Four hours of concentration

As I’ve blogged about before, and mentioned again in my previous post, the great mathematician and physicist Henri Poincaré put in two hours of work in the morning and two in the evening.

Apparently this is a common pattern. Cal Newport mentions this in his interview with Todd Henry.

Now we also know that if you study absolute world class, best virtuoso violin players, none of them put in more than about four or so hours of practice in a day, because that’s the cognitive limit. And this limit actually shows up in a lot of different fields where people do intense training, that you really can’t do about more than four or so hours of this type of really mental strain.

And they often break this into two sessions, of two hours and then two hours. So there’s huge limits here. I think if you’re able to do three, maybe four hours of this sort of deep work in a typical day, you’re hitting basically the mental speed limit, the amount of concentration your brain is actually able to give.

He goes on to say that you may be able to work 15 hours a day processing email and doing other less demanding work, but nobody can sustain more than about four hours of intense concentration per day.

Update: The comments add examples of authors and physicists who had a similar work schedule.

Related post: Increasing your chances of entering flow

46 thoughts on “Four hours of concentration

  1. I disagree. You cannot do more than 4 hours on a long term basis. I have often had bursts of 15+ hours of intense concentration, just not on a predictable schedule.

    Yoga / meditation can help you make the most of the 4 hours and maybe extend it to 5 as well.

  2. Sincerely, 15 hours of intense concentration everyday is impossible.
    I think we are talking about hours per week, correct?
    But four is productive, when you can get intense concentration.

  3. I start my day early because I can get a days work done before the business day chatter even starts. Ideally, I’ll find another couple hours flow during the day. Anything significant, requiring full focus gets done before lunch, which I take at 11AM. The rest of the day is often administrivia. I’m not a night person. I prefer to get up even earlier if I need more time.

    One aspect of the effectiveness of those who can be at the top of their game with four hours/day of focus is that they focus on the right things during that time. Many people are less effective with more time because they work on things that don’t move the ball forward.

  4. Ericsson says in “The Role of Deliberate Practice” that lots of authors also did 4 hours:

    > The best data on sustained intellectual activity comes from financially independent authors. While completing a novel famous authors tend to write only for 4 hr during the morning, leaving the rest of the day for rest and recuperation ([Cowley, M. (Ed.). (1959). _Writers at work: The Paris review interviews_.]; [Plimpton, G.] (Ed.). (1977). _Writers at work: The Paris review. Interviews, second series_.]). Hence successful authors, who can control their work habits and are motivated to optimize their productivity, limit their most important intellectual activity to a fixed daily amount when working on projects requiring long periods of time to complete…Biographies report that famous scientists such as Charles Darwin, (Erasmus Darwin, 1888), Pavlov (Babkin, 1949), Hans Selye (Selye, 1964), and B.F. Skinner (Skinner, 1983) adhered to a rigid daily schedule where the first major activity of each morning involved writing for a couple of hours. In a large questionnaire study of science and engineering faculty, Kellogg (1986) found that writing on articles occurred most frequently before lunch and that limiting writing sessions to a duration of 1-2 hr was related to higher reported productivity…In this regard, it is particularly interesting to examine the way in which famous authors allocate their time. These authors often retreat when they are ready to write a book and make writing their sole purpose. Almost without exception, they tend to schedule 3-4 hr of writing every morning and to spend the rest of the day on walking, correspondence, napping, and other less demanding activities (Cowley, 1959; Plimpton, 1977).

  5. gwern: It’s interesting that the report you quoted came out in 1959. I expect it would have seemed more radical then than it does now.

    I read Stephen King’s “On Writing” a few years ago and I think he has something like the schedule you describe.

  6. @ksheth: I agree that concentration isn’t limited to 4hrs – I’ve had 16, 20 hour marathons of studying and of programming before – but within those marathons the vast majority of the work was done on “autopilot”. 4hrs sounds about right for the amount of time that I’m consciously engaged during such day-long flows.

  7. One of my advisors in graduate school, Martin Schwarzschild, told me exactly the same thing, about himself and about John Von Neumann.

  8. Pranav: Eight hours a day is about 2000 hours per year. At that rate, it would take five years to put in 10,000 hours. The question becomes how intense those 10,000 hours need to be. If you believe those 10,000 hours need to be “deliberate practice,” an idea often tossed about in the same context as the 10,000 rule, then this blog post would suggest you can’t become an expert in anything in five years. You’d need 10 years to put in enough four-hour days.

    But I don’t think the level of intensity that Gladwell, for example, has in mind is quite as intense as that described here. For example, Gladwell talks about the Beatles performing 8 hours a day for a total of 10,000 hours. Performing is not necessarily as intense as deliberate practice. Performing can be intense, such as a classical musician performing a virtuoso piece, but playing rock and roll in bars is not as intense. Not that it can’t be challenging, but it’s not a constant challenge.

