This article dissects Justin Sung’s PACER learning system—five knowledge types grounded in neuroscience, each with its own optimal learning strategy. If you’ve ever felt you’re “learning too slowly” or “forgetting too fast,” this is for you.

PACER Learning Method Explained

The internet is revisiting this video because we all feel we’re “not smart enough.”

Recently, a post on X recommending Justin Sung’s “How to Remember Everything You Read” garnered 11 million views in just 3 days. The video has now accumulated over 8.6 million views on YouTube.

Since the information age began, it seems we’ve all developed severe “knowledge anxiety”—always feeling we’re learning too slowly and forgetting too fast.

In this video, author Justin Sung proposes a system called PACER from the perspective of neuroscience and cognitive psychology, designed for efficiently understanding and digesting knowledge.

The Core Cognitive Shift: From “Hoarding” to “Digesting”

Most people fall into knowledge anxiety when pursuing self-improvement, believing that reading faster and more is better.

Old mindset: Learning = input, trying to memorize all details, scanning books into the brain like a scanner.
New mindset: Learning = input + digestion.

However, without “digestion,” even if you read extensively, 90% will be forgotten (the author calls this “mental regurgitation”). True cognitive upgrade doesn’t depend on how much you’ve “seen,” but on how much you’ve retained and can transform into problem-solving ability.

The PACER System

The PACER model is essentially training in metacognition— “thinking about thinking.”

It requires you to, at the first moment of encountering information, determine “what type of information is this?” and then invoke different brain resources to process it. It divides knowledge into five types:

P - Procedural Knowledge

Characteristics: Procedures that teach you how to do something (e.g., programming, first aid steps).
Strategy: Practice immediately. Don’t memorize steps by rote; learn by doing. Action trumps memory. For skill-based knowledge, bodily memory is more reliable than brain memory.

A - Analogous Knowledge

Characteristics: Information that allows you to associate with known things.
Strategy: Critique. Consider where the new and old knowledge are similar, where they differ, and in what situations the analogy breaks down. By hanging new knowledge on the trunk of old knowledge, your cognitive network expands exponentially, rather than piling fragments in isolation.

C - Conceptual Knowledge

Characteristics: Information explaining principles, theories, and relationships (e.g., scientific principles, economic models).
Strategy: Map. Draw mind maps to build nonlinear knowledge networks. The difference between experts and novices is that experts’ brains are networked, novices are linear. Through the mapping process, you’re training yourself to see systems and connections behind things like an expert—not isolated single points.

E - Evidence Knowledge & R - Reference Knowledge

Characteristics: Specific cases, data, or minute details (e.g., historical dates, specific values).
Strategy: Store & Rehearse. Don’t spend massive effort memorizing during reading; first note it down in notes or flashcards, then use spaced repetition (e.g., Anki) later. Learn to allocate brain resources. Don’t spend precious deep-thinking time on boring data; outsource them to tools or leave them for fragmented time.

The Mindset for Cognitive Growth

As ordinary people, our goal is to build a logic network, not a database.

Accept that “forgetting” is normal; combat it through “active connections.” The video mentions that while photographic memory like Kim Peak (the real-life inspiration for the movie “Rain Man”) is remarkable, it doesn’t provide advantages in high-level logical reasoning and problem-solving. As ordinary people, our goal is to build a logic network, not a database.

Slow is fast. To balance “input” and “digestion,” you may need to slow down your reading speed, or even stop halfway to draw diagrams or think. This seemingly “inefficient” pause is precisely the critical moment for neurons to form connections. True diligence is deep mental engagement, not the speed of eye movement.

Shift from “student mindset” to “expert mindset.” Student mindset tends to be passive reception, linear reading, and rote memorization, while expert mindset is active filtering, networked construction, and validation through practice. The PACER system is a tool that forces you into expert mindset mode.