Understanding how we learn: An interview with John Sweller

John Sweller is one of the most influential figures in educational psychology. Best known for advancing and developing the Cognitive Load Theory, his work has reshaped how we understand learning. In a recent trip to Sydney, Australia, the President of Iniciativa Educação had the opportunity to explore some of the highlights in Sweller’s career that became pivotal for today’s educational practices.

A life dedicated to memory and learning

John Sweller’s path to psychology was not as conventional as one might expect. As a university student, he started by enrolling in dentistry but soon realized it was not exactly what he was meant to do. While his interests shifted, he kept being pushed away from this early career choice. «The dentistry faculty certainly didn’t like me,» he jokes.

He soon focused on learning theory. Sweller spent most of his career at the University of New South Wales, conducting rigorous experimental research using randomized controlled trials to test educational methods. His research led him to explore how people acquire knowledge, ultimately culminating in his magnum opus: the Cognitive Load Theory.

The disconnection between cognitive science and educational practices is a major theme in Sweller’s work. This division also happens in a somewhat minor but telling linguistic example: the artificial separation between memory and learning. Advocating for his own evidence gathering over the years, he criticizes how memory is too often undervalued in education. Learning is praised, whereas memorization is regarded as something negative which should be avoided altogether — when in fact, Sweller argues, «they’re identical. You can’t distinguish between memorizing and learning.»

Primary and secondary knowledge

Memory is not just a passive storage system but the foundation of intelligence and reasoning. «Without our long-term memories, we cannot act intelligently,» Sweller states, bringing forward the critical role of knowledge accumulation (also highly undervalued in education, in his opinion) in cognitive development and learning.

Based on David Geary’s work, Sweller makes a fundamental distinction between two types of knowledge:

• Biologically primary knowledge, which includes innate abilities like problem-solving, communication, and social interaction. These skills develop naturally and do not require formal teaching.
• Biologically secondary knowledge, which includes learned skills like reading, writing, and mathematics. These must be explicitly taught because they are not naturally acquired.

This distinction explains why humans can learn to speak effortlessly but struggle with literacy and numeracy. «Until about one and a half centuries ago, virtually everybody in every society was unable to read and write. You didn’t pick it up just by looking at books,» he emphasizes.

Schools exist precisely to teach biologically secondary knowledge, and effective instruction should reflect that reality. Sweller warns against assuming that students will «discover» knowledge naturally, as some educational models suggest. «Students are the only class of people on Earth to whom we would apply that particular rule,» he remarks.

Yet, despite his claims, Sweller recognizes that there are still unanswered questions — particularly regarding the transition from guided instruction to independent problem-solving. Determining the optimal moment for this shift remains a major research challenge. When do we switch from one procedure to the next? How do we know the best of way of doing that? That’s what empirical evidence is for.

The cognitive revolution and the role of memory in learning

George Miller’s famous paper on working memory («The magical number seven, plus or minus two», published in 1956) shaped modern psychology and established itself as one of the major works of what was later coined as the «cognitive revolution.» The article described some limits to our human capacity to process information — something that has been widely disregarded by educators. «While that work was directly relevant to education, it was ignored by education,» Sweller laments.

Foundational concepts such as working memory limitations are still dismissed by most educators today. Many educational theories assume students have unlimited cognitive capacity, neglecting constraints that might impact their learning. This oversight, Sweller explains, has led to ineffective instructional approaches that overload students instead of supporting them in their learning.

Many educational theories assume students have unlimited cognitive capacity, neglecting constraints that might impact their learning

Sweller’s life work has precisely focused on the importance of reducing unnecessary cognitive load in teaching, ensuring that students can effectively process and retain new information — what we commonly refer to as the Cognitive Load Theory.

Cognitive Load Theory in practice

The Cognitive Load Theory is based on the understanding that working memory is limited in capacity and duration, making structured instruction crucial. Sweller’s research has identified several instructional principles that optimize learning:

• The Worked Example Effect: Novices learn best through worked examples before attempting problems on their own. «You don’t give [students] one or two worked examples. You give them lots and lots of worked examples demonstrating how you use what you’ve been taught.»
• The Redundancy Effect: Providing unnecessary information can overload working memory instead of aiding comprehension. «If you give a worked example to someone who already understands the topic, it has negative effects. They don’t need it.»
• The Expertise Reversal Effect: As learners advance, direct instruction becomes less effective, and independent problem-solving becomes more beneficial. «For novice learners, studying worked examples is better than solving the equivalent problems. With increasing expertise, that difference contracts, then disappears before, lastly, reversing.»
• The Transient Information Effect: Spoken and animated information is harder to retain than written material. «Learning through videos is the same as learning through oral information. It’s transient. You may be better off presenting a series of still images rather than a video.»

One of the key strengths of the Cognitive Load Theory is that it is not just a theoretical framework — it is tested through controlled trials. Sweller emphasizes the importance of experimental validation in education.

By systematically comparing different teaching approaches, researchers have been able to confirm the effectiveness of strategies such as worked examples and structured instruction. Sweller acknowledges that conducting these trials in education is challenging, but he finds them necessary in order to improve instructional design.

The Challenge of Transitioning from Novice to Expert

One of the biggest unresolved questions in educational psychology is determining when students should transition from guided instruction to independent problem-solving. Sweller insists that beginners require structured guidance: «For a novice, you need guidance. Putting a novice into a situation where they have to work things out for themselves… there is absolutely nothing in the literature that suggests that’s a good idea.»

However, at a certain stage, problem-solving practice becomes necessary. The challenge is identifying when to make that transition. While experienced teachers often develop an intuitive sense of when students are ready, Sweller believes a more systematic approach is needed. «Right now, we do not have a clear test indicating when a student knows enough to work independently. It’s up to teacher judgment.» Research in this area, he argues, is essential for improving instructional methods.

This article is based on the interview Nuno Crato did with John Sweller in Sydney, in July 2024. For the full interview, please click here.