meditation

Mindfulness may increase susceptibility to false memories

  • Mindfulness meditation is associated in many studies with cognitive benefits, especially in attention.
  • In a new study, a brief guided meditation exercise increased students' false recognition of words as ones they had seen earlier.
  • It may be that the non-judgmental mindset encouraged by mindfulness meditation reduces people's ability to clearly remember the source of a memory, thus making them more susceptible to false memories.
  • Source memory also tends to be negatively affected by increasing age.

Mindfulness meditation is associated with various positive benefits, one of which is improved attention, but it might not be all good. A new study suggests that it may have negative cognitive consequences.

The study included three experiments, in the first two of which undergraduates carried out a 15-minute guided exercise: one group was instructed to focus attention on their breathing without judgment (mindfulness group); the other group was told to think about whatever came to mind (mind-wandering group; the control).

In the first experiment, 153 participants then studied a list of 15 words related to the concept of trash, but not including the word "trash". When then asked to recall as many of the words from the list as they could remember, 39% of the mindfulness group falsely recalled seeing the word "trash" on the list compared to only 20% of the mind-wandering group. There was no difference between the groups in the number of other words falsely recalled.

In the second experiment, 140 participants were compared to themselves, before and after the intervention. They all began by doing six of the same sort of word lists. They were then randomly assigned either the meditation exercise or the mind-wandering. This was then followed by a further six word lists.

Again, mindfulness participants were more likely to falsely recall the critical word than those who engaged in mind wandering. Those in the mind-wandering group showed no difference in performance on the word lists before and after, while those in the meditation group were significantly more likely to falsely remember the critical item. Again, there were no other differences in performance between the groups: they correctly recalled about the same number of words, and they falsely remembered about the same number of other words.

In the third experiment, 215 undergraduates had to determine whether a word had been presented earlier, where the words shown were all part of a strongly associated pair (e.g., foot-shoe). After seeing the 100 words (for 1.5 seconds each), they were then tested. Each word had an equal chance of being one of the words in the presented list, or its associated pair. All students were then given the 15-minute meditation exercise, before going through the process again.

Again, the rate of words correctly identified as seen before was about the same before and after the meditation exercise, but the rate of words falsely identified increased significantly after the exercise.

In all, then, it seems that mindfulness meditation increased participants' susceptibility to false memories, reducing their ability to differentiate items they actually encountered from items they only imagined (because of their strong association to the items encountered).

The researchers speculate that the mechanism that seems to underlie the benefits of mindfulness — judgment-free thoughts and feelings — might also affect people's ability to determine the origin of a given memory (source memory), because they have become less able to distinguish between externally occurring events and internally generated events.

Source memory is one of those memory domains that tend to be affected by aging. However, the benefits of meditation for improving attention — another area particularly affected by age — outweigh this downside. So I'm certainly not suggesting anyone should be put off by this finding!

An interesting question that remains to be answered is whether this negative effect on source memory is short-lived, or whether experienced meditators tend to have poorer source memory.

http://www.eurekalert.org/pub_releases/2015-09/afps-mmm090915.php

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Why older adults lose working memory capacity

The root of age-related cognitive decline may lie in a reduced ability to ignore distractors. A new study indicates that older adults put more effort into focusing during encoding, in order to compensate for a reduced ability to hold information in working memory. The finding suggests a multi-pronged approach to improving cognitive ability in older adults.

I've reported before on the idea that the drop in working memory capacity commonly seen in old age is related to the equally typical increase in distractability. Studies of brain activity have also indicated that lower WMC is correlated with greater storage of distractor information. So those with higher WMC, it's thought, are better at filtering out distraction and focusing only on the pertinent information. Older adults may show a reduced WMC, therefore, because their ability to ignore distraction and irrelevancies has declined.

Why does that happen?

A new, large-scale study using a smartphone game suggests that the root cause is a change in the way we hold items in working memory.

The study involved 29,631 people aged 18—69, who played a smartphone game in which they had to remember the positions of an increasing number of red circles. Yellow circles, which had to be ignored, could also appear — either at the same time as the red circles, or after them. Data from this game revealed both WMC (how many red circle locations the individual could remember), and distractability (how many red circle locations they could remember in the face of irrelevant yellow circles).

Now this game isn't simply a way of measuring WMC. It enables us to make an interesting distinction based on the timing of the distraction. If the yellow circles appeared at the same time as the red ones, they are providing distraction when you are trying to encode the information. If they appear afterward, the distraction occurs when you are trying to maintain the information in working memory.

Now it would seem commonsensical that distraction at the time of encoding must be the main problem, but the fascinating finding of this study is that it was distraction during the delay (while the information is being maintained in working memory) that was the greater problem. And it was this distraction that became more and more marked with increasing age.

The study is a follow-up to a smaller 2014 study that included two experiments: a lab experiment involving 21 young adults, and data from the same smartphone game involving only the younger cohort (18-29 years; 3247 participants).

This study demonstrated that distraction during encoding and distraction during delay were independent contributory factors to WMC, suggesting that separate mechanisms are involved in filtering out distraction at encoding and maintenance.

