Why Harder is Better: The Surprising Science of Desirable Difficulties

The training session crushed it. Ninety-four percent completion. Satisfaction scores at 4.8 out of 5. Your VP sent a congratulatory email.

Three months later? Those same learners failed the audit. Couldn’t recall key steps. Couldn’t apply the principles they’d supposedly mastered.

What happened?

You fell into what cognitive scientist Robert Bjork calls the fluency trap. When learning feels smooth and effortless, it tricks everyone—trainers and learners alike—into believing real learning has occurred. The sensation of easy comprehension becomes a false signal. We mistake fluency for mastery.

We don’t just misread our learners. We misread ourselves.

The Problem With Smooth

For decades, L&D has optimized for one thing: comfort. Friction-free slides. Tidy sequences. Clear examples. Remove all obstacles. Make everything easy.

But here’s what the research keeps proving: Learning that feels easy tends to evaporate fast.

Bjork and his colleague Elizabeth Bjork spent decades studying this paradox. They discovered what they call “desirable difficulties”—specific challenges that make learning feel harder during training but dramatically improve retention and transfer afterward.

The term is precise. Not random obstacles. Not confusion or poor design—that’s undesirable difficulty. These are deliberate conditions that require learners to work just hard enough to deepen memory traces.

Think about the brain-muscle comparison you’ve probably heard. It’s useful shorthand, but the mechanisms work differently than simple resistance training. Neural strength doesn’t come from “resistance” the way muscles do. It comes from retrieval, reconsolidation, and re-encoding. Every time you force your brain to reconstruct knowledge from memory rather than simply recognize it, you strengthen the neural pathways. That effortful reconstruction is what builds durable learning.

Why Effort Builds Memory

When information flows too easily, your brain marks it as obvious. Disposable. “This is simple,” your working memory signals. “I won’t need to hang onto this long.”

But when retrieval or problem-solving takes real effort? Your brain flags that knowledge as important. That struggle triggers deeper encoding through what researchers call levels of processing. The harder your brain works to access information, the stronger the memory trace becomes.

Research from the testing effect studies proves this consistently. Learners who engage in effortful retrieval—even when they struggle initially—outperform their peers on every durable metric. Retention. Transfer. Novel problem-solving. The works.

The catch? They feel less confident during training. That’s the trap talking.

What Desirable Difficulty Looks Like

Let’s get concrete with two workplace scenarios.

Sales Training Showdown

Smooth Approach: Each day covers a single topic. Product features Monday. Objection handling Tuesday. Closing techniques Wednesday. Learners master one thing at a time, advance with confidence, leave feeling competent.

Feedback forms glow.

Strategic Difficulty: Mix everything from day one. Simulate real sales calls where features, objections, and closing blend unpredictably. Learners attempt tasks before you’ve finished teaching them. They fail. They wait a few days. They try again.

This feels messier. Harder. Less organized.

But field studies on interleaved practice show sales teams trained this way outperform traditional training by 20-25% on transfer tasks. They handle situations they’ve never encountered. The smooth-training group struggles when anything deviates from the script.

Software Training Reality Check

Smooth Approach: Polished screencasts. Expert demonstrations. Perfect walkthroughs. Learners follow along step by step. Easy to watch.

Easy to forget.

Strategic Difficulty: Start with a problem. “Here’s a business challenge. Solve it using the software.” No walkthrough. No guide. Just coaching.

Learners experiment. Make mistakes. Ask questions. Figure it out. You reveal job aids after they’ve wrestled with the problem.

This triggers what’s called the generation effect. When learners generate knowledge before receiving feedback—rather than just consuming pre-packaged information—retention shoots up. They’re not passengers. They’re drivers.

Eight weeks later, they’re solving novel problems independently while the screencast group keeps calling for support.

Four Techniques That Build Productive Struggle

Ready to redesign for retention? Start here.

1. Force Retrieval, Not Review

Recognition isn’t recall. When learners review notes, they recognize information: “Oh yeah, I’ve seen this before.” That recognition feels like learning. It isn’t.

Real learning happens when you close the notes and pull information from memory. When your brain has to reconstruct knowledge rather than simply recognize it. Testing knowledge before teaching it strengthens memory through what’s known as the pre-testing effect.

Try this: Begin modules with questions learners can’t yet answer. Let them struggle. Then reveal the answers. Studies show this alone can raise retention by roughly 30%.

The discomfort is the mechanism.

2. Mix Your Practice (Interleaving)

Grouping practice by topic feels tidy. Monday we practice scheduling. Tuesday we practice budgeting. Wednesday we practice risk assessment.

But this blocked practice hinders a critical skill: discrimination. When learners know in advance which tool they’ll need, they never learn to diagnose which situation calls for which solution.

Mixing related tasks forces learners to constantly decide which rule or skill fits each problem. That discrimination—figuring out what type of problem you’re facing—strengthens learning dramatically.

Try this: Combine scheduling, budgeting, and risk scenarios in unpredictable order. Every session should require all three skills mixed together. Just like real work.

