Running faster changes brain rhythms associated with learning

September, 2011

A mouse study finds that gamma waves in the hippocampus, critically involved in learning, grow stronger as mice run faster.

I’ve always felt that better thinking was associated with my brain working ‘in a higher gear’ — literally working at a faster rhythm. So I was particularly intrigued by the findings of a recent mouse study that found that brainwaves associated with learning became stronger as the mice ran faster.

In the study, 12 male mice were implanted with microelectrodes that monitored gamma waves in the hippocampus, then trained to run back and forth on a linear track for a food reward. Gamma waves are thought to help synchronize neural activity in various cognitive functions, including attention, learning, temporal binding, and awareness.

We know that the hippocampus has specialized ‘place cells’ that record where we are and help us navigate. But to navigate the world, to create a map of where things are, we need to also know how fast we are moving. Having the same cells encode both speed and position could be problematic, so researchers set out to find how speed was being encoded. To their surprise and excitement, they found that the strength of the gamma rhythm grew substantially as the mice ran faster.

The results also confirmed recent claims that the gamma rhythm, which oscillates between 30 and 120 times a second, can be divided into slow and fast signals (20-45 Hz vs 45-120 Hz for mice, consistent with the 30-55 Hz vs 45-120 Hz bands found in rats) that originate from separate parts of the brain. The slow gamma waves in the CA1 region of the hippocampus were synchronized with slow gamma waves in CA3, while the fast gamma in CA1 were synchronized with fast gamma waves in the entorhinal cortex.

The two signals became increasingly separated with increasing speed, because the two bands were differentially affected by speed. While the slow waves increased linearly, the fast waves increased logarithmically. This differential effect could have to do with mechanisms in the source regions (CA3 and the medial entorhinal cortex, respectively), or to mechanisms in the different regions in CA1 where the inputs terminate (the waves coming from CA3 and the entorhinal cortex enter CA1 in different places).

In the hippocampus, gamma waves are known to interact with theta waves. Further analysis of the data revealed that the effects of speed on gamma rhythm only occurred within a narrow range of theta phases — but this ‘preferred’ theta phase also changed with running speed, more so for the slow gamma waves than the fast gamma waves (which is not inconsistent with the fact that slow gamma waves are more affected by running speed than fast gamma waves). Thus, while slow and fast gamma rhythms preferred similar phases of theta at low speeds, the two rhythms became increasingly phase-separated with increasing running speed.

What’s all this mean? Previous research has shown that if inputs from CA3 and the entorhinal cortex enter CA1 at the same time, the kind of long-term changes at the synapses that bring about learning are stronger and more likely in CA1. So at low speeds, synchronous inputs from CA3 and the entorhinal cortex at similar theta phases make them more effective at activating CA1 and inducing learning. But the faster you move, the more quickly you need to process information. The stronger gamma waves may help you do that. Moreover, the theta phase separation of slow and fast gamma that increases with running speed means that activity in CA3 (slow gamma source) increasingly anticipates activity in the medial entorhinal cortex (fast gamma source).

What does this mean at the practical level? Well at this point it can only be speculation that moving / exercising can affect learning and attention, but I personally am taking this on board. Most of us think better when we walk. This suggests that if you’re having trouble focusing and don’t have time for that, maybe walking down the hall or even jogging on the spot will help bring your brain cells into order!

Pushing speculation even further, I note that meditation by expert meditators has been associated with changes in gamma and theta rhythms. And in an intriguing comparison of the effect of spoken versus sung presentation on learning and remembering word lists, the group that sang showed greater coherence in both gamma and theta rhythms (in the frontal lobes, admittedly, but they weren’t looking elsewhere).

So, while we’re a long way from pinning any of this down, it may be that all of these — movement, meditation, music — can be useful in synchronizing your brain rhythms in a way that helps attention and learning. This exciting discovery will hopefully be the start of an exploration of these possibilities.



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Preventing interference between topics or skills

September, 2011

Learning two tasks or subjects one after another typically leads to poorer remembering of the first. A new study indicates the cause and suggests a remedy.

Trying to learn two different things one after another is challenging. Almost always some of the information from the first topic or task gets lost. Why does this happen? A new study suggests the problem occurs when the two information-sets interact, and demonstrates that disrupting that interaction prevents interference. (The study is a little complicated, but bear with me, or skip to the bottom for my conclusions.)

In the study, young adults learned two memory tasks back-to-back: a list of words, and a finger-tapping motor skills task. Immediately afterwards, they received either sham stimulation or real transcranial magnetic stimulation to the dorsolateral prefrontal cortex or the primary motor cortex. Twelve hours later the same day, they were re-tested.

As expected from previous research, word recall (being the first-learned task) declined in the control condition (sham stimulation), and this decline correlated with initial skill in the motor task. That is, the better they were at the second task, the more they forgot from the first task. This same pattern occurred among those whose motor cortex had been stimulated. However, there was no significant decrease in word recall for those who had received TMS to the dorsolateral prefrontal cortex.

Learning of the motor skill didn't differ between the three groups, indicating that this effect wasn't due to a disruption of the second task. Rather, it seems that the two tasks were interacting, and TMS to the DLPFC disrupted that interaction. This hypothesis was supported when the motor learning task was replaced by a motor performance task, which shouldn’t interfere with the word-learning task (the motor performance task was almost identical to the motor learning task except that it didn’t have a repeating sequence that could be learned). In this situation, TMS to the DLPFC produced a decrease in word recall (as it did in the other conditions, and as it would after a word-learning task without any other task following).

In the second set of experiments, the order of the motor and word tasks was reversed. Similar results occurred, with this time stimulation to the motor cortex being the effective intervention. In this case, there was a significant increase in motor skill on re-testing — which is what normally happens when a motor skill is learned on its own, without interference from another task (see my blog post on Mempowered for more on this). The word-learning task was then replaced with a vowel-counting task, which produced a non-significant trend toward a decrease in motor skill learning when TMS was applied to the motor cortex.

The effect of TMS depends on the activity in the region at the time of application. In this case, TMS was applied to the primary motor cortex and the DLPFC in the right hemisphere, because the right hemisphere is thought to be involved in integrating different types of information. The timing of the stimulation was critical: not during learning, and long before testing. The timing was designed to maximize any effects on interference between the two tasks.

