How many different subjects should you try to learn at once? It’s obviously not impossible to learn more than one thing at a time—in school you often have to learn many different subjects simultaneously. Is there a compelling reason to stick to learning only one thing? Or will you learn more if you try to learn different things concurrently?
I don’t think there’s a clear-cut answer to this question, but it is one I’ve given a lot of thought. In this essay, I’ll try to explain what I think the compelling reasons are for learning things one at a time and in parallel, and then suggest some different strategies that cope with both.
The Case for Focused Learning
The case for focused learning, in my mind, doesn’t really have much to do with learning at all. Instead, I see the benefits of focusing on a single learning project as the same benefits for doing a limited number of any kinds of projects—learning, self-improvement, work, etc.—simultaneously.
Working on a project that you’ve planned yourself is complicated. You have to organize your efforts over many days or weeks to get it done. You need to juggle it with your background responsibilities of work and home. For self-started projects, it’s very easy for them to fade into the backburner of non-urgent tasks.
Having more projects increases this mental overhead, and makes coordinating your efforts on completing them much more complicated. Have one project? Easy, just work on it when you have time in your schedule. Have six projects? Just figuring out which you should work on can be a chore, nevermind doing the actual work.
Another pattern I’ve noticed when dealing with multiple projects is that we tend to push them forward when that’s easy to do. Unfortunately, learning new things is often very frustrating. So precisely when we need to be applying more effort to get over those humps is when we pull back.
By focusing your learning, it’s easier to push forward even when projects get difficult because you’ve committed yourself to not working on something else until you complete it.
Although the MIT Challenge  certainly could have been set up as a side activity pursued over a decade, it’s not clear to me I would have pushed through some of the hardest times if there were other, easier, goals in competition for my attention.
The simple case for focused learning is the same reason you focus with anything—to avoid crowding out your attention with things that are easier to to, but less important.
The Case for Parallel Learning Goals
Despite the advantages of focusing for getting projects finished, there are a number of compelling reasons from cognitive psychology to at least consider running learning goals in parallel.
The first is the spacing effect . The evidence here is very robust: we learn things better when we don’t cram it into a short period of time. Learning something spread over multiple days will produce longer, stronger memories, than learning something over a long burst on one day.
The reasons for this are not entirely understood yet. One of the reasons might be because of memory consolidation. That cramming too many repetitions of an concept in a single studying session may only result in a single act of consolidation, so the extra repetitions are wasteful. Another reason might be because learning is stronger when you’re switching frames or contexts—having to “boot” the information, so to speak, makes the memory more robust than thinking about it when you’ve just been thinking about it recently.
The spacing effect definitely strikes a blow against intense projects like the MIT Challenge. Although I did work to mitigate these problems later on, by running multiple classes in parallel, I doubt I was as successful as I could have been having learned over a longer timeframe.
Another, somewhat less robust effect is called interleaving . This is where you switch between different subjects to increase your amount learned. So in one day you’d study a bit of biology, chemistry, physics and philosophy, instead of splitting them up.
Interleaving may work by the same principle of spacing—that switching frames improves learning, or it may work from an entirely different mechanism. While spacing argues indirectly for parallel learning goals, interleaving argues for it quite directly.
The simple case for parallel learning goals is that you might learn more efficiently if you spread your studying out and switch between learning tasks.
What Should You Do? Examining Learning Structures
A learning structure is what I call an overall strategy to learning something. One of these structures I’ve already mentioned—setting up a project. A project structure involves commitment, planning and usually few or zero other competing projects.
However, that’s not the only way to learn things and there are other structures that also work. A habitual structure works by making the studying activity a habit—something you do regularly every week consistently. With a habitual structure you can manage a lot more learning goals in parallel.
A third structure, might be a casual structure—where you learn something when you have interest in it. This requires the least organization and is the default structure for most people, but sometimes it’s a good one to use if your interest is high, frustration is low and you want to minimize the stress of learning.
So how do you decide whether to learn via a project, habits or more casually? I use all three in my own learning efforts. The question to me is simply which aligns best with your goals and how do you offset its weaknesses.
Project Structure: Strengths and Weaknesses
The strength of the project structure is that it maximizes focus. This means it’s far easier to work on learning projects that are particularly difficult, frustrating or intense. It’s also easier to make progress in a timely fashion. While habits and casual structures are in it for the long haul, a project can make progress quickly which might be nice if you have some deadline (say an exam or job interview) when you want the skill to be ready before.
