Why Your Brain Deletes What You Just Studied for the CISSP Exam

If you’ve ever read the same page in your CISSP study guide nine times—only to forget it completely the next day—you’re not alone.

This isn’t just a study problem. It’s biology. Psychology. Even survival instinct.

But it’s also fixable.

Over the years of helping thousands of CISSP students—from first-timers to security veterans—I’ve seen this exact frustration unfold again and again. And every time, it starts with one quiet thought:

“Why can’t I remember this? What’s wrong with me?”

The answer? Absolutely nothing. Your brain is working exactly as designed. The real issue is that most of us try to study in ways that actually tell the brain not to remember.

Let’s dig into why your brain deletes what you just studied—and more importantly, what to do about it.

The Illusion of Learning

Here’s the trap: you read a dense section on access control models—RBAC, ABAC, DAC—and each time, it feels easier.

But that “easy” feeling is the illusion of fluency.

A 2006 study by Roediger and Karpicke showed that students who re-read material performed worse than students who tested themselves on it. The re-readers felt confident… but couldn’t actually recall the information when it mattered. Sound familiar?

That’s because reading gives you familiarity, not memory. It’s like watching someone drive stick and thinking you’ve got it—until it’s your turn behind the wheel.

In the CISSP world, I’ve seen students “feel solid” about threat modeling or crypto—only to blank out on a practice question. That disconnect is where most frustration begins.

And that’s where we start to retrain the brain.

How Memory Actually Works

Memory begins in working memory—your mental RAM. It’s limited. Most people can only juggle 4–7 pieces of information at a time.

To move data into long-term memory, your brain needs a signal: this is worth saving.

Passive reading doesn’t trigger that signal. It’s like typing a brilliant paragraph… and forgetting to hit Ctrl+S. Gone.

Cognitive Load Theory backs this up: when your brain is overloaded (which happens a lot during CISSP study), it just drops excess info to survive. And cybersecurity concepts—especially when studied in isolation—often get treated like disposable clutter.

The fix? Learning methods that trigger encoding on purpose. Because once you study with intention, the brain listens.

Forgetting Is a Feature

According to UCLA’s Robert Bjork, your brain is built to forget. That’s not a flaw—it’s an optimization. If we remembered everything, we’d be drowning in data.

The brain keeps what’s emotionally relevant, spaced out over time, and—most importantly—earned through effort.

That’s why rereading isn’t enough. It feels familiar, so your brain ignores it. But the struggle to recall something? That’s a memory event. That’s how the brain flags information as important.

And honestly… this is one of the most overlooked parts of CISSP prep. Too many smart people spend weeks highlighting and re-highlighting, hoping something will stick.

But memorization doesn’t happen from comfort. It happens from friction.

So What Should You Do Instead?

1. Active Recall

Close the book. Ask yourself: What’s the difference between RBAC and ABAC?If you struggle—that’s good. Struggle is memory formation in progress.

Active recall is like weight training. You’re not just storing info—you’re creating retrieval paths to access it later under pressure. (Like… say, on exam day.)

This is why, in my own sessions and materials, I never stop at “read this.” I force recall. Because that’s where the shift happens.

2. Spaced Repetition

Don’t cram. Space it out.Hermann Ebbinghaus discovered the Forgetting Curve—and how it can be reversed with strategic review.

Revisiting topics just before you forget them re-strengthens memory. A few short reviews over time beat a marathon study session every time.

In fact, every flashcard or drill I build into my materials is placed with this in mind. There’s a science to when things are reviewed—not just what’s reviewed.

3. Interleaving

Mix up topics. Bounce between BCP and cryptography. Rotate in risk management.

This mirrors how questions are asked on the CISSP exam: unpredictable and cross-domain.

Interleaving creates stronger mental links, which is exactly how a security professional is expected to think—fluidly, not in silos.

Honestly, this is one of the subtle things I’ve woven into every high-level question I write. It’s not just about getting the answer—it’s about teaching your brain to navigate uncertainty.

4. Teach It

Teach what you just learned—to your dog, your fridge, or your reflection.

The Feynman Technique is simple: if you can explain it clearly, you understand it. If you can’t, you’ve just found your weak spot—and now you know where to focus.

When I started out, I talked out loud constantly. Still do. It’s part of how I refine every video, every analogy, every explanation I build for students.

You don’t need a classroom. You just need a curious mind and a willing listener—even if it’s your own voice.

Final Thoughts: You’re Not Broken

I’ve been teaching CISSP for a long time now. And I’ve seen this stage—where nothing seems to stick—happen to some of the sharpest minds in the industry.

You’re not broken. Your brain isn’t failing you.

It just hasn’t been shown how to learn this properly… yet.

Once you stop fighting against your memory and start working with it, things change. You don’t need perfect recall. You need moments of effort—little memory signals that say, “This is important.”

And over time, that effort stacks up. That’s how real professionals are built—not by memorizing facts, but by wrestling with concepts until they bend.

If you try even one of these techniques today—active recall, spaced repetition, mixing topics, or just teaching something aloud—you’re already ahead of where you were yesterday.

And if you’ve made it this far into this article? You’ve already got what it takes.

All the best on your CISSP exam.

Sources & References:

• Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention.

• Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings.

• Sweller, J. (1988). Cognitive load during problem solving: Effects on learning.

• Ebbinghaus, H. (1885). Memory: A Contribution to Experimental Psychology.

• Brown, Roediger, & McDaniel (2014). Make It Stick: The Science of Successful Learning.