The effect in this case mimics that of sleep — sleeping between tasks reduces interference between them. It’s suggested that both TMS and sleep reduce interference by reducing the communication between the prefrontal cortex and the mediotemporal lobe (of which the hippocampus is a part).

Here’s the problem: we're consolidating one set of memories while encoding another. So, we can do both at the same time, but as with any multitasking, one task is going to be done better than the other. Unsurprisingly, encoding appears to have priority over consolidation.

So something needs to regulate the activity of these two concurrent processes. Maybe something looks for commonalities between two actions occurring at the same time — this is, after all, what we’re programmed to do: we link things that occur together in space and time. So why shouldn’t that occur at this level too? Something’s just happened, and now something else is happening, and chances are they’re connected. So something in our brain works on that.

If the two events/sets of information are connected, that’s a good thing. If they’re not, we get interference, and loss of data.

So when we apply TMS to the prefrontal cortex, that integrating processor is perhaps disrupted.

The situation may be a little different where the motor task is followed by the word-list, because motor skill consolidation (during wakefulness at least) may not depend on the hippocampus (although declarative encoding does). However, the primary motor cortex may act as a bridge between motor skills and declarative memories (think of how we gesture when we explain something), and so it may this region that provides a place where the two types of information can interact (and thus interfere with each other).

In other words, the important thing appears to be whether consolidation of the first task occurs in a region where the two sets of information can interact. If it does, and assuming you don’t want the two information-sets to interact, then you want to disrupt that interaction.

Applying TMS is not, of course, a practical strategy for most of us! But the findings do suggest an approach to reducing interference. Sleep is one way, and even brief 20-minute naps have been shown to help learning. An intriguing speculation (I just throw this out) is that meditation might act similarly (rather like a sorbet between courses, clearing the palate).

Failing a way to disrupt the interaction, you might take this as a warning that it’s best to give your brain time to consolidate one lot of information before embarking on an unrelated set — even if it's in what appears to be a completely unrelated domain. This is particularly so as we get older, because consolidation appears to take longer as we age. For children, on the other hand, this is not such a worry. (See my blog post on Mempowered for more on this.)


[2338] Cohen DA, Robertson EM. Preventing interference between different memory tasks. Nat Neurosci [Internet]. 2011 ;14(8):953 - 955. Available from:


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Learning another language

Older news items (pre-2010) brought over from the old website

Literate Arabic speakers have bilingual brains

Research has found that Arabic-speaking students tend to be less proficient in reading than other students are in their native language. Spoken Arabic comes in a variety of dialects and is quite different from the common written Arabic (Modern Standard Arabic - MSA). A new imaging study has now compared brain activity in a priming task among trilinguals fluent in MSA, spoken Arabic and Hebrew. The results revealed that the cognitive process in using MSA was more similar to that employed for Hebrew, and less similar to the cognitive process of using the spoken native language. These results not only help explain why learning to read is more difficult for Arabic speakers, but also suggests that the most effective way of teaching written Arabic is by using techniques usually employed for the instruction of a second language — including exposing children to written Arabic in preschool or kindergarten.

Ibrahim, R. 2009. The cognitive basis of diglossia in Arabic: Evidence from a repetition priming study within and between languages. Journal of Psychology Research and Behavior Management, 2.

Relearning a forgotten language is easier for those under 40

A small study involving 7 native English speakers who had learned either Hindi or Zulu as children when living abroad, but now had no memory of the neglected language, found that the three who were under 40 could relearn certain phonemes that are difficult for native English speakers to recognize, but those over 40, like those who had never been exposed to the language in childhood, could not. The amount of experience of exposure in childhood ranged from 4 to 10 years, and it’s especially notable that the 47-year old individual who had 10 years exposure, having become almost fluent, still could not recover the ability to distinguish these difficult sounds. It should also be noted that where the ability was recovered (and recovered almost to native ability), it took about 15-20 training sessions. The findings point to the value of early foreign language learning.

[975] Bowers JS, Mattys SL, Gage SH. Preserved implicit knowledge of a forgotten childhood language. Psychological Science: A Journal of the American Psychological Society / APS [Internet]. 2009 ;20(9):1064 - 1069. Available from:

Exposure to two languages carries far-reaching benefits

A new study provides evidence that bilingual speakers find it easier to learn a new language than those who only know one language. The study compared the ability of three groups of native English speakers - English-Mandarin bilinguals, English-Spanish bilinguals and monolinguals - to master words in an invented language that bore no relationship to English, Spanish or Mandarin. The bilingual participants mastered nearly twice the number of words as the monolinguals. The finding adds more support to the value of introducing another language to children at a young age.

[235] Kaushanskaya M, Marian V. The bilingual advantage in novel word learning. Psychonomic Bulletin & Review [Internet]. 2009 ;16(4):705 - 710. Available from:

Bilingual babies get a head start on executive functioning

A number of studies have pointed to benefits of being bilingual, but many people still believe that the experience of two languages in infancy may cause confusion and impair their acquisition of language. Now a new study shows that bilingual babies quickly adapt to different learning cues at seven months old compared with babies from single-language households. The study involved families in the Trieste area of Italy, where parents spoke to infants from birth using both Italian and Slovenian mother tongues. When bilingual and monolingual babies were first taught to look at one side of a screen in response to a sound cue (and in anticipation of a visual "reward" image of a puppet), then required to switch sides, it was found that bilingual babies quickly learned to look at the other side, but the monolingual babies never adapted to the change. The findings indicate that bilingualism gives an advantage above the purely linguistic, in executive function, which is consistent with other research indicating bilingual children have improved attention.

[1110] Kovacs AM, Mehler J. Cognitive gains in 7-month-old bilingual infants. Proceedings of the National Academy of Sciences [Internet]. 2009 ;106(16):6556 - 6560. Available from:

Anatomical advantage for second language learners

Based on the size of a small brain region called Heschl's Gyrus (HG) in the left hemisphere, researchers found they could predict who would be more successful in learning 18 words in an invented language (those predicted to be "more successful learners" achieved an average of 97% accuracy in identifying the pseudo words, compared to 63% from those deemed "less successful"). The size of the right HG was not important. The finding was surprising, given that this area, the primary region of the auditory cortex, is typically associated with handling the basic building blocks of sound — whether the pitch of a sound is going up or down, where sounds come from, and how loud a sound is — rather than speech per se.

