Limits of Control

Do you ever get the feeling that you’re “running low” on self-control?

Nom nom nom. Willpower fail.

Like attention, self-control seems to be a limited resource in a connectome. In fact, these may not be two separate entities at all, but aspects of a single mental resource, which we might call volition, or perhaps willpower. Many experiments have shown that the more self-control a person exerts – especially over an extended period of time – the less attention they can devote to subsequent cognitive demands, like solving puzzles or taking initiative.

This might seem like an obvious fact, but what’s really fascinating is the variety of ways in which it can play out.

Here’s one example, from an article on a 1998 study by Baumeister et al.

[The researchers] had food-deprived subjects sit at a table with two types of food on it: cookies and chocolates; and radishes. Some of the subjects were instructed to eat radishes and resist the sweets, and afterwards all were put to work on unsolvable geometric puzzles. Resisting the sweets, independent of mood, made participants give up more than twice as quickly on the geometric puzzles. Resisting temptation, the researchers found, seemed to have “produced a ‘psychic1 cost.’”

In short, a person can only make so many difficult decisions in a limited period of time, before he or she becomes mentally sapped and falls back on instinctual reactions. These mental resources appear to be crucial for a heterogeneous range of behaviors, from resisting a snack to solving a puzzle to tolerating annoying noises. As Wan et al. put it in their 2011 paper, “exerting self-control leads to a temporary depletion of regulatory resources, which in turn influences subsequent self-control behaviors.”

Wan et al. bring up the concept of construal levels to help explain this. The basic idea is this: our connectomes conceptualize rewards and punishments at several levels of abstraction, such as (in roughly ascending order of abstraction) immediate pleasure or pain, delayed gratification, concepts like “healthy” or “beautiful,” and ideals like “fair” or “worthwhile.” The more abstract and/or delayed a reward (or punishment) is, the more mental resources we need in order to be effectively motivated by it.

Here’s a practical example: after a day of mentally exhausting work, we’re more likely to choose a tasty meal than a healthy one. In other words, the more attention we’ve devoted to one task (or type of task), the less reasoning power is available for the next one – until we give our brains some rest and replenishment. This is true even if the types of tasks are completely unrelated.

One common “cure” for low energy and wandering attention is caffeine, but this chemical works less like an energy paycheck and more like a credit card – the boost it gives you now will only lead to higher mental debt in the long run. To understand how this works, let’s take a closer look at the neuropharmacology of caffeine.

Caffeine’s molecular shape mimics that of adenosine, a chemical that forms the “spine” of several larger molecules crucial for transporting energy around cells, such as adenosine triphosphate (ATP). Now, cells throughout the body (including neurons in the brain) have receptors specifically shaped to accept adenosine – you can think of the receptor as a molecular lock in the cell membrane, and adenosine as that lock’s key.

Adenosine, passing energy around in a cell's metabolism.

What caffeine does is latch onto cells’ adenosine receptors, acting as a receptor antagonist – in other words, it tricks the cells into thinking they’re full up on adenosine, which means there’s plenty of energy left. This triggers a cascade of physiological changes: sleepiness is suppressed, “excitement” chemicals like dopamine and epinephrine (a.k.a. adrenaline) are released, and you get a boost of energy.

But your connectome will eventually get wise to the lack of adenosine, and will close down the party. This is why a cup of coffee can keep you alert for a little while, but these benefits come at the cost of a shortened attention span and less patience – and often an unpleasant crash in the afternoon (which also has a lot to do with caffeine’s appetite-suppressing effects).

Like any other drug, caffeine induces artificial modifications of chemical systems evolved for specific purposes. There’s not necessarily anything harmful about that, but it’s also not a very effective long-term solution.

Still, there are a few hacks that can help you make the most of the attentional resources at your disposal. One of my favorites is to make a list, prioritized not necessarily in order of importance, but in descending order of willpower required – and interweaving small and immediate rewards along the way.

For instance, if it’s difficult to motivate yourself to hit the gym, you might make that your top priority as soon as you leave work or school – and follow it up with a little snack from your favorite restaurant. This keeps your mind focused on the reward, and teaches you to associate that reward with the volition-draining task. This is just basic associative (Hebbian) learning, but when you combine that technique with a list of tasks in descending order of willpower needed, you can often amaze yourself with how much you accomplish.

The flip side of this coin is the importance of keeping tabs on your remaining willpower, and being realistic about how much strength you have left. Just as you might decrease your running speed to finish the last few miles of a marathon, you may need to put off some arduous tasks until you’re more rested. This is where it’s crucial to learn the difference between lack of motivation and genuine mental exhaustion. Forcing yourself to perform when you lack the necessary resources tends to result in inferior performance – and will make you more susceptible to other temptations throughout the day.

By teaching yourself to gauge your own willpower, developing a clear sense of which tasks will require the most, and rewarding yourself for accomplishing those tasks, you’ll soon rocket to surprising new levels of productivity. I know because I’ve done it.


1. The word “psychic” doesn’t carry any paranormal connotation here; it just means “psychological,” as it did in the early 20th century. Why Baumeister et al. didn’t use a more modern scientific term is anybody’s guess. Throughout the rest of the paper, they use the term “executive function,” which makes more sense; but for this post, I’m largely sticking with “volition” and “willpower.”

One thought on “Limits of Control

  1. This was a fantastic read for me. I have obsessive-compulsive personality disorder, which is all about trying to achieve perfection and order, and tends to be parasitic on my self-control resources… Thanks for the concrete tips in this blog.

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