Desirable Difficulties: Why Making Your Studying Harder Actually Helps You Learn More

You just spent an hour re-reading your notes. The material feels familiar. You close your laptop feeling pretty good about tomorrow's exam. Then the test hits and you can't remember half of it.

What happened? You fell for one of the biggest traps in studying: you confused "feeling easy" with "actually learning." And you're not alone. Most students pick the study methods that feel smooth and comfortable, which are exactly the ones that don't stick.

UCLA psychologist Robert Bjork spent decades studying this problem. In 1994, he gave it a name: desirable difficulties. The idea is simple but uncomfortable. The study techniques that feel the hardest and most frustrating are usually the ones that produce the best long-term learning.

What Are Desirable Difficulties?

A desirable difficulty is any learning condition that makes studying feel harder in the moment but leads to stronger, more durable memory over time. Bjork's key insight was that there's a difference between performance and learning. Performance is how well you do right now. Learning is how well you remember next week, next month, or on exam day.

The problem? Easy study methods boost performance but barely touch learning. Hard study methods tank your immediate performance but build the kind of memory that actually lasts.

Think of it like working out. Lifting a weight that's too light feels great, but it doesn't build muscle. You need the struggle. Your brain works the same way. When retrieval feels effortful, when you have to really work to pull an answer from memory, that struggle strengthens the neural pathways that store that information.

Bjork and his wife Elizabeth Bjork formalized this with their "new theory of disuse" in 1992. They argued that every memory has two strengths: storage strength (how deeply it's encoded) and retrieval strength (how easily you can access it right now). Here's the counterintuitive part: when retrieval strength is high, practice does almost nothing for storage strength. But when retrieval strength is low, when you've partially forgotten something and have to work to retrieve it, successful retrieval massively increases both strengths.

That's why cramming works for tomorrow but fails for next week. And it's why the techniques below feel terrible but work brilliantly.

The Four Main Desirable Difficulties

Bjork identified several specific techniques that qualify as desirable difficulties. If you've been reading this blog, you'll recognize most of them. What you might not have realized is that they all work for the same reason: they make your brain work harder during study, which builds stronger memories.

1. Spacing your study sessions

Spacing means spreading your study sessions out over time instead of cramming everything into one marathon session. It feels less efficient because you forget some material between sessions and have to re-learn it. But that re-learning is the whole point. Each time you retrieve partially forgotten information, you strengthen it far more than if you'd just reviewed it while it was still fresh.

A major review by Cepeda and colleagues analyzed 254 studies on spacing and found it consistently outperformed massed practice for long-term retention. Spaced repetition is one of the most powerful study techniques that exists, and it works precisely because forgetting a little between sessions creates the desirable difficulty your brain needs.

2. Testing yourself instead of re-reading

Re-reading your notes feels productive. You recognize the material, it flows easily, and you feel confident. But recognition is not recall. The real test of learning is whether you can pull information from memory without looking at it.

A landmark 2008 study by Karpicke and Roediger found that repeated testing produced significantly better long-term recall than repeated studying, even when students felt like studying was more effective. The students who tested themselves didn't feel like they were learning more. They were. This is the testing effect in action, and it's a textbook desirable difficulty.

3. Interleaving different topics

Most students study one topic completely before moving on to the next. That's called blocked practice, and it feels organized and logical. Interleaved practice is the opposite: you mix different types of problems or topics together in the same session.

It feels messy. You'll make more mistakes during practice. But a 2014 classroom study by Rohrer and colleagues found that 7th graders who used interleaved math practice scored 72% on a delayed test, compared to just 38% for students who used traditional blocked practice. That's nearly double the performance, from a technique that felt worse while they were doing it.

4. Generating answers before being told

Instead of reading the answer, try generating it yourself first, even if you get it wrong. This is called the generation effect, and research going back to Slamecka and Graf in 1978 shows that information you actively produce is remembered better than information you passively receive.

This is why active recall works so well. When you close your notes and try to write down everything you remember, you're generating answers from scratch. The effort of production is the difficulty that makes it desirable.

Why Do Students Avoid These Techniques?

Here's the frustrating part. Even when students know about these techniques, many still default to re-reading and cramming. Why?

Because desirable difficulties feel bad. When you space your sessions, you feel like you're forgetting everything. When you test yourself, you get answers wrong and it stings. When you interleave topics, you feel confused and disorganized. Your brain interprets that struggle as a sign that learning isn't working.

