Habits are costly

The title of this post could mean at least two things, depending on whether your perspective is from before or after the habit is formed.

From the after perspective, the title infers a bad habit and an undesirable consequence. But what about good habits? Are they costly too?

I am a Habitican. This means I have an account in the online RPG called Habitica, which is an adorable community full of people of all ages from all over the world who have gamified their lives by turning daily tasks and to-do lists into quests, complete with camaraderie and rewards. This is my avatar, @CrankyWombat, flying high on cloud nine in the winter night sky on my Hopeful Hippogriff and accompanied by my newly-hatched Cheetah, whom I will feed until I can ride him too.

Silly and amusing fluff aside, this game really is useful for forming good habits if you use it right and particularly if you find yourself in good company on your quests. A very wise fellow member of my Party posted this one day in the chat room:

So… I’m noticing a cool and unsettling pattern with habit formation. Consistently, there are a nasty few days when I’ve been keeping up with a new habit for a while (haven’t tracked the time period – should) and all of a sudden the effort required goes WAY up. Narrative content varies (too busy, too sick, shouldn’t have to, don’t need to, stupid anyway, who do you think you are?, don’t they know who I am?, etc.) but the sensation is the same. I keep going though the unpleasantness for a few days, and then – poof! – the unpleasantness vanishes. Now the habit is completely entrenched and effortless (other than the inherent effort of the task). It seems to have nothing to do with how difficult or even trivial the habit is, so I’m guessing it’s my brain saying “Hey! Rewiring is expensive! Are you sure this is absolutely necessary?”

Now, I am no neuroscientist, but I’m pretty sure my friend is onto something, and a quick Google search for “brain scan in habit formation” pulled up two results on Science Daily.

The first describes a research study by O’Hare et al. (2017) out of Duke University where a group of neuroscientists found evidence, in experiments with mice, of “fast-spiking interneurons” (FSIs) buried deep in the striatum of the brain that can be considered “master controllers” of habit formation. These relatively rare cells are intricately connected to both “go” and “stop” pathways made up of far more abundant types of neurons. These pathways incite and inhibit action, respectively, and both become stronger when a habit is formed. The FSIs were found to control the whole kit and kaboodle, meaning an entire habitual behaviour could be disrupted by inhibiting this single cell.

A more recent study by Martiros et al. (2018) out of MIT, also featured in Science Daily, explores the idea of “chunking” in habitual behaviour. As it turns out, when we are forming a new habit, the whole sequence of behaviour is governed by hard-working neurons that fire as you perform each step in a series of tasks – for example, washing your hands before you eat, locking the door when you leave the house, or reaching for a glass of water instead of the bottle of cola in the fridge. As the habit is formed, the firing activity becomes focussed at the beginning and end of the series of tasks, leaving the intermediate steps to be carried out on autopilot.

I think both of these studies fit the intuitive conclusion of my fellow Habitican rather nicely. Rewiring IS expensive, because there is a lot of energy invested in both breaking an old habit and forming a new one, and whether the habit is action (doing the right thing) or inaction (not doing the wrong thing), the neural rewiring required is essentially the same, and it is indeed costly. In fact, you might say that you can’t break a habit without forming a new one, and conversely, you can’t form a new habit without breaking an old one.

Even if you don’t geek out at the science like I do, the take-home message is this: there’s a reason it’s hard, and there’s a reason we rebel against our best efforts to take care of ourselves and do the right thing. The reason is both biological and evolutionary: rewiring is expensive, and we have evolved to be frugal with our use of energy.

I don’t know about you, but I find that this kind of information helps me through the tough bits. Knowing it’s supposed to be hard makes me less inclined to give up, and it helps me to be compassionate with myself during the rebellious “I don’t wanna” phases of personal development. Rewiring is expensive. Thanks, @Pseudoscorpion, for pointing that out. Onwards, Habiticans!


Nuné Martiros, Alexandra A. Burgess, Ann M. Graybiel. Inversely active striatal projection neurons and interneurons selectively delimit useful behavioral sequences. Current Biology, 2018; DOI: 10.1016/j.cub.2018.01.031

Justin K O’Hare, Haofang Li, Namsoo Kim, Erin Gaidis, Kristen Ade, Jeff Beck, Henry Yin, Nicole Calakos. Striatal fast-spiking interneurons selectively modulate circuit output and are required for habitual behavior. eLife, 2017; 6 DOI: 10.7554/eLife.26231