3. Space Learning Over Time

Marathon workshops feel efficient. Get everyone in a room. Cover everything. Done.

Except it doesn’t work.

The spacing effect—one of the most robust findings in cognitive science—shows that distributed practice outperforms massed sessions every time. The mechanism isn’t about preventing forgetting. It’s about leveraging partial forgetting. When learners return after a delay, they’ve lost some information. Retrieving it takes effort. That effortful retrieval after partial forgetting builds more durable memory than continuous exposure ever could.

Try this: Replace your next eight-hour workshop with four two-hour sessions across four weeks. Watch retention scores climb.

4. Vary Your Examples Wildly

Using the same polished example repeatedly feels clear and consistent. But it builds narrow understanding.

When you show a concept working in radically different contexts, learners have to extract the underlying principle that works across situations. That extraction builds flexible schemas—mental models that transfer.

Teaching “clear communication”? Don’t show three email examples. Show clear communication in an email, a difficult conversation, a presentation, and a technical document. Force learners to figure out what makes communication clear regardless of medium.

Try this: For every principle, prepare three examples from completely different domains. Ask learners to explain how the same concept applies to each. That explanation strengthens their mental model.

The Satisfaction Score Trap

Here’s where you need courage.

Training that incorporates desirable difficulties often earns lower immediate satisfaction ratings. Learners don’t enjoy struggle. It feels harder. Less comfortable. It doesn’t produce that immediate “I’ve got this!” sensation.

And here’s the uncomfortable truth: Satisfaction scores don’t predict performance. In fact, research on metacognitive accuracy shows that confidence and actual competence often correlate negatively. The most confident learners sometimes learned the least.

So what should you measure?

• Retention at 30, 60, 90 days
• Transfer to novel contexts
• Performance under pressure
• On-the-job application

These metrics reveal whether training works. Satisfaction scores reveal whether it felt good. Sometimes you get both. Often you don’t.

Choose effectiveness.

Making the Shift

If you’ve spent years optimizing for ease, this requires a philosophical change. Here’s your roadmap.

Audit for over-smoothness. Look at your last course. Where did you make things too easy? Where could learners retrieve instead of review? Where did you organize practice too neatly?

Educate stakeholders early. Share this research before launch. Help leaders understand why short-term discomfort produces long-term results. Get buy-in for training that feels different.

Start small. Don’t overhaul everything at once. Add one desirable difficulty—retrieval practice, spacing, or variation—to your next project. Build confidence through experience.

Distinguish difficulty from confusion. This is critical. Not all difficulty is desirable. Confusing instructions aren’t productive struggle. Unclear objectives aren’t strategic challenge. Poor design isn’t cognitive load—or rather, it’s the wrong kind. Cognitive load that aids learning helps learners process and integrate information. Overload or unclear design just overwhelms. Know the difference.

The Choice You’re Already Making

Every time you design a learning experience, you’re making a choice—whether you realize it or not.

Do you want learners to feel confident today, or be competent three months from now?

You can optimize for comfort during training and watch everything evaporate within weeks. Or you can introduce strategic struggle during training and build capability that lasts for months.

Most organizations chase high satisfaction scores and smooth delivery without realizing they’re sacrificing actual learning. They wonder why training doesn’t transfer. Why performance doesn’t improve. Why they keep retraining the same content.

You now know why.

Desirable difficulties aren’t about making training arbitrarily hard. They’re about targeted challenge that strengthens memory. Strategic friction that builds capability. Productive struggle that produces lasting results.

Your learners might not thank you immediately. But three months later, when they’re the only ones who remember what they learned? When they’re solving problems their peers can’t touch? When they’re applying principles in situations you never trained them for?

That’s when the choice you made will prove itself.

This is the first in a series on foundational learning research. Each principle will challenge conventional L&D wisdom. Each will give you evidence-based tools to design training that actually works.

The question isn’t whether you’ll face this choice.

You’re facing it right now with your next course.

Choose wisely.

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Key Research

Core Concept:

• Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings. In J. Metcalfe & A. Shimamura (Eds.), Metacognition: Knowing about knowing. MIT Press.
• Bjork, E. L., & Bjork, R. A. (2011). Making things hard on yourself, but in a good way: Creating desirable difficulties to enhance learning. In Psychology and the real world: Essays illustrating fundamental contributions to society. Worth Publishers.
• Bjork, R. A., & Bjork, E. L. (2020). Desirable difficulties in theory and practice. Journal of Applied Research in Memory and Cognition, 9(4), 475-479.

Supporting Evidence:

• Roediger, H. L., & Karpicke, J. D. (2006). The testing effect. Psychological Science, 17(3).
• Rohrer, D., & Taylor, K. (2007). The shuffling of mathematics problems improves learning. Instructional Science, 35(6).
• Cepeda, N. J., et al. (2006). Distributed practice in verbal recall tasks. Psychological Bulletin, 132(3).