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DUAL N-BACK FAQ - expand your working memory and hopefully your IQ

Posted: Sat, April 27, 2013 | By: IQ

by Gwern Branwen N-back is a kind of mental training intended to expand your working memory (WM), and hopefully your intelligence (IQ1).

The theory originally went that novel2 cognitive processes tend to overlap and seem to go through one central bottleneck. As it happens, WM predicts and correlates with IQ3 and may use the same neural networks4, suggesting that WM might be IQ5. WM is known to be trainable, and so improving WM would hopefully improve IQ. And N-back is a family of tasks which stress attention and WM.

This essay was originally posted at Gwern’s site, HERE

Later research found that performance and improvement on N-back seems to correlate better with IQ rather than classic measures of WM like reciting lists of numbers, raising the question of whether N-back works via increasing WM or by improving self-control or improving manipulation of WM contents (rather than WM’s size) or somehow training IQ directly.6 Performance on DNB has complicated correlations with performance on other tests of working memory or IQ, so it’s not clear what it is tapping into. (And the link between WM and performance on IQ tests has been disputed; high WM as measured by OSPAN does not correlate well with performance on hard Raven’s questions7 and the validity of single tests of WM training has been questioned8.)

Brain Workshop offers many modes, some far more elaborate than simple Dual N-back; no research has been done on them, so little can be said about what they are good for or what they train or what improvements they may offer; Jaeggi 2010 seemed to find Single N-back better than Dual N-back. Some of the more elaborate modes seem to focus heavily on shifting the correct response among various modalities - not just sound, but left/right, eg. - and so stress context switches; there are results that task switching can be trained and that it transfers9, but how useful this is and how well the BW modes train this are unknown.



Working memory is important stuff for learning and also just general intelligence.10 It’s not too hard to see why working memory could be so important. Working memory boils down tohow much stuff you can think about at the same time.

Imagine a poor programmer who has suffered brain damage and has only enough working memory for 1 definition at a time. How could he write anything? To write a correct program, he needs to know simultaneously 2 things - what a variable, say, contains, and what is valid input for a program. But unfortunately, our programmer can know that the variable foocontains a string with the input, or he can know that the function processInput uses a string, but he can’t remember these 2 things simultaneously! He will deadlock forever, unsure either what to do with this foo, or unsure what exactly processInput was supposed to work on.

More seriously, working memory can be useful since it allows one to grasp more of the structure of something at any one time. Commentators on programming often write that one of the great challenges of programming (besides the challenge of accepting & dealing with the reality that a computer really is just a mindless rule-following machine), is that programming requires one to keep in mind dozens of things and circumstances - any one of which could completely bollix things up. Focus is absolutely essential. One of the characteristics of great programmers is their apparent omniscience. Obsession grants them this ability to know what they are actually doing:

> Several friends mentioned hackers’ ability to concentrate - their ability, as one put it, totune out everything outside their own heads. I’ve certainly noticed this. And I’ve heard several hackers say that after drinking even half a beer they can’t program at all. So maybe hacking does require some special ability to focus. Perhaps great hackers can load a large amount of context into their head, so that when they look at a line of code, they see not just that line but the whole program around it. John McPhee wrote that Bill Bradley’s success as a basketball player was due partly to his extraordinary peripheral vision. Perfect eyesight means about 47 degrees of vertical peripheral vision. Bill Bradley had 70; he could see the basket when he was looking at the floor. Maybe great hackers have some similar inborn ability. (I cheat by using a very dense language, which shrinks the court.) This could explain the disconnect over cubicles. Maybe the people in charge of facilities, not having any concentration to shatter, have no idea that working in a cubicle feels to a hacker like having one’s brain in a blender. –Paul GrahamGreat Hackers

With programmers, it’s especially hard. Productivity depends on being able to juggle a lot of little details in short term memory all at once. Any kind of interruption can cause these details to come crashing down. When you resume work, you can’t remember any of the details (like local variable names you were using, or where you were up to in implementing that search algorithm) and you have to keep looking these things up, which slows you down a lot until you get back up to speed. –Joel SpolskyWhere do These People Get Their (Unoriginal) Ideas?