[1147] Wong PCM, Warrier CM, Penhune VB, Roy AK, Sadehh A, Parrish TB, Zatorre RJ. Volume of Left Heschl's Gyrus and Linguistic Pitch Learning. Cereb. Cortex [Internet]. 2008 ;18(4):828 - 836. Available from:

Early music training 'tunes' auditory system

Mandarin is a tonal language, that is, the pitch pattern is as important as the sound of the syllables in determining the meaning of a word. In a small study, a Mandarin word was presented to 20 adults as they watched a movie. All were native English speakers with no knowledge of Mandarin, but half had at least six years of musical instrument training starting before the age of 12, while half had minimal or no musical training. As the subjects watched the movie, the researchers measured the accuracy of their brainstem ability to track three differently pitched "mi" sounds. Those who were musically trained were far better at tracking the three different tones than the non-musicians. The study is the first to provide concrete evidence that playing a musical instrument significantly enhances the brainstem's sensitivity to speech sounds, and supports the view that experience with music at a young age can "fine-tune" the brain's auditory system. The findings are in line with previous studies suggesting that musical experience can improve one's ability to learn tone languages in adulthood, and are also consistent with studies revealing anomalies in brainstem sound encoding in some children with learning disabilities which can be improved by auditory training. The findings are also noteworthy for implicating the brainstem in processing that has been thought of as exclusively involving the cortex.

[667] Wong PCM, Skoe E, Russo NM, Dees T, Kraus N. Musical experience shapes human brainstem encoding of linguistic pitch patterns. Nat Neurosci [Internet]. 2007 ;10(4):420 - 422. Available from:

Why learning a new language may make you forget your old one

The common experience of having difficulty remembering words in your native language when you’ve been immersed in a new language is called first-language attrition, and new research has revealed that it occurs because native language words that might distract us when we are mastering a new language are actively inhibited. The study also found that this inhibition lessened as students became more fluent with the new language, suggesting it principally occurs during the initial stages of second language learning.

[659] Levy BJ, McVeigh ND, Marful A, Anderson MC. Inhibiting your native language: the role of retrieval-induced forgetting during second-language acquisition. Psychological Science: A Journal of the American Psychological Society / APS [Internet]. 2007 ;18(1):29 - 34. Available from:

Bilingualism has protective effect in delaying onset of dementia

An analysis of 184 people with dementia (132 were diagnosed with Alzheimer’s; the remaining 52 with other dementias) found that the mean age of onset of dementia symptoms in the 91 monolingual patients was 71.4 years, while for the 93 bilingual patients it was 75.5 years — a very significant difference. This difference remained even after considering the possible effect of cultural differences, immigration, formal education, employment and even gender as influencers in the results.

[1271] Bialystok E, Craik FIM, Freedman M. Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia [Internet]. 2007 ;45(2):459 - 464. Available from:

How bilingualism affects the brain

Using a new technique, researchers have shed light on how bilingualism affects the brain. The study involved 20 younger adults of whom half were bilingual in Spanish and English. Similar brain activity, in the left Broca's area and left dorsolateral prefrontal cortex (DLPFC), was found in bilinguals and monolinguals when the task involved only one language. However, when the bilinguals were simultaneously processing each of their two languages and rapidly switching between them, they showed an increase in brain activity in both the left and the right hemisphere Broca's area, with greater activation in the right equivalent of Broca's area and the right DLPFC. The findings support the view that the brains of bilinguals and monolinguals are similar, and both process their individual languages in fundamentally similar ways, but bilinguals engage more of the neurons available for language processing.

The study was presented at the Society for Neuroscience's annual meeting on October 14-18 in Atlanta, Ga.

How does the bilingual brain distinguish between languages?

Studies of bilingual people have found that the same brain regions, particularly parts of the left temporal cortex, are similarly activated by both languages. But there must be some part of the brain that knows one language from another. A new imaging study reveals that this region is the left caudate — a finding supported by case studies of bilingual patients with damage to the left caudate, who are prone to switch languages involuntarily.

[405] Stockton K, Usui K, Green DW, Price CJ, Crinion J, Turner R, Grogan A, Hanakawa T, Noppeney U, Devlin JT, et al. Language Control in the Bilingual Brain. Science [Internet]. 2006 ;312(5779):1537 - 1540. Available from:

Fast language learners have more white matter in auditory region

An imaging study has found that fast language learners have more white matter in a region of the brain that’s critical for processing sound. The study involved 65 French adults in their twenties, who were asked to distinguish two closely related sounds (the French 'da' sound from the Hindi 'da' sound). There was considerable variation in people’s ability to learn to tell these sounds apart — the fastest could do it within 8 minutes; the slowest were still guessing randomly after 20 minutes. The 11 fastest and 10 slowest learners were then given brain scans, revealing that the fastest learners had, on average, 70% more white matter in the left Heschl's gyrus than the slowest learners, as well as a greater asymmetry in the parietal lobe (the left being bigger than the right).

[569] Golestani N, Molko N, Dehaene S, LeBihan D, Pallier C. Brain Structure Predicts the Learning of Foreign Speech Sounds. Cereb. Cortex [Internet]. 2007 ;17(3):575 - 582. Available from:

Language learning declines after second year of life

A study involving 96 deaf children who had received cochlear implants during their first four years of life has found that the rate of language learning was greatest for those given implants before they turned two. Children given implants at three or four years of age acquired language skills more slowly. The finding supports the idea that there is a 'sensitive period' for language learning, and suggests that deaf children should get cochlear implants sooner (it is still relatively rare for them to be given to children younger than two).

The findings were presented on 16 May at the Acoustical Society of America conference in Vancouver, Canada.

Learning languages increases gray matter density

An imaging study of 25 Britons who did not speak a second language, 25 people who had learned another European language before the age of five and 33 bilinguals who had learned a second language between 10 and 15 years old found that the density of the gray matter in the left inferior parietal cortex of the brain was greater in bilinguals than in those without a second language. The effect was particularly noticeable in the "early" bilinguals. The findings were replicated in a study of 22 native Italian speakers who had learned English as a second language between the ages of two and 34.

