscientist, Harris Cooper, posted in The Sacremento Bee on Jan. 17, 2010 some of his findings from research on this topic. He pointed out that an earlier Associated Press poll found that 57% of parents thought their kids got about the right amount of homework. Another 23% thought there was too little homework and 19% thought there was too much.

Harris was interested, not so much in parent opinion, but about the question of whether or not homework helps test performance. When he and his helpers looked at various published homework studies, they found that the effect varied by grade level. Comparing students who were assigned homework with students assigned no homework but who were similar in other ways suggested that homework can improve students' scores on the class tests that come at the end of a topic. Students assigned homework in second grade did better on math, third- and fourth-graders did better on English skills and vocabulary, fifth-graders on social studies, ninth- through 12th-graders on American history and 12th-graders on Shakespeare.

He finds that practice assignments do improve scores on class tests at all grade levels. A little amount of homework may help elementary school students build study habits. Homework for junior high students appears to reach the point of diminishing returns after about 90 minutes a night. For high school students, the positive line continues to climb until between 90 minutes and 2 1/2 hours of homework a night, after which returns diminish.

What nobody seems to have studied is the question of what kind of homework is most effective. Options include busy work such as filling out work sheets, problems to solve, projects to complete, Web quests, essays to write, and various other kinds of tasks. I would expect that the nature of the homework makes a big difference in the effectiveness of learning and in attitude about school.

All forms of homework can help memory formation. Rehearsal of learned material soon after it is learned is a key to efficient memory formation. In my opinion, failure of a teacher to assign homework is educational malpractice.

Unreliable Memory

It is one thing to forget. It is quite another to remember, but remember wrongly. Everyday experience reveals how commonly people remember things wrongly. Discuss with most anybody what each party said in a past argument or controversy, and it typically happens that people remember things differently. Somebody has to have it wrong. Such "false memories" commonly contaminate eye-witness reports of accidents and crimes.

This possibility came up in a recent a court case in Massachusetts, where a Catholic priest was convicted of sexual molestation of a child. The accuser, now an adult, ostensibly had suppressed the memories, which surfaced later in psychological counseling. On the basis of this resurrected memory, the priest was convicted and the conviction was upheld on appeal by the Massachusetts' Supreme Court. Scholarly literature supporting the notion that real memories can be suppressed and later retrieved provided the basis for believing the charges against the priest.

However, there is other scholarly literature, apparently not persuasive in this case, that asserts that this is "junk science" and that false memories are common. I concur with the news release's statement: "Experiments have shown that false memories can be created that feel just as valid as real ones and cannot be distinguished from real memories."

Our legal system has not really come to grips with false memory. But there is a growing trend to be skeptical of eye-witness testimony. It is increasingly hard to get a conviction if the only evidence against the accused is a single eye-witness report. Perhaps, in the interests of justice, that is best. There is a whole scholarly literature on false memory, including books, and I reviewed much of this in my memory book.

So, the real issue in court cases like this is that the resurrected memory may or may not be true. If there is no other evidence and it is only one person's word against another, how can you tell what the truth is? The same problem exists when people have differing recollections of something that happened in the past. Somebody got it wrong. Who got it right?


Source: UPI press release, http://www.upi.com/Top_News/US/2010/01/17/Repressed-memory-conviction-upheld/UPI-93911263709673/

Learning Versus Memory

Versus? Learning and memory are different, but like two sides of the same coin. What is the difference? Learning is the acquiring of new information or skills. Memory is the remembering of what was learned. You can’t have memory without learning. You can, of course, have learning that you forget.

Learning involves at least four major processes. It all begins with registering new information. This is the stage when information is detected and encoded in brain. Paying attention obviously facilitates the registration process. Multi-tasking can create an information overload in which much of the information never gets registered. Example: a car driver who is all wrapped up in a cell phone conversation may not realize she just ran a stop sign or cut off the driver behind her in the next lane. Another example comes with reading. Reading comprehension (learning) depends heavily on the eyes actually seeing each cluster of words. The reader needs to focus on words, not letters, and needs to think about what the words mean. Likewise in images, what you learn from an image depends on the details in it that you actually notice and think about.

Next is integration. The brain likes to classify, categorize, and organize its information. Thus, new information has to be fitted into existing learned schema. This is the stage where associations are made with existing memory. Brains are really good at detecting and constructing relationships. If a given relationship is not immediately obvious, the brain may figure it out and remember it. Constructing such relationships is an integral part of the learning process.

