Tell desirable difficulty from plain obstacle

Keep difficulties you can overcome with effort; remove ones that just block you.

Why it works

A desirable difficulty makes retrieval and processing more effortful in a way you can still succeed at, and that successful effort is what strengthens memory. An undesirable difficulty — illegible text, missing prerequisites, pure confusion — raises effort without any productive payoff, consuming working memory on the obstacle instead of the learning. The deciding question is whether the difficulty is one you can work through.

How to do it

1. When study feels hard, ask: is this effort I can succeed at, or a wall I cannot pass?
2. Keep difficulties tied to retrieving and discriminating the actual content.
3. Remove difficulties that come from poor materials, missing basics, or pure confusion.

Evidence

Bjork’s framework, supported by decades of memory research, distinguishes difficulties that enhance long-term learning from those that merely impair performance; the same manipulation can be desirable or not depending on the learner’s ability to overcome it. Bjork (1994) first named the principle in the metamemory literature, and Bjork & Bjork (2020) revisit it with a synthesis of how it holds up in real instructional practice. (rct)

Whether a difficulty is desirable depends on prior knowledge — what helps a prepared learner can overwhelm a beginner — so it is conditional, not absolute.

Sources

• Bjork & Bjork, work on desirable difficulties and the distinction between learning and performance
• Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings. In J. Metcalfe & A. Shimamura (Eds.), Metacognition: Knowing about Knowing (pp. 185–205). Cambridge, MA: MIT Press.
• 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.

Common mistake

Assuming all struggle is good and grinding through difficulties that have no payoff, or assuming all struggle is bad and removing the productive ones too.