  9. Dear Mr. Cook,

    It hardly happens that a blog post by you doesn’t make me stumble and rethink about topics / issues that I take for granted. Many thanks for this. I am one of the many faceless readers / admirers of your posts, even though many times I don’t understand much when some of these dive deep into mathematical theories, their applications and nuances! :-)

  10. I think Poincare had about the ideal schedule to maximize concentration over a long period of time, but I think there are other ideal schedules for other goals. In particular, if you have 10 hours to do something, and you start out rested and relaxed, I think you can concentrate pretty much constantly until the time limit, followed by being unfocused on the next two days. That is, you can trade off overall efficiency for a longer burst of concentration, potentially getting much more than 4 hours into a single 24-hour period.

  11. The five-hour gap between the two-hour sessions is interesting. I see the first two hour session as getting the mind going on some topic, setting up a background task in one’s subconscious mind. Then you pick up the results in your second two-hour session.

    I find that at my greatly advanced age (56) I am no longer capable of or interested in marathon hacking sessions. I find it much better to stop when I reach a boundary of some sort. (One advantage of age is being able to get to those boundaries much quicker than when I was younger.)

  12. man [comment #10]: That time period coincides with his [Charlie Parker's] early heroin usage. Perhaps in the short run, Parker was able to “cheat” the creative concentration limits. But we all know how that ended:

    “The coroner who performed his autopsy mistakenly estimated Parker’s 34-year-old body to be between 50 and 60 years of age”

    [I added a couple bits of context above. -- John]

  13. When I am solving a difficult (for me) problem, I have to wait for my unconscious to offer me an insight before I become inspired enough to elaborate on the new aha moment. At one point I puzzled on the meaning of context for a couple of years, before I realized that context is the limiting factor in understanding anything. It is also how we recycle personal meanings to generate creativity. So it becomes the key to understanding anything and everything. I also discovered from this single enlightenment, that our conceptual world models, which are contained in the beliefs we hold as true, either enable us or define the limits of what we can understand in the future.

    But all of that, had to wait for my unconscious to feed me suggestions about what the concept of context actually meant to me as I integrated new understandings into my total contextual world model.

    Oddly enough it seems too simple to have been all that important, but it was a key understanding for me. It enables amazing insight as I deal with writing, because it enables me to consider all contextual information that is necessary for a new idea to be offered to an audience.

    In fact it seems like my life has been about discovering things which the rest of the world seems to know already. I still delight in the AHA moments anyway.

  14. I think most video editors editing Hollywood films and TV shows, film music composers etc would disagree. These work on extremely tight deadlines, making 12-15 hour days. Sure not 100% concentrated all the time, but pretty much, and definitely more than 4 hours. I used to edit TV shows; definitely a minimum of 10 hrs of concentration a day, especially with a producer/director next to you, no time to quickly check some random blogs. That’s sure not as abstract as working in math, but keeping clips in your head and working with the quirks of a non-linear edit system and trying to tell a story within a fixed timeframe definitely needs concentration. I do agree that most of the solutions came while at lunch, driving home or showering, in other words, when the task wasn’t being executed at the desk.

  15. Really interesting idea!

    That said, I think applying such a specific rule to all of humanity doesn’t seem to make much sense, especially when we can only find 5 anecdotal examples across a crowd.

    Human focus is rare. It takes practice and dedication, and it is often no fun. Its much easier to believe that it is a myth, or that our primal nature is being circumvented by the trappings of modern society.

    What is really telling is that Cal Newport gives himself an out. “Did you do more than four hours of work? Well, of course, it was less demanding!” How do we know it was less demanding? We see if we could last past four hours!

    This sort of circular, magical thinking is kind of scary to me.

  16. I wrote a book a couple of years ago and experimented explicitly with different times of day, different length writing sessions, and so on. While I could do occasional bursts of above-average productivity, by the time all 100,000 words were written, my records showed that when it came to working consistently and establishing a rhythm, I would average about 4 hours of writing a day, producing roughly 400 words per hour.

    I would love to find a way to “up” that limit!

  17. Nonsense. I used to work 16 hour days straight for decades. Without food. Without a bathroom break. Never had a congnitive or strain problem.

    Ever.

    How’d I do it? 100 pushups every other night.

    if you are in top, fantastic shape, nothing bothers you and your mind’s like a steel trap. And you’ve got so much excess energy, stress is irrelevant.

    If you are out of shape, well then it’s a different story.

  18. I worked as an attorney for big law firms for about 10 years. We were expected to bill 8 or more hours per day. (To honestly bill 8 hours, you’ve really got to work about 10 to 12 hours because not even the most efficient attorney can bill 100% of his time.)

    I used to tell my colleagues all of the time that I really had about 6 hours of quality working time per day – about 3 hours in the morning before lunch, and about 3 hours in the afternoon – so this article rings very true to me.

  19. Probably the most glaring counter example is Paul Erdős who worked on several mathematical problems simultaneously for up to 19 hours a day and is the most prolific mathematician of out time.