Interestingly, analysis of the data from the smartphone game did indicate some correlation between the two in that context. One reason may be that participants in the smartphone game were exposed to higher load trials (the lab study kept WM load constant); another might be that they were in more distracting environments.

While in general researchers have till now assumed that the two processes are not distinct, it has been theorized that distractor filtering at encoding may involve a 'selective gating mechanism', while filtering during WM maintenance may involve a shutting down of perception. The former has been linked to a gating mechanism in the striatum in the basal ganglia, while the latter has been linked to an increase in alpha waves in the frontal cortex, specifically, the left middle frontal gyrus. The dorsolateral prefrontal cortex may also be involved in distractor filtering at encoding.

To return to the more recent study:

  • there was a significant decrease in WMC with increasing age in all conditions (no distraction; encoding distraction; delay distraction)
  • for older adults, the decrease in WMC was greatest in the delay distraction condition
  • when 'distraction cost' was calculated (((ND score − (ED or DD score))/ND score) × 100), there was a significant correlation between delay distraction cost and age, but not between encoding distraction cost and age
  • for older adults, performance in the encoding distraction condition was better predicted by performance in the no distraction condition than it was among the younger groups
  • this correlation was significantly different between the 30-39 age group and the 40-49 age group, between the 40s and the 50s, and between the 50s and the 60s — showing that this is a progressive change
  • older adults with a higher delay distraction cost (ie, those more affected by distractors during delay) also showed a significantly greater correlation between their no-distraction performance and encoding-distraction performance.

All of this suggests that older adults are focusing more attention during attention even when there is no distraction, and they are doing so to compensate for their reduced ability to maintain information in working memory.

This suggests several approaches to improving older adults' ability to cope:

  • use perceptual discrimination training to help improve WMC
  • make working memory training more about learning to ignore certain types of distraction
  • reduce distraction — modify daily tasks to make them more "older adult friendly"
  • (my own speculation) use meditation training to improve frontal alpha rhythms.

You can participate in the game yourself, at http://thegreatbrainexperiment.com/

http://medicalxpress.com/news/2015-05-smartphone-reveals-older.html

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[3921] McNab F, Zeidman P, Rutledge RB, Smittenaar P, Brown HR, Adams RA, Dolan RJ. Age-related changes in working memory and the ability to ignore distraction. Proceedings of the National Academy of Sciences [Internet]. 2015 ;112(20):6515 - 6518. Available from: http://www.pnas.org/content/112/20/6515

McNab, F., & Dolan, R. J. (2014). Dissociating distractor-filtering at encoding and during maintenance. Journal of Experimental Psychology. Human Perception and Performance, 40(3), 960–7. doi:10.1037/a0036013

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Evidence for the benefits of meditation in fighting age-related cognitive decline

A review of meditation research reported in January last year concluded that there were insufficient good studies to allow us to say that meditation clearly improves attention and cognition. Studies from 2014 suggest three factors that might be part of the reason for inconsistent research findings:

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Meditating leads to better grades

Three classroom experiments have found that students who meditated before a psychology lecture scored better on a quiz that followed than students who did not meditate. Mood, relaxation, and class interest were not affected by the meditation training.

The noteworthy thing is that the meditation was very very basic — six minutes of written meditation exercises.

The effect was stronger in classes where more freshmen students were enrolled, suggesting that the greatest benefit is to those students who have most difficulty in concentrating (who are more likely to drop out).

05/2013

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Intensive training helps seniors with long-term aphasia

February, 2013

A six-week specific language therapy program not only improved chronic aphasic’s ability to name objects, but produced durable changes in brain activity that continued to bring benefits post-training.

Here’s an encouraging study for all those who think that, because of age or physical damage, they must resign themselves to whatever cognitive impairment or decline they have suffered. In this study, older adults who had suffered from aphasia for a long time nevertheless improved their language function after six weeks of intensive training.

The study involved nine seniors with chronic aphasia and 10 age-matched controls. Those with aphasia were given six weeks of intensive and specific language therapy, after which they showed significantly better performance at naming objects. Brain scans revealed that the training had not only stimulated language circuits, but also integrated the default mode network (the circuits used when our brain is in its ‘resting state’ — i.e., not thinking about anything in particular), producing brain activity that was similar to that of the healthy controls.

Moreover, these new circuits continued to be active after training, with participants continuing to improve.

Previous research has implicated abnormal functioning of the default mode network in other cognitive disorders.

Although it didn’t reach significance, there was a trend suggesting that the level of integration of the default mode network prior to therapy predicted the outcome of the training.

The findings are especially relevant to the many seniors who no longer receive treatment for stroke damage they may have had for many years. They also add to the growing evidence for the importance of the default mode network. Changes in the integration of the default mode network with other circuits have also been implicated in age-related cognitive decline and Alzheimer’s.

Interestingly, some research suggests that meditation may help improve the coherence of brainwaves that overlap the default mode network. Meditation, already shown to be helpful for improving concentration and focus, may be of greater benefit for fighting age-related cognitive decline than we realize!

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