It’s surprising, but bugs have a close relationship to number of lines of code - no matter whether the language is as low-level as assembler or high-level as Haskell (humorously,Norris’ number); is this because each line takes up a similar amount of working and short-term memory and there’s only so much memory to go around?11



It’s not all that obvious, but just about every productivity innovation in computing is about either cutting down on how much a programmer needs to know (eg. garbage collection), or making it easier for him to shuffle things in and out of his short term memory. Why are some commentators like Jeff Atwood so focused12 on having multiple monitors? For that matter, why are there real studies showing surprisingly large productivity boosts by simply adding a second monitor?13 It’s not like the person is any different afterwards. And arguably multiple or larger monitors come with damaging overheads14.

Or, why does Steve Yegge think touch-typing is one of the few skills programmers must know (along with reading)?15 Why is Unix guru Ken Thompson’s one regret not learning typing?16Typing hardly seems very important - it’s what you say, not how you say it. The compiler doesn’t care if you typed the source code in at 30WPM or 120WPM, after all.

The thing is, multiple monitors, touch-typing, speed-reading17 - they’re all about making the external world part of your mind. What’s the real difference between having a type signaturein your short-term memory or prominently displayed in your second monitor? What’s thereal difference between writing a comment in your mind or touch-typing it as fast as you create it?

I love being able to type that without looking! It’s empowering, being able to type almost as fast as you can think. Why would you want it any other way?

The thing is, multiple monitors, touch-typing, speed-reading17 - they’re all about making the external world part of your mind. What’s the real difference between having a type signaturein your short-term memory or prominently displayed in your second monitor? What’s thereal difference between writing a comment in your mind or touch-typing it as fast as you create it?

Just some speed. Just some time. And the more visible that type signature is, the faster you can type out that comment, the larger your memorygets. And the larger your memory is, the more intelligent/productive you can be. (Think of this as the Extended Mind thesis as applied to programming!) Great programmers often1819 talk vaguely about keeping a system in your head orhaving a model, and hate distractions20, saying they destroy one’s carefully developed thoughts; I think what they are talking about is trying to store all the relevant details inside their short-term or working memory. Learning programming has a correlation with WM.21 (Once you start looking, you see this everywhere. Games, for example.22) Or in bug rates - WM has been proposed as the reason why small or large chunks of programs have more proportional errors than medium sized chunks23. It remains to be seen whether programming tools designed with an eye to memory will be helpful, though.

But as great as things like garbage collection & touch-typing & multiple monitors are (I am a fan & user of the foregoing), they are still imperfect substitutes. Wouldn’t it be better if one could just improve one’s short-term/working memory directly? It might be more effective, and certainly would be more portable!

Indeed, the general history of attempts to increase IQ in any children or adults remains essentially what it was when Arthur Jensen wrote his 1969 paper How Much Can We Boost IQ and Scholastic Achievement? - a history of failure. The exceptions prove the rule by either applying to narrow groups with specific deficits or work only before birth, like iodization. (See also Algernon’s Law: if there were an easy fitness-increasing way to make us smarter, evolution would have already used it.)



Unfortunately, in general, IQ/g and memory don’t seem to be trainable. Many apparent effects are swamped by exercise or nutrition or by simple practice. And when practice does result in gains on tasks or expensive games24, said benefits often do not transfer; many popular brain games & exercises fail this criterion or at least have not been shown to transfer252627, even terribly brainy exercises like chess or memory competitions28Catch-22summed it up:

Shooting skeet eight hours a month was excellent training for them. It trained them to shoot skeet.

But hope springs eternal, and there are possible exceptions. The one this FAQ focuses on is Dual N-back, and it’s a variant on an old working-memory test.

One of the nice things about N-back is that while it may or may not improve your IQ, it may help you in other ways. WM training helps alcoholics reduce their consumption29 and increases patience in recovering stimulant addicts (cocaine & methamphetamine)30. The self-discipline or willpower of students correlates better with grades than even IQ31, WMcorrelates with grades and lower behavioral problems32 & WM out-predicts grades 6 years later in 5-year olds & 2 years later in older children33. WM training has been shown to help children with ADHD34 and also preschoolers without ADHD35Lucas 2008 found behavior improvements at a summer camp. Another intervention using a miscellany of reasoninggames with young (7-9 years old) poor children found a Forwards Digit Span (but not Backwards) and IQ gains, with no gain to the subjects playing games requiring rapid visual detection and rapid motor responses36, but it’s worth remembering that IQ scores are unreliable in childhood37 or perhaps, as an adolescent brain imaging study indicates38, they simply are much more malleable at that point. (WM training in teenagers doesn’t seem much studied but given their issues, may help; see Beautiful Brains or The Trouble With Teens.)