  20. I agree. I work as an office manager and have multiple “titles” on my shoulder that I’m accountable for. I am responsible for payroll, a/r, a/p, customer service, contract negotiation and schedule management, along with almost any task that needs to be done in this small company to keep us kicking. Although it’s impossible to avoid the e-mails, phone calls, and regular tasking throughout the day, I get almost all of my work done in the first few hours of the day, and when business is slow, sometimes complete a weekly workload in the early hours of the first couple days.

  21. Weltnetzerkunder: If I had data from a large, relevant, well-designed, randomized study to consult I’d rather do that. But that doesn’t exist and I doubt it ever will. Anecdotes are better than nothing. And the anecdotes, along with personal experience, suggest a couple things.

    First, you can get more done in blocks of concentrated effort. Most people concentrate for only minutes at a time. A block of two concentrated hours would be a huge increase. And there are breakthroughs you can make in two-hour sprints that you’ll never accomplish in scattered 10 minute intervals.

    Second, people who say they’re concentrating hard for 12 hours a day are probably not. They may be exaggerating, or they may be working at a lower intensity than this post describes.

    A lot of people honestly think they work longer and harder than they do. Others are aware that they’re really productive for maybe half their day and that they fill the rest of the day with fluff, either deliberately or by busywork forced on them.

    A bigger theme here is that industrial norms don’t apply well to mental work. If you’re working on an assembly line, one hour’s work is pretty much like another. But if you’re programming, for example, some hours are far more productive than others. Measuring intellectual output by the hour is problematic to say the least. It’s like measuring distance by time spent traveling, regardless of whether you’re walking, driving, or flying.

    Update: I’ve written a new blog post discussing whether randomized studies of productivity are even feasible.

  22. I’ve been thinking about this post, and one advantage of accepting the notion of four hours of hard concentration in a day is that you can feel satisfied after those four hours are completed.

    If you put pressure on yourself to produce eight hours of hard concentration every day, there will be a psychological tax or mental weight you feel from believing you consistently under-perform, which will make the time you do concentrate deeply even less effective.

  23. I’m not sure this 4 hour rule is hard and fast for everyone. I have auditory synesthisa, which means most things I hear gets converted into a 3D textured/colored object in a passive but constant manner.

    This means that, in a noisy environment, I’m basically being distracted all the time, although in reality because I’ve grown up with this I’ve become able to totally shut it out and just focus. Effectively every moment of every day in a noisy room I’m training myself to focus on a task in hand, and this has had no negative consequences to my academic or every day functional ability, thankfully.

    However, what it has done is allowed me to focus for much longer than normal people can. I can comfortably sit and stay totally focused for 6-8 hours, and with short breaks to get water/food I have no trouble working in a highly productive manner for 10-15 hours at a time.

    This has allowed me to achieve a number of things I suspect my relatively modest intellect would otherwise prohibit, and is certainly not the norm. However, I only realized this wasn’t the case for everyone in my very late teens (imagine discovering that, actually, the entire world is colorblind and no-one ever though to discuss it) so if some people say they are able to focus for extended periods of time don’t necessarily dismiss them out of hand.

  24. I remember G.H. Hardy mentioning in Apology of a Mathematician that he only worked in the mornings.

  25. Hi,
    I practice also the fours hours concentration tip, but two hours the monday, and two hour the friday

  26. Depends on the directionality of the “task” – native eastern yogis and seers routinely engage in weeks and months of intense concentration – only it is internally focused , not on external human invented tasks like music,art,math etc.
    These are tasks , skills of adhyatma-vidya , from the sanskrit , loosely translated in English as the inner sciences. So basically, anybody can do it – if one wants to.

  27. Probably the most glaring counter example is Paul Erdős who worked on several mathematical problems simultaneously for up to 19 hours a day and is the most prolific mathematician of out time.

    To elaborate, Erdős was continuously on amphetamines for about 25 years. It may well be that you can do things to your body and mind to get more than 4 hours’ full concentration in a day. Investigate with caution.

  28. Kind of disagree.
    Just like everything else human, you can train to reach higher limits. Through personal experimentation, martial arts (mostly boxing), yoga, healthy eating, and mediation contribute greatly to increase my concentration and cognitive abilities… meaning if I’m on track I am killin it, but when my routine falters, my higher level of relative cognitive abilities goes down.

  29. One thing is sure for me. If I have a limited time to do something – say 1 hour – then I can usually make much better use of it than if it was an hour out of 5. And I have learned that imposing some self-contract (like “now I will do task X for 30 minutes”) can work wonders.

  30. Possibly true, but I spent years being able to ‘zone’ for 13-17 hours at a time. Absolute, intense focus on incredibly challenging power modeling analytics and programming. A mild concussion 16 months ago absolutely destroyed that, though. Now, an hour is an achievement.

Comments are closed.