Strategies

When age helps decision making

October, 2011

New study modifies findings that younger adults are better decision-makers by showing older adults are better when the scenarios involve multiple considerations.

Research has shown that younger adults are better decision makers than older adults — a curious result. A new study tried to capture more ‘real-world’ decision-making, by requiring participants to evaluate each result in order to strategize the next choice.

This time (whew!), the older adults did better.

In the first experiment, groups of older (60-early 80s) and younger (college-age) adults received points each time they chose from one of four options and tried to maximize the points they earned.  For this task, the younger adults were more efficient at selecting the options that yielded more points.

In the second experiment, the rewards received depended on the choices made previously.  The “decreasing option” gave a larger number of points on each trial, but caused rewards on future trials to be lower. The “increasing option” gave a smaller reward on each trial but caused rewards on future trials to increase.  In one version of the test, the increasing option led to more points earned over the course of the experiment; in another, chasing the increasing option couldn’t make up for the points that could be accrued grabbing the bigger bite on each trial.

The older adults did better on every permutation.

Understanding more complex scenarios is where experience tells. The difference in performance also may reflect the different ways younger and older adults use their brains. Decision-making can involve two different reward learning systems, according to recent thinking. In the model-based system, a cognitive model is constructed that shows how various actions and their rewards are connected to each other. Decisions are made by simulating how one decision will affect future decisions. In the model-free system, on the other hand, only values associated with each choice are considered.

These systems are rooted in different parts of the brain. The model-based system uses the intraparietal sulcus and lateral prefrontal cortex, while the model-free system uses the ventral striatum. There is some evidence that younger adults use the ventral striatum (involved in habitual, reflexive learning and immediate reward) for decision-making more than older adults, and older adults use the dorsolateral prefrontal cortex (involved in more rational, deliberative thinking) more than younger adults.

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Memory fitness program improves memory abilities of oldest adults

October, 2011

A six-week memory fitness program offered to older adults helped improve their ability to recognize and recall words.

In a study involving 115 seniors (average age 81), those who participated in a six-week, 12-session memory training program significantly improved their verbal memory. 15-20 seniors participated in each hour-long class, which included explanations of how memory works, quick strategies for remembering names, faces and numbers, basic memory strategies such as linking ideas and creating visual images, and information on a healthy lifestyle for protecting and maintaining memory.

Most of the study participants were women, Caucasian and had attained a college degree or higher level of education.

Reference: 

[2491] Miller, K. J., Siddarth P., Gaines J. M., Parrish J. M., Ercoli L. M., Marx K., et al.
(2011).  The Memory Fitness Program.
American Journal of Geriatric Psychiatry. 1 - 1.

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Errorless learning not always best for older brains

October, 2011

New evidence challenges the view that older adults learn best through errorless learning. Trial-and-error learning can be better if done the right way.

Following a 1994 study that found that errorless learning was better than trial-and-error learning for amnesic patients and older adults, errorless learning has been widely adopted in the rehabilitation industry. Errorless learning involves being told the answer without repeatedly trying to answer the question and perhaps making mistakes. For example, in the 1994 study, participants in the trial-and-error condition could produce up to three errors in answer to the question “I am thinking of a word that begins with QU”, before being told the answer was QUOTE; in contrast, participants in the errorless condition were simply told “I am thinking of a word that begins with QU and it is ‘QUOTE’.”

In a way, it is surprising that errorless learning should be better, given that trial-and-error produces much deeper and richer encoding, and a number of studies with young adults have indeed found an advantage for making errors. Moreover, it’s well established that retrieving an item leads to better learning than passively studying it, even when you retrieve the wrong item. This testing effect has also been found in older adults.

In another way, the finding is not surprising at all, because clearly the trial-and-error condition offers many opportunities for confusion. You remember that QUEEN was mentioned, for example, but you don’t remember whether it was a right or wrong answer. Source memory, as I’ve often mentioned, is particularly affected by age.

So there are good theoretical reasons for both positions regarding the value of mistakes, and there’s experimental evidence for both. Clearly it’s a matter of circumstance. One possible factor influencing the benefit or otherwise of error concerns the type of processing. Those studies that have found a benefit have generally involved conceptual associations (e.g. What’s Canada’s capital? Toronto? No, Ottawa). It may be that errors are helpful to the extent that they act as retrieval cues, and evoke a network of related concepts. Those studies that have found errors harm learning have generally involved perceptual associations, such as word stems and word fragments (e.g., QU? QUeen? No, QUote). These errors are arbitrary, produce interference, and don’t provide useful retrieval cues.

So this new study tested the idea that producing errors conceptually associated with targets would boost memory for the encoding context in which information was studied, especially for older adults who do not spontaneously elaborate on targets at encoding.

