Robert Bjork

In Range, Bjork is the psychologist who first used the phrase “desirable difficulties” in 1994 — the load-bearing Learning-science concept the book leans on. The key warning attributed to him is that teachers and students “must avoid interpreting current performance as learning”: good test performance during learning can indicate “fast but fleeting progress” rather than durable mastery. Range builds on his work to argue that desirable difficulties like testing and spacing make knowledge stick, while making connections and interleaving make it flexible — all of which slow learning and hurt short-term performance, but deepen retention and transfer.

Context: Robert A. Bjork is a cognitive psychologist at UCLA known for his research on human memory, retrieval practice, and the “desirable difficulties” framework in the science of learning.

Where this appears

• Range — credited with coining “desirable difficulties” (1994) and the warning not to mistake current performance for learning.