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up:
  - "[[Habits Map]]"
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created: 2014-01-01
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There are two metaphorical ways to talk about habits: additive and subtractive.

**Subtractive**
When you repeat the same action, it's like walking the same path: eventually a trail forms. [^1]

**Additive**
When you repeat the same action, it's like adding another strand to a string: eventually that string becomes a rope, and that rope becomes a cable.

I say additive is the truest metaphor for habit formation because that's what is happening in the brain. Actions cause specific neurons to connect. The more they connect, the more efficient they become at connecting. This is through dendrites growing spines (see [[The neural formation of habits is additive]]).

To conclude, even those neural formations are additive.

### Counterpoint
But they're not actually. Consider the trail. Even though the removal of undergrowth and twigs seems subtractive, it's actually additive from the POV of *throughput*. The amount of content and/or the speed of travel has increased. 


[^1]: As I return to this old idea, I'm struck with a contradiction. While the terrain wears away (subtractive), the speed of travel increases (additive). So if the point of reference changes from the terrain to the traveler, even the subtractive example contains an additive component. 2020-05-27