In the first experiment, 33 young (average age 21) and 31 older adults (average age 72) were shown 90 nouns presented in three different, intermixed conditions. In the read condition (designed to provide a baseline), participants read aloud the noun fragment presented without a semantic category (e.g., p­_g). In the errorless condition, the semantic category was presented with the target word fragment (e.g. a farm animal  p­_g), and the participants read aloud the category and their answer. The category and target were then displayed. In the trial-and-error condition, the category was presented and participants were encouraged to make two guesses before being shown the target fragment together with the category. The researchers changed the target if it was guessed. Participants were then tested using a list of 70 words, of which 10 came from each of the study conditions, 10 were new unrelated words, and 30 were nontarget exemplars from the TEL categories. Those that the subject had guessed were labeled as learning errors; those that hadn’t come up were labeled as related lures. In addition to an overall recognition test (press “yes” to any word you’ve studied and “no” to any new word), there were two tests that required participants to endorse items that were studied in the TEL condition and reject those studied in the EL condition, and vice versa.

The young adults did better than the older on every test. TEL produced better learning than EL, and both produced better learning than the read condition (as expected). The benefit of TEL was greater for older adults. This is in keeping with the idea that generating exemplars of a semantic category, as occurs in trial-and-error learning, helps produce a richer, more elaborated code, and that this is of greater to older adults, who are less inclined to do this without encouragement.

There was a downside, however. Older adults were also more prone to falsely endorsing prior learning errors or semantically-related lures. It’s worth noting that both groups were more likely to falsely endorse learning errors than related lures.

But the main goal of this first experiment was to disentangle the contributions of recollection and familiarity to the two types of learning. It turns out that there was no difference between young and older adults in terms of familiarity; the difference in performance between the two groups stemmed from recollection. Recollection was a problem for older adults in the errorless condition, but not in the trial-and-error condition (where the recollective component of their performance matched that of young adults). This deficit is clearly closely related to age-related deficits in source memory.

It was also found that familiarity was marginally more important in the errorless condition than the trial-and-error condition. This is consistent with the idea that targets learned without errors acquire greater fluency than those learned with errors (with the downside that they don’t pick up those contextual details that making errors can provide).

In the second experiment, 15 young and 15 older adults carried out much the same procedure, except that during the recognition test they were also required to mention the context in which the words were learned was tested (that is, were the words learned through trial-and-error or not).

Once again, trial-and-error learning was associated with better source memory relative to errorless learning, particularly for the older adults.

These results support the hypothesis that trial-and-error learning is more beneficial than errorless learning for older adults when the trials encourage semantic elaboration. But another factor may also be involved. Unlike other errorless studies, participants were required to attend to errors as well as targets. Explicit attention to errors may help protect against interference.

In a similar way, a recent study involving young adults found that feedback given in increments (thus producing errors) is more effective than feedback given all at once in full. Clearly what we want is to find that balance point, where elaborative benefits are maximized and interference is minimized.

Reference: 

[2496] Cyr, A-A., & Anderson N. D.
(2011).  Trial-and-error learning improves source memory among young and older adults.
Psychology and Aging. No Pagination Specified - No Pagination Specified.

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Whether couple’s collaborative dialogue helps spouse's memory

September, 2011

A small study suggests that middle-aged couples are more likely to be effective than older couples in helping fill in each other’s memory gaps, but effective collaboration also depends on conversational style.

In my book on remembering what you’re doing and what you intend to do, I briefly discuss the popular strategy of asking someone to remind you (basically, whether it’s an effective strategy depends on several factors, of which the most important is the reliability of the person doing the reminding). So I was interested to see a pilot study investigating the use of this strategy between couples.

The study confirms earlier findings that the extent to which this strategy is effective depends on how reliable the partner's memory is, but expands on that by tying it to age and conversational style.

The study involved 11 married couples, of whom five were middle-aged (average age 52), and six were older adults (average age 73). Participants completed a range of prospective memory tasks by playing the board game "Virtual Week," which encourages verbal interaction among players about completing real life tasks. For each virtual "day" in the game, participants were asked to perform 10 different prospective memory tasks — four that regularly occur (eg, taking medication with breakfast), four that were different each day (eg, purchasing gasoline for the car), and two being time-check tasks that were not based on the activities of the board game (eg, check lung capacity at two specified times).

Overall, the middle-aged group benefited more from collaboration than the older group. But it was also found that those couples who performed best were those who were more supportive and encouraging of each other.

Collaboration in memory tasks is an interesting activity, because it can be both helpful and hindering. Think about how memory works — by association. You start from some point, and if you’re on a good track, more and more should be revealed as each memory triggers another. If another person keeps interrupting your train, you can be derailed. On the other hand, they might help you fill you in gaps that you need, or even point you to the right track, if you’re on the wrong one.

In this small study, it tended to be the middle-aged couples that filled in the gaps more effectively than the older couples. That probably has a lot to do with memory reliability. So it’s not a big surprise (though useful to be aware of). But what I find more interesting (because it’s less obvious, and more importantly, because it’s more under our control) is this idea that our conversational style affects whether memory collaboration is useful or counterproductive. I look forward to results from a larger study.

