Why does your brain never run out of problems?

How can you know if you’re making progress solving a problem, when you keep redefining what it means to solve it?

Why do many problems seem to stick around, no matter how hard people work to fix them? It turns out that a quirk in the way human brains process information means that when something becomes rare, we sometimes see it in more places than ever.


For example, I consult in the Emergency Management space, helping clients manage emergency related risks for large commercial infrastructure. Initially, when taking on a new client there are generally some outstanding issues that require solutions. In layman’s terms I usually hit the ground running.

Over time, as an emergency management program takes effect, emergency related risks are reduced. Occupants and management of these large facilities realise they are encountering less fire alarms, emergency exercises have rehearsed a wider range of emergency scenarios and people start to realise that many of the challenges of the past have been taken care of.

However, what has been my experience, and also recently highlighted by psychological research conducted by David Levari PhD from Harvard University Psychology Department, that when faced with relaxing and considering the problem at hand solved (emergencies, in my case) or continuing to define what constitutes an emergency that requires a solution; the latter is most people’s choice.

You can probably think of many similar situations in which problems never seem to go away, because people keep changing how they define them. This is sometimes called “concept creep,” or “moving the goalposts,” and it can be a frustrating experience. How can you know if you’re making progress solving a problem, when you keep redefining what it means to solve it?

To study how concepts change when they become less common, Levari brought volunteers into his laboratory and gave them a simple task – to look at a series of computer-generated faces and decide which ones seem “threatening.” The faces had been carefully designed by researchers to range from very intimidating to very harmless.

As the research team showed people fewer and fewer threatening faces over time, they found that the participants expanded their definition of “threatening” to include a wider range of faces. In other words, when they ran out of threatening faces to find, they started calling faces threatening that they used to call harmless. Rather than being a consistent category, what people considered “threats” depended on how many threats they had seen lately.

This kind of inconsistency isn’t limited to judgments about threat. Levari’s team has conducted similar tests using moral and ethical situations, coloured dots on a page. Levari even began offering cash prizes to entice people to remain consistent in their judgements – which failed.

So, as the context changes, so do the boundaries of your categories. The brain likes to make comparisons

Research from cognitive psychology and neuroscience suggests that this kind of behavior is a consequence of the basic way that our brains process information – we are constantly comparing what is front of us to its recent context.

It turns out that for your brain, relative comparisons often use less energy than absolute measurements. To get a sense for why this is, just think about how it’s easier to remember which of your cousins is the tallest than exactly how tall each cousin is. Human brains have likely evolved to use relative comparisons in many situations, because these comparisons often provide enough information to safely navigate our environments and make decisions, all while expending as little effort as possible.

One potential strategy: When you’re making decisions where consistency is important, define your categories as clearly as you can.