We have playlists for our favorite music, but don't re-consume great information nearly enough. Almost certainly you've once watched a documentary (or read a book) about the environment, after which you ponder how to reduce your footprint: an electric car, eating less meat, or voluntarily paid carbon tax on your air-travel emissions. Then, after a few weeks, the effects mostly fade, and you gradually return to baseline...
This cycle of a bee entering your bonnet for a short period, only for another bee to take its place, is ineffective. We pick up gems from conversations, articles, books, and videos, only to use them for a few days or weeks. Most things we learn, we forget, unless our environment strongly nudges us to consider those ideas repeatedly. However, most ideas don't leap from medium-term memory into long-term principles. How can we increase our odds of compounding ideas on top of each other, instead of leap-frogging between new ones?
Spaced repetition is the simple idea that the probability of remembering an idea for the long-term increases dramatically if we're reminded at an intentional, exponential schedule. We might discover that the word for the effect where we learn a new word and start noticing it everywhere is called the 'frequency illusion.' To not forget this, we make sure we're exposed to this piece of information a few days from now, then a week after that, two weeks after that, then a month, three months, and then every six months from there. Spaced repetition is a well-studied effect, and many (including myself) have had success with this through flash-cards. We expose ourselves to the piece of information just before we would forget it, refreshing the memory.
However, the effect doesn't need to be constrained to fun facts on flashcards. It can be deep, complex ideas as well. Ideas or ways of thinking that we incorporate deeper, and deeper into our wetware with each successive re-consumption of an article, book, or video on some schedule. In the past year, I've been interested in exposing myself to an increasing amount of spaced repetition outside of flashcards.
Readwise helps me by re-surfacing highlights from my Kindle and Instapaper. Quite a few times reading through the daily digest from Readwise, a highlight came at just the right time to implement it that day or sparked new connections to form more connected memories. My pet theory is that the truly useful ideas that make it from books to our life principles are the ones that strike us at just the right time where we needed that idea. Through spaced repetition, we increase that probability dramatically.
In general, the more well-connected an idea in your head, the higher the likelihood that it surfaces at the right time. To me, the definition of a useful idea is one that's readily available when you need it. It is hard work, and takes time, to mold the neural connections to elevate an idea to this status. A 100, time-tested ideas stored in this fashion are worth a thousand times more than 10,000 that enter and leave rapidly.
For example, a few months ago, a highlight about survivorship bias came up. This cognitive bias points out that we don't adequately value the information not present. We may be inclined to say that 'old buildings are more beautiful' when in fact, when you think about it, only the beautiful old buildings survive. The ugly ones are torn down, and new ones will take their place. This idea came up in my Readwise digest as I was walking to work, at just the right time. It was highly applicable to a problem we were working through on the team. As a result, I now see survivorship bias everywhere I look. It feels like that one, deep application made an order of magnitude more neurons connect than anything I'd done previously.
While flash cards and Readwise have been helpful, it doesn't solve the problem for me of content that requires more deliberation. A video, article, or entire book. For the first two, a few months ago I built a script that will re-surface article or videos saved in Instapaper on a spaced repetition schedule. For example, I liked this article about Expectations vs Forecasts in my Instapaper and archived it. A week later, it came up on top of my to-read list again. Then a month after that. I'll see it again in another few months, for it to finally only be read every 6 months. This creates a 'playlist' of great articles, with new articles coming up once in a while too. Spending more time on a few great articles is providing me more value than trying to read everything. I now mostly skim articles on the first read. If it's interesting, I'll 'like' it and go in more depth the second time. I'm finding myself taking more notes and highlights each time it pops up again. I add videos to Instapaper too, to recycle the same system.
While this is good, I hope that the next-generation of read-it-later services will build spaced repetition straight into their core product. I hope they'll help with heuristics on when to read old, and when to learn new. Perhaps treat the inbox, not as a queue, where what I just added comes up on top, but what I added months or years ago is next. This helps avoid the cycle of spending the majority of your time consuming media that expires rapidly.