Mechelli, A., Crinion, J.T., Noppeney, U., O'doherty, J., Ashburner, J., Frackowiak, R.S. & Price, C.J. 2004. Neurolinguistics: Structural plasticity in the bilingual brain. Nature, 431, 757.

Being fluent in two languages may help keep the brain sharper for longer

A study of 104 people aged between 30 and 88 has found that those who were fluent in two languages rather than just one were sharper mentally. Those fluent in two languages responded faster on tasks assumed to place demands on working memory, compared to those who were fluent in just English, at all age groups. This is consistent with the theory that constant management of 2 competing languages enhances executive functions. Bilingual volunteers were also much less likely to suffer from the mental decline associated with old age. The finding is consistent with other research suggesting that mental activity helps in protecting older adults from mental decline. The participants were all middle class, and educated to degree level. Half of the volunteers came from Canada and spoke only English. The other half came from India and were fluent in both English and Tamil.

[268] Bialystok E, Craik FIM, Klein R, Viswanathan M. Bilingualism, aging, and cognitive control: evidence from the Simon task. Psychology and Aging [Internet]. 2004 ;19(2):290 - 303. Available from:

Learning a second language may not be as laborious as believed

A study of adult learners of a second language has revealed that their brains still possess a surprising facility for learning words — much greater than the learner is consciously aware of. College students learning first-year French demonstrated brain activity that was clearly discriminating between real and pseudo-French words after only 14 hours of classroom instruction, although the students performed only at chance levels when asked to consciously choose whether or not the stimuli were real French words. The greater the exposure to French, the larger the difference in brain response to words and pseudo words.

[428] McLaughlin J, Osterhout L, Kim A. Neural correlates of second-language word learning: minimal instruction produces rapid change. Nature Neuroscience [Internet]. 2004 ;7(7):703 - 704. Available from:

Beneficial effects of bilingual learning

A recent Canadian study comparing young monolingual children to bilingual found that bilingual children were much better at a non-language cognitive task. The 4-6 year old bilingual children were versed in a spoken language and a signing one. It was suggested that their higher cognitive skill was due to the increased computational demands of processing two different language systems.

Baker, S.A., Kovelman, I., Bialystok, E. & Petitto, L. A. (2003, November). “Bilingual children’s complex linguistic experience yields a cognitive advantage.” Presented at 2003 Society For Neuroscience conference. New Orleans, LA.

Both languages active in bilingual speakers

An imaging study involving bilingual Dutch and English speakers suggests that when a bilingual person is speaking a second language, the first language is always active and cannot be suppressed. It was thought that an environment of total immersion in a language would provide massive exposure to a second language and suppress the first language. However, it’s now suggested that a large component of language immersion involves learning a new set of cues to the second language. To test this, students with no exposure to German or Dutch were taught 40 Dutch words. Some students learned the words in association with their English counterparts and others learned the words in association with a picture. Some of the pictures were oriented in the normal way and others were upside down or otherwise skewed. People who learned the Dutch in association with an object that was oriented uniquely were faster to later translate English words into Dutch. The mis-oriented pictures served as a unique cue.

The research was presented at the Second Language Research Forum, October 18, in Tucson, Arizona.

Second language best taught in childhood

Sadly, it does appear that the easiest time to learn a second language is, indeed, in childhood. An imaging study has found that when grammatical judgement in the second language was compared to grammatical judgement in first language (as evidenced by performance on sentences with grammatical mistakes), there was no difference in brain activation in those who learned the second language as children. However, people who acquired the second language late and with different proficiency levels displayed significantly more activity in the Broca's region during second language grammatical processing. "This finding suggests that at the level of brain activity, the parallel learning of the two languages since birth or the early acquisition of a second language are crucial in the setting of the neural substrate for grammar."

[232] Wartenburger I, Heekeren HR, Abutalebi J, Cappa SF, Villringer A, Perani D. Early Setting of Grammatical Processing in the Bilingual Brain. Neuron [Internet]. 2003 ;37(1):159 - 170. Available from:

Study finds there's a critical time for learning all languages, including sign language

It is generally believed that there is a critical period for learning a first language, and that children not exposed to language during this period will never fully acquire language. It is also thought that this might apply as well to second language learning — that those who learn another language after puberty can never become as fluent as those who learn it before puberty. A recent study suggests that this may also be true for non-verbal languages. Using functional magnetic resonance imaging (fMRI), it was found that patterns of brain activity in bilingual people who learned American Sign Language (ASL) before puberty differed from those who learned it after puberty.

[1431] Newman AJ, Bavelier D, Corina D, Jezzard P, Neville HJ. A critical period for right hemisphere recruitment in American Sign Language processing. Nat Neurosci [Internet]. 2002 ;5(1):76 - 80. Available from:

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Testing to learn: Best practice

September, 2011

Two studies reaffirm the value of retrieval practice, and suggest how often you need to retrieve each item.

In the first study, undergraduates studied English-Lithuanian word pairs, which were displayed on a screen one by one for 10 seconds. After studying the list, the students practiced retrieving the English words — they had 8 seconds to type in the English word as each Lithuanian word appeared, and those that were correct went to the end of the list to be asked again, and those wrong had to be restudied. Each item was pre-assigned a "criterion level" from one to five — the number of times it needed to be correctly recalled during practice.

In the first experiment, participants took one of four recall tests and one of three recognition tests after a 2-day delay. In the second experiment, in order to eliminate the reminder effect of the recall test, participants were only given a recognition test, after a 1-week delay.

Both experiments found that higher criterion levels led to better memory. More importantly, through the variety of tests, they showed that this occurred on all three kinds of memory tested: associative memory; target memory; cue memory. That is, practicing retrieval of the English word didn’t just improve memory for that word (the target), but also for the Lithuanian word (the cue), and the pairing (association).

While this may seem self-evident to some, it has been thought that only the information being retrieved is strengthened by retrieval practice. The results also emphasize that it is the correct retrieval of the information that improves memory, not the number of times the information is studied.

In a related study, 533 students learned conceptual material via retrieval practice across three experiments. Criterion levels varied from one to four correct retrievals in the initial session. Items also varied in how many subsequent sessions they were exposed to. In one to five testing/relearning sessions, the items were practiced until they were correctly recalled once. Memory was tested one to four months later.

