Noah Brier | April 8, 2022

Interstitial Journaling Edition

On caches, focus, and memory

Noah here. The more time you spend around computers, the more you start to try to apply their metaphors to your life. Whether or not it’s real, we see ourselves—and especially our brains—in their machinations. I wrote about this in last year’s Brain Edition:

Misunderstanding how the brain works and applying imperfect metaphors seems to be a basic part of humanity. “Our shoddy thinking about the brain has deep historical roots,” an excellent Aeon piece from a few years ago explained, “but the invention of computers in the 1940s got us especially confused. For more than half a century now, psychologists, linguists, neuroscientists and other experts on human behaviour have been asserting that the human brain works like a computer.” 

Why is this interesting?

Scientifically accurate or not, I’ve found some computing metaphors particularly helpful. One, in particular, is the idea of cache warming. Computers use caches in all sorts of contexts to quickly retrieve frequently used data. For example, a web app might make queries to a database, and some of these take a long time to process, so we store the results of frequently used queries in a cache so we don’t have to go back to the database each time the page loads.

Cache as a metaphor is a pretty easy one to apply broadly. We physically “cache” lots of stuff in our lives for easy access: keys near the door, coats on a coat rack, and so on. But the more interesting part of the metaphor is around the idea of warming a cache. Historically at least, when you reboot a database, things were slow until the cache had time to get up to speed with the most popular queries. Again, things are a bit different with super-fast solid-state hard drives, but the concept still stands: when you shut something down and restart it, the system needs some time to get back up to speed.

I always thought this was a good way to think about deep work. If I’m writing code or deep in a spreadsheet, I’m loath to leave or be interrupted because it can take a lot of time to get back up to speed. It feels a lot like a cache problem because a big part of the reason why it’s hard to jump back in is that you have to get yourself reacquainted with all the nuances of the work. If you were in a spreadsheet, you may need to retrace how different fields are updating other fields and which formulas you used to make that column work properly. When you’re in the middle of the work, it's all that’s part of your recent memory—so it’s not a big deal to access it quickly as needed.

There’s lots of research about the cost of interruptions, but I’m not so interested in that (nor am I sure I believe all of it). A few years ago I ran across the idea of interstitial journaling and it’s been something I’ve tried to practice since. The idea is super simple (or at least my interpretation of it is): every time you switch tasks you try to write down a line about what you were thinking/working on at that moment. It can be as quick as:

5:36pm. Just finishing up WITI on interstitial journaling. Need to come back and write a conclusion. Might bring it back to the makers/manager schedule or something similar.

Like a spark file, it’s meant to be small and kept in a text doc. The point of the tiny entry is to capture as much of the context as possible. The real cost of interruptions is trying to get yourself back to what you were thinking. Interstitial journaling is a kind of hack to deal with that problem—you don’t need to try to figure out the context if you lay it out for yourself in a quick note. I’ve found the more descriptive and emotive the note is, the more likely I am to quickly “warm the cache” and get back to work. (NRB)

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Thanks for reading,

Noah (NRB) & Colin (CJN) 

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