There are many kinds of WM training. One review worth reading is Does working memory training work? The promise and challenges of enhancing cognition by training working memory (Morrison & Chein 2011); Is Working Memory Training Effective? (Shipstead, Redick, & Engle 2012) discusses the multiple methodological difficulties of designing WM training experiments (at least, they are difficult if you want to show genuine improvements which transfer to non-WM skills).

In this version, called dual N-back (to distinguish it from the classic single N-back), one is still playing a turn-based game. In the Brain Workshop version, you are presented with a 3x3 grid in which every turn, a block appears in 1 of the 9 spaces and a letter is spoken aloud. (There are any number of variants: the NATO phonetic alphabet, piano keys, etc. And Brain Workshop has any number of modes, like Arithmetic N-back or Quintuple N-back.)



The original N-back test simply asked that you remember a single stream of letters, and signal if any letters were precisely, say, 2 positions apart. A S S R wouldn’t merit a signal, but A S A R would since there are A characters exactly 2 positions away from each other. The program would give you another letter, you would signal or not, and so on. This is simple enough once you understand it, but is a little hard to explain. It may be best to read the Brain Workshop tutorial, or watch a video.


In 2003, Susan Jaeggi and her team began fMRI studies using a variant of N-back which tried to increase the burden on each turn - remembering multiple things instead of just 1. The abstract describes the reason why:

With reference to single tasks, activation in the prefrontal cortex (PFC) commonly increases with incremental memory load, whereas for dual tasks it has been hypothesized previously that activity in the PFC decreases in the face of excessive processing demands, i.e., if the capacity of the working memory’s central executive system is exceeded. However, our results show that during both single and dual tasks, prefrontal activation increases continuously as a function of memory load. An increase of prefrontal activation was observed in the dual tasks even though processing demands were excessive in the case of the most difficult condition, as indicated by behavioral accuracy measures. The hypothesis concerning the decrease in prefrontal activation could not be supported and was discussed in terms of motivation factors.39


In 1-back, the task is to correctly answer whether the letter is the same as the previous round, and whether the position is the same as the previous round. It can be both, making 4 possible responses (position, sound, position+sound, & neither).

This stresses working memory since you need to keep in mind 4 things simultaneously: the position and letter of the previous turn, and the position and letter of the current turn (so you can compare the current letter with the old letter and the current position with the old position). Then on the next turn you need to immediately forget the old position & letter (which are now useless) and remember the new position and letter. So you are constantly remembering and forgetting and comparing.



But 1-back is pretty easy. The turns come fast enough that you could easily keep the letters in your phonological loop and lighten the load on your working memory. Indeed, after 10 rounds or so of 1-back, I mastered it - I now get 100%, unless I forget for a second that it’s 1-back and not 2-back (or I simply lose my concentration completely). Most people find 1-back very easy to learn, although a bit challenging at first since the pressure is constant (games and tests usually have some slack or rest periods).

The next step up is a doozy: 2-back. In 2-back, you do the same thing as 1-back but as the name suggests, you are instead matching against 2 turns ago. So before you would be looking for repeated letters - AA - but now you need to look for separated letters - ABA. And of course, you can’t forget so quickly, since you still need to match against something likeABABA.

2-back stresses your working memory even more, as now you are remembering 6 things, not 4: 2 turns ago, the previous turn, and the current turn - all of which have 2 salient features. At 6 items, we’re also in the mid-range of estimates fornormal working memory capacity:

And even if there are only a few things to remember, the number of responses you have to choose between go up exponentially with how many modes there are, so Triple N-back has not ⅓ more possible responses than Dual N-back, but more than twice as many: if m is the number of modes, then the number of possible responses is 2m-1 (the -1 is there because one can nothing in every mode, but that’s boring and requires no choice or thought), so DNB has 3 possible responses40, while TNB has 741, Quadruple N-back 1542, and Quintuple N-back 3143!

