We use simple rules called heuristics to try to make sense of the world around us. Those heuristics work because our world is structured, it has regularities patterns and detecting those patterns can often help us make very good decisions but sometimes the patterns we detect can lead us astray.

A face on Mars

On July 31, 1976 the US space agency NASA released a photograph of Mars. At that time the Viking 1 Orbiter was circling our planetary neighbor snapping photographs of landforms to help identify a landing location for a space probe. Usually its photos attracted little attention from the public, but this photograph drew people’s attention.

NASA’s official photo caption said: “the picture shows eroded mesa-like landforms. The huge rock formation in the center which resembles a human head is formed by shadows giving the illusion of eyes, nose and mouth”. To a geologist the image looks like an eroded mesa, but to all the rest of us it looks strikingly like a human face.

Over the succeeding years the face on Mars generated no end of controversy. To many people it was a sign of an ancient alien civilization on another planet, other people thought it had religious significance and still others considered it clear evidence of a conspiracy that reached into the highest levels of NASA.

The scientists argued that this image didn’t show a face, it just showed a rock formation that had been shaped by random geological processes, but that didn’t stop the popular belief in a face on Mars which continued for decades afterward. So, why did so many people believe in an alien civilization on Mars?

We are set up to look for meaning

Why do people believe in astrology, extrasensory perception and many other pseudo-sciences? Why are people readily taken in by financial scams that promise them impossible returns at minimal risk? These may all sound like fringe beliefs to you, the sorts of ideas that other people believe in.

I want to emphasize though that we are all susceptible to beliefs of this sort, we are set up to look for meaning even when there’s nothing but randomness. So let’s begin with some simple definitions: What is randomness and why does it matter for decision-making? Randomness means that you can’t predict the future from the past.

A simple way to generate a random sequence is to flip a standard coin 20 times. You can diligently record the outcomes of the first 19 flips looking for patterns in that sequence, but no amount of analysis will ever help you predict what will happen on the 20th flip. There will always be equal chances of a head and a tail.

The process of flipping a coin leads to a sequence of events that are unpredictable. Let’s now change from a random process to a nonrandom process. Suppose that you instead asked a friend to generate a sequence of 20 hypothetical coin flips by writing them down without using a real coin. If you could study the first 19 flips and your friends sequence you could indeed improve your probability of guessing the 20th.

Nonrandom processes are predictable

How? It turns out that people show a particular bias when trying to behave randomly, they switch too much, they try to make short sequences of events seem random, they introduce too many patterns that alternate between events. Look at the 19th flip! If your friend wrote tales just heads or vice versa. Because your friend is human and carries the same biases of the rest of us looking at their past behavior can improve your predictions.

Nonrandom processes are predictable at least in principle. I emphasize this distinction because the idea of randomness is closely tied the idea of information. A process that is completely random carries no information about the future and it doesn’t tell us anything that helps us make better decisions, but a nonrandom process contains information.

If we know what to look for we can learn from that information and make better decisions in the future. So what sort of processes are random and what sorts of processes are nonrandom? That’s the key question and I’ll only answer it halfway for now. Think about sequences of events in the natural environment: when we see lightning we can predict it will soon hear thunder, when we drop a stone to the top of the hill we can predict that all role downward.

Events in the natural world are predictable because they are generated by nonrandom processes, the laws of physics buying these different events together into meaningful sequences. Our interactions with other people are also nonrandom even if it might sometimes seem otherwise. There’s a history of all of our relationships when we interact with someone we might build trust or break it.

Sometimes  the thunder doesn’t come

We might send signals a friendship or hostility those different events can create social connections. We even call good friends dependable because we can predict how they’ll behave toward us. Just because something is nonrandom that doesn’t mean that we can know everything or can predict the future perfectly.

Sometimes we see lightning and then the thunder doesn’t come, but with careful observation of a nonrandom process our predictions about the world get better over time. By anticipating the seasonal migrations our ancestors became better hunters, by observing how different crops grew in different soils they became better farmers.

In every case that you can imagine learning about patterns in nature and in other people made our ancestors more likely to survive and prosper. It’s no wonder then that we’ve evolved to be really really good at finding patterns, our brains look for patterns automatically without any conscious effort and even if there’s no pattern to be found.

A few years ago my colleagues and I did a simple experiment we showed people a random sequence of circles and squares. Even though the sequence was completely random people’s brains were continually trying to find patterns in that sequence. As people start to perceive a pattern, say after seeing three squares in a row the activity levels in the region of the brain called the prefrontal cortex would decrease with each successive event that fit that pattern.