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Wednesday, March 31, 2010

Inaccurate and Biased Beliefs About Learning and Memory

A very sophisticated and comprehensive set of 12 experiments confirms what experienced teachers have long known: students over-estimate how much they know and under-estimate the value of repeated study of the same material. This bias may apply to everyone, but the study was performed on college students. UCLA researchers studied the reliability of people's ability to judge how well they had remembered something just studied and to predict how well they could remember if they went over the same material in several sessions.

They asked the students to look at a list of word pairs and make two estimates: one a judgement of how well they remembered what they just studied and the other a prediction of how well they would be able to remember the words after subsequent study of those same word lists.

When asked after a given study trial to judge how well they thought they remembered, students' judgment of their knowledge was not confirmed by actual performance on the test.That is, they over-estimated how much they had learned.

Amazingly, students predicted little or no learning improvement would occur with repeated study sessions, yet they actually showed large increases in actual learning with repeated study. The change in predicted performance was about the same, irrespective of whether the word pairs were deemed easy or hard to remember. However, the actual performance benefit of extra study was especially  marked for the hard-to-remember words.

Other studies have shown that people fail to predict accurately how much their memory of specific learning will deteriorate over time after the intiial learning.

Why does this matter? Well, it affects how well one manages learning tasks; that is, choosing the best activities that will create lasting memories, as for example, students choosing how and when to study.  The implication is that students don't study as much as they should because they don't appreciate the value of extra study, especially for hard-to-learn material. They also don't study as much as they need to because they think they have learned more than they really have.

Is the problem that students are generally not as smart as they think they are? Or do they fail to study more because they don't correctly realize how much it would help? The ultimate consequence is that students tend to study too little and give up too quickly.

The authors suggest that these inaccurate beliefs and the negative consequences just reflect normal psychology. They do not consider that mental laziness could be a factor. Nor do they consider that this effect might be age-specific.

This may also relate to an observation that has puzzled me ever since I wrote my original book on memory improvement. Students have not been as interested in what the book had to say as I expected. Nor do they show as much interest as I anticipated in attending my lectures on the subject. At one unversity where I recently gave a well-advertised talk on how to improve memory, not one student showed up -- only faculty. Older adults, in general, seem to realize they need to work on their memory. Students tend to think they are either just fine as they are or can't improve.

A related matter is that students don't appreciate the value of testing in enhancing memory. This value was confirmed in the present study, and I have elsewhere discussed similar findings. Testing forces retrieval of stored information and that retrieval is a strong rehearsal process that reinforces the memory.


Kornell, N. and Bjork, R. A. 2009. A stability bias in human memory: overestimating remembering and underestimating learning. J. Exp. Psychol. 138 (4): 449-468.

Monday, March 15, 2010

Vitamin D and Memory

A general rule regarding memory and nutrients is that most dietary supplements are without effect unless a person has an inadequate diet. One nutrient of special interest is vitamin D. Vitamin D is synthesized in the skin from exposure to sunlight, but many people don't get enough sunlight every day. Sun-tan lotions, designed to reduce the risk of skin cancer, also reduce the likelihood that the skin can make enough vitamin D. Particularly vulnerable populations include Blacks and elderly who are confined indoors. Also the ability of skin to synthesize vitamin D declines with age.

Vitamin D and its receptors are found throughout the body. In recent years, scientists have learned that it contributes to normal cognitive function, including memory. Vitamin D increases the brain neurotransmitter chemical called acetylcholine, which is the most important transmitter for creating conscious arousal and attentiveness. Vitamin D also stimulates synthesis of nerve growth factor, which can promote growth of nerve terminals.

A recent study has confirmed results from another lab suggesting that normal brain function requires vitamin D. Participants, 1,766 adults aged 65 years and older, were evaluated to compare blood levels of vitanim D precursor and cognitive ability. Lower levels occurred in the subset of people who were cognitively impaired, compared to the normal subjects.

Another independent study reports similar findings. The study examined 3,133 men aged 40 to 79 at eight test centers across Europe. Men who had a better memory and were quicker to process information had higher levels of vitamin D. Men with 35 nanomoles per litre or less of vitamin D in their blood performed poorly.

These are only correlational studies, but they do suggest that increasing dietary vitamin D can improve memory in people who are vitamin D deficient. This idea awaits experimental verification. In the meanwhile, taking modest doses of vitamin D (use the D3 version, about 1,000-2,000 I.U. per day) is probably a good idea.


Llewellyn. D. J. 2009. Journal of Geriatric Psychiatry and Neurology, Vol. 22, No. 3, 188-195 OI: 10.1177/0891988708327888

Lee, D. M. et al. 2009. J Neurol Neurosurg Psychiatry 2009;80:722-729 Published Online First: 21 May. doi:10.1136/jnnp.2008.165720

Monday, March 08, 2010

A Handy List of Memory Tips

One of the followers of this blog called my attention to a useful web site that has a list of 100 things you can do to facilitate memory. Several items deal with remembering names, and others with remembering numbers and lists. Much of this information is also in my book.

I have some quibbles with some of the material, such as recommended foods. The hoopla over gingko balboa, for example, has not been replicated by research. Certain other foods are only beneficial if you are nutritionally deficient.

I particularly like the lists of things you can do to organize information, and even store it conveniently (as with sticky notes, Evernote, etc.) so you don't have to memorize everything.

Check it out:

By the way, if you have been following my blog, you will have noticed that it is starting to attract a following. I even get fan mail.

Sunday, March 07, 2010

More Bad News for Multi-tasking

Memory formation is often prevented when one event follows too soon after an initial learning event. It is also true that memory of initial learning events can be blocked if you try to learn two things at once. In fact, learning may be disrupted for both things.

In a recent test of this phenomenon, a group of 29 people (17 to 30 years of age) was trained to discriminate two sound pips that differed in length by a fraction of a second. In one group of subjects, the training occurred consecutively, which ordinarily produces some inefficiency with learning because the second task interferes with remembering the first. In this study, some learning did occur, in spite of the sequential tasks. However, results from another group of subjects revealed that when practice on the two tasks was interleaved, there was no learning on either condition.

This indicates that acquistion (initial learning) is vulnerable to multi-tasking, perhaps even more so than when learning of one task is followed too soon by another learning task. In other words, multi-tasking can interfere with initial learning, just as it does with formation of memory.

Source: Banai, K. et al. 2010. Learning two things at once: differential constraints on the acquisition and consolidation of perceptual learning. Neuroscience. 165: 436-444.