Working memory is generally considered to have limited capacity. The earliest quantification of the capacity limit associated with short-term memory was the magical number seven introduced by Miller (1956). He noticed that the memory span of young adults was around seven elements, called chunks, regardless whether the elements were digits, letters, words, or other units. Later research revealed that span does depend on the category of chunks used (e.g., span is around seven for digits, around six for letters, and around five for words), and even on features of the chunks within a category….Several other factors also affect a person’s measured span, and therefore it is difficult to pin down the capacity of short-term or working memory to a number of chunks. Nonetheless, Cowan (2001) has proposed that working memory has a capacity of about four chunks in young adults (and fewer in children and old adults).

Worse, the temporal gap between elements is deeply confusing. It’s particularly bad when there’s repetition involved - if the same square is selected twice with the same letter, you might wind up forgetting both!

So 2-back is where the challenge first really manifests. After about 20 games I started to get the hang of it. (It helped to play a few games focusing only on one of the stimuli, like the letters; this helps you get used to the reaching back of 2-back.)



Have I seen any benefits yet? Not really. Thus far it’s like meditation: I haven’t seen any specific improvements, but it’s been interesting just to explore concentration - I’ve learned that my ability to focus is much less than I thought it was! It is very sobering to get 30% scores on something as trivial as 1-back and strain to reach D2B, and even more sobering to score 60% and minutes later score 20%. Besides the intrinsic interest of changing one’s brain through a simple exercise - meditation is equally interesting for how one’s mind refuses to cooperate with the simple work of meditating, and I understand that there are even vivid hallucinations at the higher levels - N-back might function as a kind of mental calisthenics. Few people exercise and stretch because they find the activities intrinsically valuable, but they serve to further some other goal; some people jog because they just enjoy running, but many more jog so they can play soccer better or live longer. I am young, and it’s good to explore these sorts of calisthenics while one has a long life ahead of one; then one can reap the most benefits.


N-back training is sometimes referred to simply as N-backing, and participants in such training are called N-backers. Almost everyone uses the Free, featureful & portable program Brain Workshop, abbreviated BW (but see the software section for alternatives).

There are many variants of N-back training. A 3-letter acronym ending in B specifies one of the possibilities. For example,D2B and D6B both refer to a dual N-back task, but in the former the depth of recall is 2 turns, while in the latter one must remember back 6 rounds; the D, for Dual, indicates that each round presents 2 stimuli (usually the position of the square, and a spoken letter).

But one can add further stimuli: spoken letter, position of square, and color of square. That would be Triple N-back, and so one might speak of how one is doing on T4B.

One can go further. Spoken letter, position, color, and geometric shape. This would be Quad N-back, so one might discuss one’s performance on Q3B. (It’s unclear how to compare the various modes, but it seems to be much harder to go from D2B to T3B than to go from D2B to D3B.)

Past QNB, there is Pentuple N-back (PNB) which was added in Brain Workshop 4.7 (video demonstration). The 5th modality is added by a second audio channel - that is, now sounds are in stereo.

Other abbreviations are in common use: WM for working memoryGf for fluid intelligence, and g for the general intelligence factor measured by IQ tests.


Notes from the author


To those whose time is limited: you may wish to stop reading here. If you seek to improve your life, and want the greatestbang for the buck, you are well-advised to look elsewhere.

Meditation, for example, is easier, faster, and ultra-portable. Typing training will directly improve your facility with a computer, a valuable skill for this modern world. Spaced repetition memorization techniques offer unparalleled advantages to students. Nootropics are the epitome of ease (just swallow!), and their effects are much more easily assessed - one can even run double-blind experiments on oneself, impossible with dual N-back. Other supplements like melatonin can deliver benefits incommensurable with DNB - what is the cognitive value of another number in working memory thanks to DNB compared to a good night’s sleep thanks to melatonin? Modest changes to one’s diet and environs can fundamentally improve one’s well-being. Even basic training in reading, with the crudest tachistoscope techniques, can pay large dividends if one is below a basic level of reading like 200WPM & still subvocalizing. And all of these can start paying off immediately.