It was found that the number of times items were correctly retrieved on the initial session had a strong initial effect, but this weakened as relearning increased. Relearning had pronounced effects on long-term retention with a relatively minimal cost in terms of additional practice trials.

On the basis of their findings, the researchers recommend that students practice recalling concepts to an initial criterion of three correct recalls and then relearn them three times at widely spaced intervals.


[2457] Vaughn KE, Rawson KA. Diagnosing Criterion-Level Effects on Memory. Psychological Science [Internet]. 2011 . Available from:

Rawson, K.A. & Dunlosky, J. 2011. Optimizing schedules of retrieval practice for durable and efficient learning: How much is enough? Journal of Experimental Psychology: General, Jun 27, 2011, No Pagination Specified. doi: 10.1037/a0023956


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Why spaced practice is better

September, 2011

New mouse research helps explain why the spacing effect occurs.

I’ve spoken often about the spacing effect — that it’s better to spread out your learning than have it all massed in a block. A study in which mice were trained on an eye movement task (the task allowed precise measurement of learning in the brain) compared learning durability after massed training or training spread over various spaced intervals (2.5 hours to 8 days, with 30 minute to one day intervals). In the case of massed training, the learning achieved at the end of training disappeared within 24 hours. However learning gained in spaced training did not.

Moreover, when a region in the cerebellum connected to motor nuclei involved in eye movement (the flocculus) was anesthetized, the learning achieved from one hour of massed training was eliminated, while learning achieved from an hour of training spaced out over four hours was unaffected. This suggests that the memories had been transferred out of the flocculus (to the vestibular nuclei) within four hours.

However, when protein synthesis in the flocculus was blocked, learning from spaced training was impaired, while learning from massed training was not. This suggests that proteins synthesized in the flocculus play a vital part in the transfer to the vestibular nuclei.



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Theta brainwaves improve remembering

September, 2011

New research suggests that successful retrieval depends not only on retrieval cues, but also on your preceding brain state.

What governs whether or not you’ll retrieve a memory? I’ve talked about the importance of retrieval cues, of the match between the cue and the memory code you’re trying to retrieve, of the strength of the connections leading to the code. But these all have to do with the memory code.

Theta brainwaves, in the hippocampus especially, have been shown to be particularly important in memory function. It has been suggested that theta waves before an item is presented for processing lead to better encoding. Now a new study reveals that, when volunteers had to memorize words with a related context, they were better at later remembering the context of the word if high theta waves were evident in their brains immediately before being prompted to remember the item.

In the study, 17 students made pleasantness or animacy judgments about a series of words. Shortly afterwards, they were presented with both new and studied words, and asked to indicate whether the word was old or new, and if old, whether the word had been encountered in the context of “pleasant” or “alive”. Each trial began with a 1000 ms presentation of a simple mark for the student to focus on. Theta activity during this fixation period correlated with successful retrieval of the episodic memory relating to that item, and larger theta waves were associated with better source memory accuracy (memory for the context).

Theta activity has not been found to be particularly associated with greater attention (the reverse, if anything). It seems more likely that theta activity reflects a state of mind that is oriented toward evaluating retrieval cues (“retrieval mode”), or that it reflects reinstatement of the contextual state employed during study.

The researchers are currently investigating whether you can deliberately put your brain into a better state for memory recall.


[2333] Addante RJ, Watrous AJ, Yonelinas AP, Ekstrom AD, Ranganath C. Prestimulus theta activity predicts correct source memory retrieval. Proceedings of the National Academy of Sciences [Internet]. 2011 ;108(26):10702 - 10707. Available from:



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Negative emotion can enhance memory for tested information

September, 2011

Images designed to arouse strong negative emotion can improve your memory for information you’re learning, if presented immediately after you’ve been tested on it.

In a recent study, 40 undergraduate students learned ten lists of ten pairs of Swahili-English words, with tests after each set of ten. On these tests, each correct answer was followed by an image, either a neutral one or one designed to arouse negative emotions, or by a blank screen. They then did a one-minute multiplication test before moving on to the next section.

On the final test of all 100 Swahili-English pairs, participants did best on items that had been followed by the negative pictures.

In a follow-up experiment, students were shown the images two seconds after successful retrieval. The results were the same.

In the final experiment, the section tests were replaced by a restudying period, where each presentation of a pair was followed by an image or blank screen. The effect did not occur, demonstrating that the effect depends on retrieval.

The study focused on negative emotion because earlier research has found no such memory benefit for positive images (including images designed to be sexually arousing).

The findings emphasize the importance of the immediate period after retrieval, suggesting that this is a fruitful time for manipulations that enhance or impair memory. This is consistent with the idea of reconsolidation — that when information is retrieved from memory, it is in a labile state, able to be changed. Thus, by presenting a negative image when the retrieved memory is still in that state, the memory absorbs some of that new context.


[2340] Finn B, Roediger HL. Enhancing Retention Through Reconsolidation. Psychological Science [Internet]. 2011 ;22(6):781 - 786. Available from:


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The effect of stress on performance depends on individual and situational factors

September, 2011

A new study shows how stress only impacts math performance in those with both higher working memory capacity and math anxiety, while another shows that whether or not pressure impacts your performance depends on the nature of the pressure and the type of task.

Working memory capacity and level of math anxiety were assessed in 73 undergraduate students, and their level of salivary cortisol was measured both before and after they took a stressful math test.

For those students with low working memory capacity, neither cortisol levels nor math anxiety made much difference to their performance on the test. However, for those with higher WMC, the interaction of cortisol level and math anxiety was critical. For those unafraid of math, the more their cortisol increased during the test, the better they performed; but for those anxious about math, rising cortisol meant poorer performance.

It’s assumed that low-WMC individuals were less affected because their performance is lower to start with (this shouldn’t be taken as an inevitability! Low-WMC students are disadvantaged in a domain like math, but they can learn strategies that compensate for that problem). But the effect on high-WMC students demonstrates how our attitude and beliefs interact with the effects of stress. We may all have the same physiological responses, but we interpret them in different ways, and this interpretation is crucial when it comes to ‘higher-order’ cognitive functions.