Associations can be constructed subconsciously. If two things happen at the same time or go together in some other way, even the simplest of brains can learn the association. Moreover, cueing of relationships can produce what is called conditioned learning. We all have heard about Pavlov’s dogs. But even animals as primitive as flatworms can exhibit conditioned learning. If worms are shown flashes of light, not much happens. If they are given mild electrical shocks to the body, the body contracts. If then a flash of light is delivered just prior to an electrical shock, after enough repetitions, the worm starts contracting when it first detects the light, before any electrical shock is delivered.

Associations are still more powerful when they are consciously constructed. This is the stage where you ask yourself such questions as: Where does this information fit with what I already know? How does this relate to other things I could learn about? What value do I place on this information? How invested in using or remembering it should I be?

Then there is understanding. You can, as I did, pass college calculus by using the right formulas for given problem types, and yet not really understand what is going on with the equations. To understand, you need to answer such questions as: Is this consistent with what I thought I knew? What is missing or still confusing? What can I do with this information? What else does it appoly to, how can it be extended? What is predictable?

Learning is not complete without understanding. Understanding also creates a basis for generate insights and creative syntheses, and these in turn advance the depth and rigor of the original learning. Insights typically come from deduction or induction. Deduction is the Sherlock Holmes process of using one fact or observation to lead logically to another. Induction is the Charles Darwin process of using multiple, apparently unrelated, facts or observations to make a synthesis that accommodates them all.

Finally, there is learning to learn. This is the process of learning the paradigm, the “rules of the game,” that allows you to transfer one learned capability to new learning situations that are related. At this point, one has reached a threshold where the more you know, the more you can know.

One of the first experimental demonstrations of this phenomenon was by H. C. Blodgett in 1929. He studied maze behavior in rats, scoring how many errors they made in running the maze to find the location where a food reward was placed. Rats ran the maze once per day on successive days. The control group ran the maze and found the food, with number of errors decreasing slowly on successive days as they learned where in the maze the food was. Experimental groups ran the maze daily for three or seven days without any food reward. Naturally, they made many errors because there was nothing to learn. However, when they subsequently were allowed access to a food reward, the number of errors dropped precipitously on the very next day’s trial. In other words, the rats had been learning about the maze, its layout, number of turns, etc. during the initial explorations when no reward was available.
Blodgett called this “latent learning,” an idea expanded and formalized some 20 years later in the “Learning Set” theory of Harry Harlow. Harlow studied visual discrimination learning in monkeys and observed that visual and other types of discrimination problems progressed more quickly as a function of training on a series of different, but related problems.

These discoveries were born of necessity, arising from the need to use the same monkeys over and over in a wide variety of experiments because the Harlow lab was so under-funded. Increasing the number of problems on which monkeys were tested led to the observation that the monkeys’ general learning competence improved over time. This of course parallels the general common experience of maturation of children.

Harlow developed the prominent theory that learning any task is associated with implicit learning capabilities that can generalize to other related learning situations. The concept relates simpler trial-and-error learning to more advanced insightful-like learning, which he regarded as a mental ability that depended heavily on prior learning sets. Ability to form learning sets varies with species. Monkeys do it better than dogs or cats, and humans do it best of all.The reasons for human superiority in learning no doubt include the rich connections among various brain areas that can support and integrate more learned associations.

"Catch Them Doing Something Right"

Savvy teachers use an operant conditioning technique known as “catch them doing something right.” It works for training seals and pony-and-dog shows in circuses-—why not kids? Well, it does work for kids. The idea is for the teacher to be more aware of what students do, and when students accidentally show some extra effort or accomplishment, they are immediately rewarded in some way. I don’t mean to trivialize the process, but it is not unlike when you are trying to house-break a puppy: when enough time has elapsed that urination is imminent, you take the pup outside. When it urinates, you pat him on the head and say “good dog.” After several such repetitions, the pup learns that the place to urinate is outdoors.

In a school environment, “doing something right” might be when a kid does a little extra on an assignment, or suddenly figures out a problem without prompting, or goes out of her way to make a useful comment in class discussion, etc.

How could this work for an individual? How can you catch yourself doing something right that you want to learn to repeat? First, be more aware of what you are doing. Self-awareness requires also introspection, so that you not only know what you are doing, but think about what is good for you and what attitudes and behaviors you want to develop (i.e., learn). The trick is to find ways to reward yourself when you accidentally do something new that is worth learning on a permanent basis.

For example, suppose you are trying to break a bad habit. You could note how long you can go without doing the habit. Then reward yourself. Using the idea I have described in my book about successive approximations, gradually raise the stakes so that you must go a little longer without a reward. The same idea applies to learning a new habit. When you do the thing you want, like smile more, or spend more time studying, or whatever--reward yourself. Then up the ante before reward.