DNB, on the other hand, requires a minimum of 15 hours before one can expect genuine somatic improvements. The task itself is unproven - the Jaeggi studies are suggestive, not definitive (and there are contrary results). Programs for DNB training rely essentially on guesswork as they explore the large design-space; there are no data on what features are essential, what sort of presentation optimal, or even how long or when to train for. The task itself is unenjoyable. It can be wearying, difficult & embarrassing. It can be one too many daily tasks, a straw which breaks the camel’s back, and a distraction from whatever activity has the greatest marginal utility for one44 and one ought to be doing instead.

So why then do I persevere with DNB?

I do it because I find it fascinating. Fascinating that WM can be so large a part of IQ; fascinating that it can be increased by an apparently trivial exercise. I’m fascinated that there are measurable gross changes in brain activity & chemistry & composition45 - that the effects are not purely mental or placebo. I’m fascinated by how the sequence of positions and letters can at some times appear in my mind with boundless lucidity, yet at other times I grope confused in a mental murk unsure of even what the last position/letter was - even though I can rise from my computer and go about normal activities normally; or with how time can stretch and compress during N-backing46. I’m fascinated by how a single increase in n-level can render the task nightmarishly difficult when I just finished n-1 at 90 or 100%. I’m fascinated by how saccading, another apparently trivial exercise, can reliably boost my score by 10 or 20%, and how my mind seems to be fagged after just a few rounds but recovers within minutes. I’m equally fascinated by the large literature on WM: what it is, what’s it good for, how it can be manipulated, etc.

I do not think that DNB is terribly practical - but interesting? Very.



BrianLook, you’ve got it all wrong! You don’t need to follow me, You don’t need to follow anybody! You’ve got to think for your selves! You’re all individuals!

The CrowdYes! We’re all individuals!47


This FAQ is almost solely my own work. I’ve striven to make it fair, to incorporate most of the relevant research, and to not omit things. But inevitably I will have made errors or important omissions. You must read this skeptically.

You must read this skeptically also because the N-back community formed around the mailing list is a community. That means it is prone to all the biases and issues of a community. One would expect a community formed around a technique or practice to be made up only of people who find value in it; any material (like this FAQ or included testimonials) is automatically suspect due to biases such as the commitment or sunk cost bias. Imagine if scientists published only papers which showed new results, and no papers reporting failure to replicate! Why would any N-backer hang around who had discovered that DNB was not useful or a fraud? Certainly the fans would not thank him. (Eliezer Yudkowsky has an excellent essay called Evaporative Cooling of Group Beliefs on this topic; fortunately, the damage caused by a dual n-back would be limited, in comparison to some other examples of evaporative cooling like pro-ana or mind-control victims.)

Finally, you must read skeptically because this is about psychology. Psychology is notoriously for being one of the hardest scientific fields to get solid results in, because everybody is WEIRD and different. As one of my professors joked, if you have 2 psychology papers reporting he same result, one of them is wrong; there are many issues with taking a psychology study at face value (to which I have devoted an appendix, Flaws in mainstream science (and psychology)). It’s very tempting to engage in Generalizing From One Example but you mustn’t. Everybody is different; your positive (or negative) result could be due to a placebo effect, it could be thanks to that recent shift in your sleep schedule for the better48, or that nap you took49, it could be the exercise you’re getting50, it could be a mild seasonal depression lifting (or setting in), it could be acalcium or zinc51 or iodine deficiencyhypoglycemia52, variation in motivation etc.


N-back training


Most users seem to go for one long N-back session, pointing out that exercises one’s focus. Others do one session in the morning and one in the evening so they can focus better on each one. There is some scientific support for the idea that evening sessions are better than morning sessions, though; see Kuriyama 2008 on how practice before bedtime was more effective than after waking up.

If you break up sessions into more than 2, you’re probably wasting time due to overhead, and may not be getting enough exercise in each session to really strain yourself like you need to.



The simplest mental strategy, and perhaps the most common, is to mentally think of a list, and forget the last one each round, remembering the newest in its place. This begins to break down on higher levels - if one is repeating the list mentally, the repetition can just take too long.

Surcer writes up a list of strategies for different levels in his My System, let’s share strategies thread.



People frequently ask and discuss whether they should use some sort of strategy, and if so, what.