Another study investigated two theories as why people choke under pressure: (a) they’re distracted by worries about the situation, which clog up their working memory; (b) the stress makes them pay too much attention to their performance and become self-conscious. Both theories have research backing from different domains — clearly the former theory applies more to the academic testing environment, and the latter to situations involving procedural skill, where explicit attention to the process can disrupt motor sequences that are largely automatic.

But it’s not as simple as one effect applying to the cognitive domain, and one to the domain of motor skills, and it’s a little mysterious why pressure could have too such opposite effects (drawing attention away, or toward). This new study carried out four experiments in order to define more precisely the characteristics of the environment that lead to these different effects, and suggest solutions to the problem.

In the first experiment, participants were given a category learning task, in which some categories had only one relevant dimension and could be distinguished according to one easily articulated rule, and others involved three relevant dimensions and one irrelevant one. Categorization in this case was based on a complex rule that would be difficult to verbalize, and so participants were expected to integrate the information unconsciously.

Rule-based category learning was significantly worse when participants were also engaged in a secondary task requiring them to monitor briefly appearing letters. However it was not affected when their secondary task involved them explicitly monitoring the categorization task and making a confidence judgment. On the other hand, the implicit category learning task was not disrupted by the letter-monitoring task, but was impaired by the confidence-judgment task. Further analysis revealed that participants who had to do the confidence-judgment task were less likely to use the best strategy, but instead persisted in trying to verbalize a one- or two-dimension rule.

In the second experiment, the same tasks were learned in a low-pressure baseline condition followed by either a low-pressure control condition or one of two high-pressure conditions. One of these revolved around outcome — participants would receive money for achieving a certain level of improvement in their performance. The other put pressure on the participants through monitoring — they were watched and videotaped, and told their performance would be viewed by other students and researchers.

Rule-based category learning was slower when the pressure came from outcomes, but not when the pressure came from monitoring. Implicit category learning was unaffected by outcome pressure, but worsened by monitoring pressure.

Both high-pressure groups reported the same levels of pressure.

Experiment 3 focused on the detrimental combinations — rule-based learning under outcome pressure; implicit learning under monitoring pressure — and added the secondary tasks from the first experiment.

As predicted, rule-based categories were learned more slowly during conditions of both outcome pressure and the distracting letter-monitoring task, but when the secondary task was confidence-judgment, the negative effect of outcome pressure was counteracted and no impairment occurred. Similarly, implicit category learning was slowed when both monitoring pressure and the confidence-judgment distraction were applied, but was unaffected when monitoring pressure was counterbalanced by the letter task.

The final experiment extended the finding of the second experiment to another domain — procedural learning. As expected, the motor task was significantly affected by monitoring pressure, but not by outcome pressure.

These findings suggest two different strategies for dealing with choking, depending on the situation and the task. In the case of test-taking, good test preparation and a writing exercise can boost performance by reducing anxiety and freeing up working memory. If you're worried about doing well in a game or giving a memorized speech in front of others, you instead want to distract yourself so you don't become focused on the details of what you're doing.



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Stereotype threat's effect on black students' academic achievement

August, 2011

Another study on the dramatic impact of stereotype threat on academic achievement, and how you can counter it.

In a two-part experiment, Black and White students studied the definitions of 24 obscure English words, and were later tested, in threatening or non-threatening environments. In the threatening study environment, students were told that the task would assess their "learning abilities and limitations" and "how well people from different backgrounds learn”. In the non-threatening environment, students were told that the study focused on identifying "different learning styles". When tested one to two weeks later, students were first given a low-stress warm-up exercise with half of the word definitions. Then, in order to evoke concerns about stereotypes, a test was given which was described as evaluating "your ability to learn verbal information and your performance on problems requiring verbal reasoning ability".

The effect of these different environments on the Black students was dramatic. On the non-threatening warm-up test, Black students who had studied in the threatening learning environment performed about 50% worse than Black students who had studied in the non-threatening environment. But on the ‘real’ test, for which stereotypes had been evoked, all the Blacks — including those who had done fine on the warm-up — did poorly.

In the second experiment, only Black students were involved, and they all studied in the threatening environment. This time, however, half of the students were asked to begin with a "value affirmation" exercise, during which they chose values that mattered most to them and explained why. The other students were asked to write about a value that mattered little to them. A week later, students did the warm-up and the test. Black students who had written about a meaningful value scored nearly 70% better on the warm-up than black students who had written about other values.


[2348] Taylor VJ, Walton GM. Stereotype Threat Undermines Academic Learning. Personality and Social Psychology Bulletin [Internet]. 2011 ;37(8):1055 - 1067. Available from:



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Meditation's cognitive benefits

A critical part of attention (and working memory capacity) is being able to ignore distraction. There has been growing evidence that meditation training (in particular mindfulness meditation) helps develop attentional control, and that this can start to happen very quickly.

For example:

  • after an eight-week course that included up to 30 minutes of daily meditation, novices improved their ability to quickly and accurately move and focus attention.
  • three months of rigorous training in Vipassana meditation improved attentional control.
  • after eight weeks of Mindfulness Training, Marine reservists during pre-deployment showed increased working memory capacity and decreased negative mood (this training also included concrete applications for the operational environment and information and skills about stress, trauma and resilience in the body).
  • after a mere four sessions of 20 minutes, students produced a significant improvement in critical cognitive skills — and a dramatic improvement when conditions became more stressful (provided by increasingly challenging time-constraints).

There seem to be several factors involved in these improvements: better control of brainwaves; increased gray matter density in some brain regions; improved white-matter connectivity.

Thus, after ten weeks of Transcendental Meditation (TM) practice, students showed significant changes in brainwave patterns during meditation compared to eyes-closed rest for the controls. These changes reflected greater coherence and power in brainwave activity in areas that overlap with the default mode network (the brain’s ‘resting state’). Similarly, after an eight-week mindfulness meditation program, participants had better control of alpha brainwaves. Relatedly, perhaps, experienced Zen meditators have shown that, after interruptions designed to mimic spontaneous thoughts, they could bring activity in most regions of the default mode network back to baseline faster than non-meditators.

Thus, after an 8-week mindfulness meditation program, participants showed increased grey-matter density in the left hippocampus , posterior cingulate cortex, temporo-parietal junction , and cerebellum , as well as decreased grey-matter density in the amygdala . Similarly, another study found experienced meditators showed significantly larger volumes of the right hippocampus and the right orbitofrontal cortex, and to a lesser extent the right thalamus and the left inferior temporal gyrus.