But that's exactly backward. Bjork calls this the "performance-learning distinction." Easy practice creates the illusion of competence. You feel like you know the material because it's familiar right now. But familiarity is not the same as the ability to recall something from scratch on exam day.

The students who score highest on exams are usually the ones whose study sessions felt the most uncomfortable. Not painful or confusing, but genuinely effortful.

How to Use Desirable Difficulties (Without Burning Out)

The word "desirable" matters here. Not all difficulties help learning. Reading a blurry textbook or studying in a noisy room just adds frustration without any memory benefit. A difficulty is only desirable if it triggers the deeper processing that strengthens long-term memory.

Here's how to apply this in practice:

Space your reviews. Don't re-read your notes the same day you wrote them. Wait until you've started to forget, then try to recall the material. That feeling of "I kind of remember this but not really" is the sweet spot. If you want a system for this, the forgetting curve explains exactly why timing your reviews matters.

Test yourself before you feel ready. Don't wait until you've "finished studying" to take a practice quiz. Take one early, when you know you'll get things wrong. The mistakes are part of the process. Tools like StudyLab can generate practice quizzes from your notes, turning passive material into the kind of active challenge your brain needs.

Mix your subjects. Instead of spending three hours on chemistry, try 45 minutes of chemistry, then 45 minutes of history, then back to chemistry. The switching feels disruptive, but it forces your brain to reload the correct strategies each time, which builds stronger and more flexible knowledge.

Expect the struggle. If studying feels effortless, you're probably not learning much. A certain amount of productive frustration is the signal that real encoding is happening. When you catch yourself thinking "this is hard," remind yourself that hard is exactly how it's supposed to feel.

When Difficulties Become Undesirable

One important caveat from Bjork and Bjork's 2011 follow-up work: difficulties are only desirable when the learner can actually succeed despite the challenge. If a task is so hard that you can't complete it at all, it stops being a desirable difficulty and just becomes overwhelming.

If you're completely lost in a subject, spacing and interleaving won't help much. You need to build some foundation first. Desirable difficulties work best when you already have a basic understanding and you're trying to deepen and strengthen it. They're the difference between building on a foundation and trying to build without one.

Frequently Asked Questions

What's the difference between desirable difficulties and just making studying harder?

A desirable difficulty triggers deeper mental processing, like retrieving information from memory, discriminating between problem types, or reconstructing partially forgotten material. Just making things harder (studying with distractions, using confusing materials) adds effort without triggering those deeper processes. The difficulty has to connect to how your brain actually stores and retrieves information.

Can I use desirable difficulties for any subject?

Yes, but the specific techniques work best for different types of material. Testing and spacing work across all subjects. Interleaving is especially effective for math and science, where you need to choose between different problem-solving strategies. The generation effect works well for anything where you can produce answers from memory, like vocabulary, concepts, or essay arguments.

How do I know if I'm doing it right?

If studying feels a little uncomfortable, you're probably on the right track. You should feel like you're working to retrieve information, not just recognizing it. Making mistakes during practice is normal and actually helpful. If studying feels completely effortless and smooth, that's a warning sign that you're doing the easy version, not the effective version.

Do desirable difficulties work for cramming?

Not really. Desirable difficulties are a long-term strategy. The whole point is that you're trading short-term performance for long-term retention. If your exam is tomorrow, spacing and interleaving can't help much. But if you start using these techniques from the beginning of the semester, you'll retain far more with less total study time.

How does this relate to the Zeigarnik effect?

They're complementary ideas. The Zeigarnik effect says your brain holds onto unfinished tasks better than completed ones. Desirable difficulties says your brain learns more from effortful retrieval than from easy review. Both point to the same conclusion: a little struggle and incompleteness is better for memory than smooth, complete, comfortable study sessions.

The Uncomfortable Truth About Learning

Nobody wants to hear that the best study techniques feel bad. But that's what decades of research from Bjork's lab at UCLA keeps showing. The methods that feel effective (re-reading, highlighting, cramming) create an illusion of learning. The methods that feel frustrating (spacing, testing, interleaving) create actual learning.

The good news? Once you know this, you can stop judging your study sessions by how comfortable they feel and start judging them by whether they're creating the right kind of struggle.

Ready to add some desirable difficulty to your studying? Upload your notes to StudyLab and take a practice quiz before you feel ready. The questions you get wrong are the ones your brain will remember longest.