The weakness of projects is that you can’t do too many at once, maybe no more than one. This means you have to be selective about what you intend to learn (not always a bad thing), and you can’t benefit as much from spacing or interleaving as you might with another structure.
I’ve found there’s a couple ways to mitigate these weaknesses while still sticking with the project structure:
- Use short projects. If you rotate between shorter projects, you can make progress on multiple goals over a longer period of time. The Year Without English  used a project structure, but we ended up learning four languages in one year, quite a diverse set of goals.
- Use within-project spacing and interleaving. This means doing spaced review of things you’ve already learned within the project and switching between subtopics to study. I partially used this during the MIT Challenge and it offset some of the effects of cramming.
- Follow up a project with habits. A project can get you a lot of distance with a learning goal particularly fast. Once you’re done, however, you might want to switch to a habit structure to maintain what you’ve learned. That way you can get benefits from spacing in holding the knowledge in place.
Habitual Structure: Strengths and Weaknesses
The strength of a habitual structure is that you can get the increased efficiency due to spacing and interleaving, and you can learn multiple things simultaneously. Habits also force you to be patient with learning new skills, which can alleviate frustration by switching the task from being results-oriented to process-oriented.
The big weakness of habits is that if you hit large bouts of frustration or complexity, they can get completely derailed. Anyone who has been on vacation for awhile and seen their exercising habit fall apart can attest to that.
My reason for not using this structure exclusively is that sometimes there are learning goals which are too difficult or frustrating to make for smooth habits. You might be able to do flashcard review as a habit, but speaking a new language for the first time is often so frustrating it doesn’t benefit well from only receiving a fraction of your attention. Similarly, doing hard calculus problems isn’t something you relish jumping into when you’ve never done it before.
Here’s some thoughts on mitigating these weaknesses while still sticking to a habitual structure:
- Identify rough patches and reinforce those spots. This means when you know something will be frustrating, you give it your priority for a certain period of time and then lay off again when things get easier. This requires some intuition, but it effectively temporarily turns your habit into a project and then releases it when you can learn more smoothly again.
- Focus on input not results. If your habits are set around investing a particular amount of time doing a particular learning activity, regardless of how much progress you make, this can reduce some of the frustration.
- Run a mini-project to make strides through rough patches. This was what I did with my Portrait Drawing Challenge . I have been working on art as a casual learning process for over a year, but faces were giving me a lot of frustration and I wanted to improve them, so I switched gears temporarily. Now I’m back to the casual approach again.
Casual Structure: Strengths and Weaknesses
The strength of a casual structure is that it doesn’t require much willpower. You just let your interest level decide what you want to learn. This means you can learn many things at the same time.
The downside is that your progress will be heavily dependent on your motivation and can be easily derailed by frustrations. If your interest is really high and the subject is relatively smooth, then this might not be an issue.
I hesitate to talk about this structure because it’s a default approach for so many people. But that doesn’t mean you should avoid it completely. I’m making slow but steady progress on my cognitive science challenge , treating it mostly as a casual learning activity. The reason is that reading books is fairly enjoyable, and if a book gets too dense or boring, I switch books to keep my interest engaged.
Seeing as the casual approach to learning works when interest is greater than frustration, the key to avoiding its weaknesses is to note when this is no longer the case. If you start feeling like learning is a chore, you may want to either suspend learning that subject for a while or switch it to a project to push past the obstacle.
Casual learning also suffers because there isn’t an explicit set of priorities. While things that are more important tend to become more interesting, this isn’t always the case. So a casual approach sometimes has you learning more interesting things at the expense of more important things. Again, the solution here is to recognize when this is happening and switch to a more rigorous structure as needed.
Unfortunately I can’t offer an easy conclusion that learning should always be done with focus or in parallel. Instead, I think these are both valid strategies which work well in different cases for different goals.
Think about what you’re trying to learn right now. Are you trying to learn something important that is difficult enough to require focus? Try a project. Or are you trying to learn multiple things out of interest but often forget to work on them? Try establishing them as habits. Of course some things will inevitably just be learned casually, and perhaps that’s how they should remain!
Write in the comments what things you’re trying to learn right now and make a decision about whether you want to focus on them as a project, habits or just learn them casually. It’s okay to admit that something you want to learn requires a project but you can’t pursue it right now. At least being aware of that can bring the situation into clarity.