These areas of the brain are all closely linked to emotion, and may explain meditators' improved ability in regulating their emotions.

Thus, long-term meditators showed pronounced differences in white-matter connectivity between their brains and those of age-matched controls, meaning that meditators’ brains were better able to quickly relay electrical signals. The brain regions linked by these white-matter tracts include many of those mentioned as showing increased gray matter density. Another study found that a mere 11 hours of meditation training (IBMT) produced measurable changes in the integrity and efficiency of white matter in the corona radiata (which links to the anterior cingulate cortex, an area where attention and emotion are thought to be integrated).

It’s an interesting question, the extent to which poor attentional control is a reflection of poor emotional regulation. Obviously there is more to distractability than that, but emotion and attention are clearly inextricably entwined. So, for example, a pilot study involving 10 middle school students with ADHD found that those who participated in twice-daily 10 minute sessions of Transcendental Meditation for three months showed a dramatic reduction in stress and anxiety and improvements in ADHD symptoms and executive function.

The effects of emotion regulation are of course wider than the effects on attention. Another domain they impact is that of decision-making. A study involving experienced Buddhist meditators found that they used different brain regions than controls when making decisions in a ‘fairness’ game. The differences reflected less input from emotional reactions and more emphasis on the actual benefits.

Similarly, brain scans taken while experienced and novice meditators meditated found that periodic bursts of disturbing noise had less effect on brain areas involved in emotion and decision-making for experienced meditators compared to novices — and very experienced meditators (at least 40,000 hours of experience) showed hardly any activity in these areas at all.

Attention is also entwined with perception, so it’s also interesting to observe that several studies have found improved visual perception attendant on meditation training and/or experience. Thus, participants attending a three-month meditation retreat, showed significant improvements in making fine visual distinctions, and ability to sustain attention.

But such benefits may depend on the style of meditation. A study involving experienced practitioners of two styles of meditation (Deity Yoga (DY) and Open Presence (OP)) found that DY meditators were dramatically better at mental rotation and visual memory tasks compared to OP practitioners and controls (and only if they were given the tasks immediately after meditating). Similarly, a study involving Tibetan Buddhist monks found that, during "one-point" meditation, monks were significantly better at maintaining their focus on one image, when two different images were presented to each eye. This superior attentional control was not found during compassion-oriented meditation. However, even under normal conditions the monks showed longer stable perception compared to meditation-naïve control subjects. And three months of intense training in Vipassana meditation produced an improvement in the ability of participants to detect the second of two visual signals half a second apart (the size of the improvement was linked to reduced brain activity to the first target — which was still detected with the same level of accuracy). Similarly, three months of intensive meditation training reduced variability in attentional processing of target tones.


You can read about these studies below in more detail. Three studies were mentioned here without having appeared in the news reports:

Lutz, A., Slagter, H. A., Rawlings, N. B., Francis, A. D., Greischar, L. L., & Davidson, R. J. (2009). Mental Training Enhances Attentional Stability: Neural and Behavioral Evidence. J. Neurosci., 29(42), 13418-13427. doi:10.1523/JNEUROSCI.1614-09.2009

Tang, Y.-Y., Lu, Q., Geng, X., Stein, E. A., Yang, Y., & Posner, M. I. (2010). Short-term meditation induces white matter changes in the anterior cingulate. Proceedings of the National Academy of Sciences, 107(35), 15649 -15652. doi:10.1073/pnas.1011043107

Travis, F., Haaga, D., Hagelin, J., Tanner, M., Arenander, A., Nidich, S., Gaylord-King, C., et al. (2010). A self-referential default brain state: patterns of coherence, power, and eLORETA sources during eyes-closed rest and Transcendental Meditation practice. Cognitive Processing, 11(1), 21-30. doi:10.1007/s10339-009-0343-2

Older news items (pre-2010) brought over from the old website

More on how meditation can improve attention

Another study adds to research showing meditation training helps people improve their ability to focus and ignore distraction. The new study shows that three months of rigorous training in Vipassana meditation improved people's ability to stabilize attention on target tones, when presented with tones in both ears and instructed to respond only to specific tones in one ear. Marked variability in response time is characteristic of those with ADHD.

[1500] Lutz A, Slagter HA, Rawlings NB, Francis AD, Greischar LL, Davidson RJ. Mental Training Enhances Attentional Stability: Neural and Behavioral Evidence. J. Neurosci. [Internet]. 2009 ;29(42):13418 - 13427. Available from:

Meditation may increase gray matter

Adding to the increasing evidence for the cognitive benefits of meditation, a new imaging study of 22 experienced meditators and 22 controls has revealed that meditators showed significantly larger volumes of the right hippocampus and the right orbitofrontal cortex, and to a lesser extent the right thalamus and the left inferior temporal gyrus. There were no regions where controls had significantly more gray matter than meditators. These areas of the brain are all closely linked to emotion, and may explain meditators' improved ability in regulating their emotions.

[1055] Luders E, Toga AW, Lepore N, Gaser C. The underlying anatomical correlates of long-term meditation: Larger hippocampal and frontal volumes of gray matter. NeuroImage [Internet]. 2009 ;45(3):672 - 678. Available from:

Meditation technique can temporarily improve visuospatial abilities

And continuing on the subject of visual short-term memory, a study involving experienced practitioners of two styles of meditation: Deity Yoga (DY) and Open Presence (OP) has found that, although meditators performed similarly to nonmeditators on two types of visuospatial tasks (mental rotation and visual memory), when they did the tasks immediately after meditating for 20 minutes (while the nonmeditators rested or did something else), practitioners of the DY style of meditation showed a dramatic improvement compared to OP practitioners and controls. In other words, although the claim that regular meditation practice can increase your short-term memory capacity was not confirmed, it does appear that some forms of meditation can temporarily (and dramatically) improve it. Since the form of meditation that had this effect was one that emphasizes visual imagery, it does support the idea that you can improve your imagery and visual memory skills (even if you do need to ‘warm up’ before the improvement is evident).