A number of N-backers adopt an intuition strategy. Rather than explicitly rehearsing sequences of letters (f-up, h-middle; f-up, h-middle; g-down, f-up…), they simply think very hard and wait for a feeling that they should press a (audio match), or l (location match). Some, like SwedishChef can be quite vociferous about it:

The challenges are in helping people understand that dual-n-back is NOT about remembering n number of visual and auditory stimuli. It’s about developing a new mental process that intuitively recognizes when it has seen or heard a stimuli n times ago.

Initially, most students of dual n-back want to remember n items as fast as they can so they can conquer the dual-n-back hill. They use their own already developed techniques to help them remember. They may try to hold the images in their head mentally and review them every time a new image is added and say the sounds out loud and review the sounds every time a new sound is added. This is NOT what we want. We want the brain to learn a new process that intuitively recognizes if an item and sound was shown 3 back or 4 back. It’s sort of like playing a new type of musical instrument.

I’ve helped some students on the site try to understand this. It’s not about how much you can remember, it’s about learning a new process. In theory, this new process translates into a better working memory, which helps you make connections better and faster.

Other N-backers think that intuition can’t work, or at least doesn’t very well:

Few N-backers have systematically tracked intuitive versus strategic playing; DarkAlrx reports on his blog the results of his experiment, and while he considers them positive, others find them inconclusive, or like Pheonexia, even unfavorable for the intuitive approach:

Jaeggi herself was more moderate in ~2008:


I don’t believe that much in the intuitive method. I mean, sure, you can intuitively remember you heard the same letter or saw the square at the same position a few times ago, but I fail to see how you can feel it was exactly 6 or 7 times ago without some kind of active remembering. –Gaël DEEST

I totally agree with Gaël about the intuitive method not holding much water…For me a lot of times the intuitive method can be totally unreliable. You’ll be doing 5-back one game and a few games later your failing miserably at 3-back..your score all over the place. Plus, intuitive-wise, it’s best to play the same n-back level over and over because then you train your intuition…and that doesn’t seem right. –MikeM (same thread)

Looking at your graphs and the overall drop in your performance, I think it’s clear that intuitive doesn’t work. On your score sheet, the first picture, using the intuitive method over 38 days of TNB training in 44 days your average n-back increased by less than .25. You were performing much better before. With your neurogenesis experiment, your average n-back actually decreased.

I would NOT recommend you [train the visual and auditory task separately] if you want to train the dual-task (the one we used in our study). The reason is that the combination of both modalities is an entirely different task than doing both separately! If you do the task separately, I assume you use some rehearsal strategies, e.g. you repeat the letters or positions for yourself. In the dual-task version however, these strategies might be more difficult to apply (since you have to do 2 things simultaneously…), and that is exactly what we want… We don’t want to train strategies, we want to train processes. Processes that then might help you in the performance of other, non-trained tasks (and that is our ultimate goal). So, it is not important to reach a 7- or 8-back… It is important to fully focus your attention on the task as well as possible.

I can assure you, it is a very tough training regimen…. You can’t divert your attention even 1 second (I’m sure you have noticed…). But eventually, you will see that you get better at it and maybe you notice that you are better able to concentrate on certain things, to remember things more easily, etc. (hopefully).

(Unfortunately, doubt has been cast on this advice by the apparent effectiveness of single n-back in Jaeggi 2010. If single (visual/position) n-back is effective in increasing IQ, then maybe training just audio or just visual is actually a good idea.)

But it may make no difference. Even if you are engaged in a complex mnemonic-based strategy, you’re still working your memory. Strategies may not work; quoting from Jaeggi’s 2008 paper:

Even if they do, they may not be a good idea; quoting from Jaeggi 2010:

Hopefully even if a trick lets you jump from 3-back to 5-back, Brain Workshop will just keep escalating the difficulty until you are challenged again. It’s not the level you reach, but the work you do.

Jonathan Toomin writes:

This is reminiscent of sleep’s involvement in other forms of memory and cognitive change, and Kuriyama 2008.

