Epstein introduces the term “desirable difficulties” in Chapter 4, borrowing it from cognitive psychologist Nate Kornell. He defines it as “obstacles that make learning more challenging, slower, and more frustrating in the short term, but better in the long term” (85). Epstein uses the term in the context of a discussion about methods teachers use to ensure learning is retained, but beyond the context of Chapter 4, the term aligns with his overall argument that success and creativity are not necessarily attained through direct, rote paths. 

Psychologist Angela Duckworth coined the concept of “grit” when studying outcomes of the U.S. Military Academy’s orientation. She sought to understand what factor led some to succeed in the highly rigorous environment while others abandoned it. Epstein defines grit as “work ethic and resilience, and […] ‘consistency of interests’” (133). However, he argues that grit can actually prevent someone from succeeding when it causes them to stick to an idea or plan they might be better off modifying or abandoning. 

Hyperspecialization is a shorthand term for sustained, focused practice commonly used in fields like sports, chess, and music to develop highly-trained experts. Epstein acknowledges that this method is suitable in many cases for some fields: “[a]t its core, all hyperspecialization is a well-meaning drive for efficiency” (286).