[860] Kozhevnikov M, Louchakova O, Josipovic Z, Motes MA. The enhancement of visuospatial processing efficiency through Buddhist Deity meditation. Psychological Science: A Journal of the American Psychological Society / APS [Internet]. 2009 ;20(5):645 - 653. Available from:

Transcendental Meditation reduces ADHD symptoms among students

A pilot study involving 10 middle school students with ADHD has found that those who participated in twice-daily 10 minute sessions of Trancendental Meditation for three months showed a dramatic reduction in stress and anxiety and improvements in ADHD symptoms and executive function. The effect was much greater than expected. ADHD children have a reduced ability to cope with stress.
A second, recently completed study has also found that three months practice of the technique resulted in significant positive changes in brain functioning during visual-motor skills, especially in the circuitry of the brain associated with attention and distractibility. After six months practice, measurements of distractibility moved into the normal range.

Grosswald, S. J., Stixrud, W. R., Travis, F., & Bateh, M. A. (2008, December). Use of the Transcendental Meditation technique to reduce symptoms of Attention Deficit Hyperactivity Disorder (ADHD) by reducing stress and anxiety: An exploratory study. Current Issues in Education [On-line], 10(2). Available:

Meditation speeds the mind's return after distraction

Another study comparing brain activity in experienced meditators and novices has looked at what happens when people meditating were interrupted by stimuli designed to mimic the appearance of spontaneous thoughts. The study compared 12 people with more than three years of daily practice in Zen meditation with 12 others who had never practiced meditation. It was found that, after interruption, experienced meditators were able to bring activity in most regions of the default mode network (especially the angular gyrus, a region important for processing language) back to baseline faster than non-meditators. The default mode network is associated with the occurrence of spontaneous thoughts and mind-wandering during wakeful rest. The findings indicate not only the attentional benefits of meditation, but also suggest a value for disorders characterized by excessive rumination or an abnormal production of task-unrelated thoughts, such as obsessive-compulsive disorder, anxiety disorder and major depression.

[910] Pagnoni G, Cekic M, Guo Y. “Thinking about Not-Thinking”: Neural Correlates of Conceptual Processing during Zen Meditation. PLoS ONE [Internet]. 2008 ;3(9):e3083 - e3083. Available from:

Full text available at

Improved attention with mindfulness training

More evidence of the benefits of meditation for attention comes from a study looking at the performance of novices taking part in an eight-week course that included up to 30 minutes of daily meditation, and experienced meditators who attended an intensive full-time, one-month retreat. Initially, the experienced participants demonstrated better executive functioning skills, the cognitive ability to voluntarily focus, manage tasks and prioritize goals. After the eight-week training, the novices had improved their ability to quickly and accurately move and focus attention, while the experienced participants, after their one-month intensive retreat, also improved their ability to keep attention "at the ready."

[329] Jha AP, Krompinger J, Baime MJ. Mindfulness training modifies subsystems of attention. Cognitive, Affective & Behavioral Neuroscience [Internet]. 2007 ;7(2):109 - 119. Available from:

Brain scans show how meditation affects the brain

An imaging study comparing novice and experienced meditators found that experienced meditators showed greater activity in brain circuits involved in paying attention. But the most experienced meditators with at least 40,000 hours of experience showed a brief increase in activity as they started meditating, and then a drop to baseline, as if they were able to concentrate in an effortless way. Moreover, while the subjects meditated inside the MRI, the researchers periodically blasted them with disturbing noises. Among the experienced meditators, the noise had less effect on the brain areas involved in emotion and decision-making than among novice meditators. Among meditators with more than 40,000 hours of lifetime practice, these areas were hardly affected at all. The attention circuits affected by meditation are also involved in attention deficit hyperactivity disorder.

[1364] Brefczynski-Lewis JA, Lutz A, Schaefer HS, Levinson DB, Davidson RJ. Neural correlates of attentional expertise in long-term meditation practitioners. Proceedings of the National Academy of Sciences [Internet]. 2007 ;104(27):11483 - 11488. Available from:

Full text is available at

Meditation may improve attentional control

Paying attention to one thing can keep you from noticing something else. When people are shown two visual signals half a second apart, they often miss the second one — this effect is called the attentional blink. In a study involving 40 participants being trained in Vipassana meditation (designed to reduce mental distraction and improve sensory awareness), one group of 17 attended a 3 month retreat during which they meditated for 10–12 hours a day (practitioner group), and 23 simply received a 1-hour meditation class and were asked to meditate for 20 minutes daily for 1 week prior to each testing session (control group). The three months of intense training resulted in a smaller attentional blink and reduced brain activity to the first target (which was still detected with the same level of accuracy. Individuals with the most reduction in activity generally showed the most reduction in attentional blink size. The study demonstrates that mental training can result in increased attentional control.

[1153] Slagter HA, Lutz A, Greischar LL, Francis AD, Nieuwenhuis S, Davis JM, Davidson RJ. Mental Training Affects Distribution of Limited Brain Resources. PLoS Biol [Internet]. 2007 ;5(6):e138 - e138. Available from:

Full text available at

Meditation skills of Buddhist monks yield clues to brain's regulation of attention

Recent research has suggested that skilled meditation can alter certain aspects of the brain's neural activity. A new study has now found evidence that certain types of trained meditative practice can influence the conscious experience of visual perceptual rivalry, a phenomenon thought to involve brain mechanisms that regulate attention and conscious awareness. Perceptual rivalry arises normally when two different images are presented to each eye, and it is manifested as a fluctuation in the "dominant" image that is consciously perceived. The study involved 76 Tibetan Buddhist monks with training ranging from 5 to 54 years. Tested during the practice of two types of meditation: a "compassion"-oriented meditation (contemplation of suffering within the world), and "one-point" meditation (involving the maintained focus of attention on a single object or thought). Major increases in the durations of perceptual dominance were experienced by monks practicing one-point meditation, but not during compassion-oriented meditation. Additionally, under normal conditions the monks showed longer stable perception (average 4.1 seconds compared to 2.6 seconds for meditation-naïve control subjects). The findings suggest that processes particularly associated with one-point meditation can considerably alter the normal fluctuations in conscious state that are induced by perceptual rivalry.

[350] Carter O, Presti D, Callistemon C, Ungerer Y, Liu G, Pettigrew J. Meditation alters perceptual rivalry in Tibetan Buddhist monks. Current Biology [Internet]. 2005 ;15(11):R412-R413 - R412-R413. Available from:

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