But he cautions us that besides being a considerable time investment, it may only work for him:

Raman started DNB training, and in his first 30 days, he took breaks every 5 days or so, and was doing about 20-30 session each day and n-back wise I made good gains (from 2 to 7 touching 9 on the way).; he kept a journal on the mailing list about the experience with daily updates.


this is a question i am being asked a lot and unfortunately, i don’t really know whether i can help with that. i can only tell you what we tell (or rather not tell) our participants and what they tell us. so, first of all, we don’t tell people at all what strategy to use - it is up to them. thing is, there are some people that tell us what you describe above, i.e. some of them tell us that it works best if they don’t use a strategy at all and just let the squares/letters flow by. but of course, many participants also use more conscious strategies like rehearsing or grouping items together. but again - we let people chose their strategies themselves! ref

By this account, one reason for having obtained transfer between working memory and measures of Gf is that our training procedure may have facilitated the ability to control attention. This ability would come about because the constant updating of memory representations with the presentation of each new stimulus requires the engagement of mechanisms to shift attention. Also, our training task discourages the development of simple task-specific strategies that can proceed in the absence of controlled allocation of attention.

We also proposed that it is important that participants only minimally learn task-specific strategies in order to prevent specific skill acquisition. We think that besides the transfer to matrix reasoning, the improvement in the near transfer measure provides additional evidence that the participants trained on task-underlying processes rather than relying on material-specific strategies.


A matter of preference, although those in favor of disabling the visual feedback (SHOW_FEEDBACK = False) seem to be slightlymore vocal or numerous. Brain Twister apparently doesn’t give feedback. Jaeggi says:

the gaming literature also disagrees on this issue - there are different ways to think about this: whereas feedback after each trial gives you immediate feedback whether you did right or wrong, it can also be distracting as you are constantly monitoring (and evaluating) your performance. we decided that we wanted people to fully and maximally concentrate on the task itself and thus chose the approach to only give feedback at the end of the run. however, we have newer versions of the task for kids in which we give some sort of feedback (points) for each trial. thus - i can’t tell you what the optimal way is - i guess there are interindividual differences and preferences as well.

When I was doing visual psychophysics research, I heard from my labmates that this question has been investigated empirically (at least in the context of visual psychophysics), and that the consensus in the field is that using feedback reduces immediate performance but improves learning rates. I haven’t looked up the research to confirm their opinion, but it sounds plausible to me. I would also expect it to apply to Brain Workshop. The idea, as I see it, is that feedback reduces performance because, when you get an answer wrong and you know it, your brain goes into an introspective mode to analyze the reason for the error and (hopefully) correct it, but while in this mode your brain will be distracted from the task at hand and will be more likely to miss subsequent trials.


Focus harder. Play more. Sleep well, and eat healthily. Use natural lighting53. Space out practice. The less stressed you are, the better you can do.


Penner et al 2012

This study compared a high intensity working memory training (45 minutes, 4 times per week for 4 weeks) with a distributed training (45 minutes, 2 times per week for 8 weeks) in middle-aged, healthy adults…Our results indicate that the distributed training led to increased performance in all cognitive domains when compared to the high intensity training and the control group without training. The most significant differences revealed by interaction contrasts were found for verbal and visual working memory, verbal short-term memory and mental speed.


Curtis Warren has noticed that when he underwent a 4-day routine of practicing more than 4 hours a day, he jumped an entire level on even quad N-back54:

For example, over the past week I have been trying a new training routine. My goal was to increase my intelligence as quickly as possible. To that end, over the past 4 days I’ve done a total of roughly 360 sessions @ 2 seconds per trial (= ~360 minutes of training). I had to rest on Wednesday, and I’m resting again today (I only plan on doing about 40 trials today). But I intend to finish off the week by doing 100 sessions on Saturday and another 100 on Sunday. Or more, if I can manage it.

The point is, while I can say without a doubt that this schedule has been effective for me, it might not be effectivefor you. Are the benefits worth the amount of work needed? Will you even notice an improvement? Is this healthy? These are all factors which depend entirely upon the individual actually doing the training.

Alas, neither Raman nor Warren took an IQ or digit-span test before starting, so they can only report DNB level increases & subjective assessments.