Reference: 

[2490] Margrett, J. A., Reese-Melancon C., & Rendell P. G.
(2011).  Examining Collaborative Dialogue Among Couples.
Zeitschrift für Psychologie / Journal of Psychology. 219, 100 - 107.

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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.)

Reference: 

[2338] Cohen, D. A., & Robertson E. M.
(2011).  Preventing interference between different memory tasks.
Nat Neurosci. 14(8), 953 - 955.

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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.

http://www.eurekalert.org/pub_releases/2009-11/uoh-wiu110409.php

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, J. S., Mattys S. L., & Gage S. H.
(2009).  Preserved implicit knowledge of a forgotten childhood language.
Psychological Science: A Journal of the American Psychological Society / APS. 20(9), 1064 - 1069.

http://www.eurekalert.org/pub_releases/2009-09/afps-uio092409.php

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.
(2009).  The bilingual advantage in novel word learning.
Psychonomic Bulletin & Review. 16(4), 705 - 710.

http://www.eurekalert.org/pub_releases/2009-05/nu-ett051909.php

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, A. M., & Mehler J.
(2009).  Cognitive gains in 7-month-old bilingual infants.
Proceedings of the National Academy of Sciences. 106(16), 6556 - 6560.

http://www.livescience.com/culture/090413-bilingual-smart.html

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, P. C. M., Warrier C. M., Penhune V. B., Roy A. K., Sadehh A., Parrish T. B., et al.
(2008).  Volume of Left Heschl's Gyrus and Linguistic Pitch Learning.
Cereb. Cortex. 18(4), 828 - 836.

http://www.physorg.com/news104599345.html

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, P. C. M., Skoe E., Russo N. M., Dees T., & Kraus N.
(2007).  Musical experience shapes human brainstem encoding of linguistic pitch patterns.
Nat Neurosci. 10(4), 420 - 422.

http://www.eurekalert.org/pub_releases/2007-03/nu-rfm031207.php

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, B. J., McVeigh N. D., Marful A., & Anderson M. C.
(2007).  Inhibiting your native language: the role of retrieval-induced forgetting during second-language acquisition.
Psychological Science: A Journal of the American Psychological Society / APS. 18(1), 29 - 34.

http://www.sciencedaily.com/releases/2007/01/070118094015.htm

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 F. I. M., & Freedman M.
(2007).  Bilingualism as a protection against the onset of symptoms of dementia.
Neuropsychologia. 45(2), 459 - 464.

http://www.eurekalert.org/pub_releases/2007-01/bcfg-css011107.php

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.

http://www.eurekalert.org/pub_releases/2006-10/dc-drf101706.php

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 D. W., Price C. J., Crinion J., Turner R., et al.
(2006).  Language Control in the Bilingual Brain.
Science. 312(5779), 1537 - 1540.

http://sciencenow.sciencemag.org/cgi/content/full/2006/608/2?etoc

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.
(2007).  Brain Structure Predicts the Learning of Foreign Speech Sounds.
Cereb. Cortex. 17(3), 575 - 582.

http://www.newscientist.com/article/dn8964

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.

http://www.nature.com/news/2005/050516/full/050516-1.html

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.

http://news.bbc.co.uk/2/hi/health/3739690.stm

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 F. I. M., Klein R., & Viswanathan M.
(2004).  Bilingualism, aging, and cognitive control: evidence from the Simon task.
Psychology and Aging. 19(2), 290 - 303.

http://news.bbc.co.uk/2/hi/health/3794479.stm

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.
(2004).  Neural correlates of second-language word learning: minimal instruction produces rapid change.
Nature Neuroscience. 7(7), 703 - 704.

http://www.eurekalert.org/pub_releases/2004-06/uow-baw061104.php

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.

http://www.eurekalert.org/pub_releases/2003-11/sfn-ssb111103.php

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.

http://www.eurekalert.org/pub_releases/2003-10/ps-bla101703.php

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 H. R., Abutalebi J., Cappa S. F., Villringer A., & Perani D.
(2003).  Early Setting of Grammatical Processing in the Bilingual Brain.
Neuron. 37(1), 159 - 170.

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, A. J., Bavelier D., Corina D., Jezzard P., & Neville H. J.
(2002).  A critical period for right hemisphere recruitment in American Sign Language processing.
Nat Neurosci. 5(1), 76 - 80.

http://www.eurekalert.org/pub_releases/2002-01/uow-sft010202.php

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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.

Reference: 

[2457] Vaughn, K. E., & Rawson K. A.
(2011).  Diagnosing Criterion-Level Effects on Memory.
Psychological Science.

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.

Reference: 

[2333] Addante, R. J., Watrous A. J., Yonelinas A. P., Ekstrom A. D., & Ranganath C.
(2011).  Prestimulus theta activity predicts correct source memory retrieval.
Proceedings of the National Academy of Sciences. 108(26), 10702 - 10707.

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