Avoid orphan spaced repetition memory prompts

When adding prompts to a Spaced repetition memory system, it’s usually a mistake to write prompts about a detail that seems interesting, but which is disconnected from everything else you’re thinking about. Spaced repetition memory prompts should connect and relate ideas—and it’s even better to make them connect and relate to ideas that you’re regularly thinking about.

“Orphan questions” (coinage per Michael Nielsen, 2018) cause two important problems:

  1. After a while, these isolated prompts often start to feel like a burden in the review session, disconnected from what you actually care about (contra The critical thing to optimize in spaced repetition memory systems is emotional connection to the review session and its contents)
  2. You’ll likely have more trouble remembering the answers to these questions, since they won’t be naturally reinforced through your daily life. Even if you do remember the answers, there’s a danger that they’ll be pattern-matched because they don’t connect to other knowledge (Spaced repetition memory prompts should be written to discourage shallow “pattern matching”)

At least for me, one common situation that often results in orphan questions is: someone shares an interesting paper in a field I know nothing about; I read it and write a few prompts. A few months later, I have no idea why I’m reviewing them. They don’t relate to anything I’m doing or thinking about.

Michael underscores the particularly harmful case of “lonely orphans”:

It’s particularly worth avoiding lonely orphans: single questions that are largely disconnected from everything else. Suppose, for instance, I’m reading an article on a new subject, and I learn an idea that seems particularly useful. I make it a rule to never put in one question. Rather, I try to put at least two questions in, preferably three or more. That’s usually enough that it’s at least the nucleus of a bit of useful knowledge. If it’s a lonely orphan, inevitably I get the question wrong all the time, and it’s a waste to have entered it at all.


Nielsen, M. (2018). Augmenting Long-term Memory. http://augmentingcognition.com/ltm.html

Last updated 2023-07-13.