The research does suggest that diminishing returns does not set in with training regimes of 10 or 15 minutes a day; for example, Nutley 2011 trained 4-year-olds in WM exercises, Gf (NVR) exercises, or both:

…These analyses took into account that the groups differed in the amount of training received, full dose for NVR or WM groups or half dose for the CB group (Table 3). Even though the pattern is not consistent across all tests (see Figure 2), this is interpreted as confirmation of the linear dose effect that was expected to be seen. Our results suggest that the amount of transfer to non-trained tasks within the trained construct was roughly proportionate to the amount of training on that construct. A similar finding, with transfer proportional to amount of training, was reported by Jaeggi et al. (2008). This has possible implications for the design of future cognitive training paradigms and suggests that the training should be intensive enough to lead to significant transfer and that training more than one construct does not entail any advantages in itself. The training effect presumably reaches asymptote, but where this occurs is for future studies to determine. It is probably important to ensure that participants spend enough time on each task in order to see clinically significant transfer, which may be difficult when increasing the number of tasks being trained. This may be one of the explanations for the lack of transfer seen in the Owen et al. study (2010) (training six tasks in 10 minutes).


Some people start n-backing with great vigor and rapidly ascend levels until suddenly they stop improving and panic, wondering if something is wrong with them. Not at all! Reaching a high level is a good thing, and if one does so in just a few weeks, all the more impressive since most members take much longer than, say, 2 weeks to reach good scores on D4B. In fact, if you look at the reports in the Group survey, most reports are of plateauing at D4B or D5B months in.

The crucial thing about N-back is just that you are stressing your working memory, that’s all. The actual level doesn’t matter very much, just whether you can barely manage it; it is somewhat like lifting weights, in that regard. From Jaeggi 2008:

Mailing list members report benefits even if they have plateaued at 3 or 4-back; see the benefits section.

The finding that the transfer to Gf remained even after taking the specific training effect into account seems to be counterintuitive, especially because the specific training effect is also related to training time. The reason for this capacity might be that participants with a very high level of n at the end of the training period may have developed very task specific strategies, which obviously boosts n-back performance, but may prevent transfer because these strategies remain too task-specific (5, 20). The averaged n-back level in the last session is therefore not critical to predicting a gain in Gf; rather, it seems that working at the capacity limit promotes transfer to Gf.

One commonly reported tactic to break a plateauing is to deliberately advance a level (or increase modalities), and practice hard on that extra difficult task, the idea being that this will spur adaptation and make one capable of the lower level.



Some people have wondered if not n-backing for a day/week/month or other extended period undoes all their hard work, and hence n-backing may not be useful in the long-term.

Multiple group members have pointed to long gaps in their training, sometimes multiple months up to a year, which did not change their scores significantly (immediately after the break, scores may dip a level or a few percentage points in accuracy, but quickly rises to the old level). Some members have ceased n-backing for 2 or 3 years, and found their scores dropped by only 2-4 levels - far from 1 or 2-back. (Pontus Granström, on the other hand, took a break for several months and fell for a long period from D8B-D9B to D6B-D7B; he speculates it might reflect a lack of motivation.) huhwhat/Nova fell 5 levels from D9B but recovered quickly:

This anecdotal evidence is supported by at least one WM-training letter, Chrabaszcz 2010:

Similarly, Dahlin 2008 found WM training gains which were durable over more than a year:

I’ve been training with n-back on and off, mostly off, for the past few years. I started about 3 years ago and was able to get up to 9-n back, but on average I would be doing around 6 or 7 n back. Then I took a break for a few years. Now after coming back, even though I have had my fair share of partying, boxing, light drugs, even polyphasic sleep, on my first few tries I was able to get back up to 5-6, and a week into it I am back at getting up to 9 n back.

Figure 1b illustrates the degree to which training transferred to an ostensibly different (and untrained) measure of verbal working memory compared to a no-contact control group. Not only did training significantly increase verbal working memory, but these gains persisted 3 months following the cessation of training!

The authors investigated immediate training gains, transfer effects, and 18-month maintenance after 5 weeks of computer-based training in updating of information in working memory in young and older subjects. Trained young and older adults improved significantly more than controls on the criterion task (letter memory), and these gains were maintained 18 months later. Transfer effects were in general limited and restricted to the young participants, who showed transfer to an untrained task that required updating (3-back)…


Some users have reported being able to go all the way up to 12-back; Ashirgo 


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