Rewards can be most anything that pleases you. That is one of the best parts of this method. You get to pick your own reward. Maybe it is “time off for good behavior.” Maybe, you accept some indulgence, like cooking yourself a special meal, or taking yourself to the movies or a ballgame. For small successive approximation rewards, you might give yourself a small piece of candy, or some other treat. You can even create yourself a little “gold star” chart, like adults use with little kids, where you can see your progress in a very obvious way. After so many gold stars, you can give yourself a real treat. Silly? Yes, but it can work.

Sleep Learning -- A New Perspective

A couple of decades ago, many people thought you could learn while you sleep. I remember as a college student playing audio tapes of information I wanted to learn while I slept. This idea turned out to be a fraud, perpetrated by people who sold sleep learning materials and equipment. Most "early adopters" found that all it did was disrupt sleep.

But as I have discussed elsewhere, modern research has compellingly shown that the brain is consolidating memories of the day's events during sleep. So, maybe the sleep learning idea is not completely dead. Maybe the right kind of stimulus input while you sleep could promote learning, at least in terms of promoting memory consolidation of the information you already learned during the day.

So, the idea would be to see if sleep can promote memory consolidation of things you recently learned, but have not yet formed into lasting memory. How might you do that? Since memory is largely associative, maybe it would work to provide during sleep the cues that were associated with the original learning. This might have a better chance of working during the dream stage of sleep, because it is well documented that external sound stimuli (like storms, rain, etc.) are documented as capable of becoming incorporated into and changing the course of a dream. Thus, the question becomes: can audio presentation of learned association cues during dreaming promote the memory formation for the original learning items or events. The idea is that the cue might reactivate a latent memory and thus constitute a memory rehearsal.

Partial testing of this idea has recently been reported. Northwestern University scientists trained human subjects to recognize the location of 50 different objects on a computer screen. Each object had an associated sound. For example, the cat image was associated with a meow sound, a kettle with a whistle, etc. Then people took a nap, during which sound cues were presented (unobstrusively at 62 decibels) for half of the images they had previously been exposed to. After the nap, subjects had no conscious recollection of the sound cueing.

The cues were presented oddly enough only during the deep stages of sleep, not during dreaming. Maybe the researchers were unaware that external stimuli can get incorporated into dreams. Even so, the original objects were re-presented after waking and subjects tested for recall of the location of the 50 images.

Measuring the location errors in terms of distance from correct position indicated that accuracy was greater for images that had associative cues presented during the nap than for those images for which cues were not re-presented. Simultaneous recording of brain waves (EEG) showed that the brain was responding to the sensory cues during sleep.

Tests in control subjects, who were tested without the intervening nap, showed that the cues provided no improvement in recall.

The principle seems sound. What remains is for clever entrepreneurs to develop memory-enhancing strategies that are specific for specific learning tasks.

The old ideas of sleep learning are dead, but here is a new opportunity for finding ways to get sleep to work for us. Learning protocols have to be developed for specific learning tasks, and these have to have relevant sound cues. Finally, I suspect that such external learning "reminders" will be more effective when presented during dream sleep, not the deep stage of sleep in which people "fall into a pit" of oblivion. The challenge is to find ways to provide appropriate reminders while we sleep (or dream).

Source: Rudoy, J. D. et al. 2009. Strengthening individual memories by reactivating them during sleep. Science. 326: 1079.

Kids Can Be Damaged by Excessive Cell-phone Use

As I have explained in my book, almost any activity that is interspersed between learning events, is an interference that can reduce learning efficiency. When children constantly interrupt study (even classroom work) by talking on their cell phones or text messaging, they reduce the efficacy of registering and remembering what they are supposed to learn. This often occurs in an environment of multi-tasking (listening to IPod or MP3 players, playing videogames, blogging, posting on MySpace or Facebook, etc.). These activities create a brain that has a short attention span and difficulty in focusing.

Now comes new scientific evidence that cell phone use may actually change brain chemistry. Some scientists say that cellphone use does have a biological effect on the brain. A recent study at Örebro University in Sweden reported that physical changes occur in brain from the radiation emitted by cell phones. Cellphone use increases the amount of a protein called transthyretin, which is a carrier of thyroid hormones in serum and is part of the ceberospinal fluid that cushions and protects the brain. But the researchers did not comment if the change is good or bad for the brain. But in any case, this should give us pause.

Children are more likely to be affected by cell-phone radiation than adults. Children have much thinner skull bones and their brains have a lot more fluid, so their brain tissues would likely absorb much more radiation compared to an adult’s brain.

The Swedish study found that children and teenagers who were heavy cell phone users were indeed more likely to report health problems. These included headaches and impaired concentration. This impaired concentration may have a biological cause in addition to the poor habits of mind that develop from excessive multi-tasking.

Source: Adapted from materials provided by The Swedish Research Council, via AlphaGalileo.