It's a truism of devastating obviousness that we tend to prefer the easy option over the difficult one. Terrible choices of almost any size – from not going to the ­dentist to causing the sub-prime mortgage crisis – can usually be traced back to the fact that doing things differently would have taken more effort. Sure, there may be other, subtler explanations for humanity's reliable tendency towards wrongness and fiasco, but I can't be bothered to think of any. Like everyone else, I'm taking the easy option, thereby providing evidence in ­support of my point. Thus I win.

Even if it's a truism, though, it's only relatively recently that ­psychologists have come to grasp how deeply this preference for ease ferrets into our brains, manifesting itself not just as a liking for physical sloth, but for mental laziness, too. They call this "cognitive fluency": the idea that if something is easy to think about, we're far more likely to think it preferable, more important or true. One study suggests that people think of recipes, or lists of tasks, as easier if they're printed in a clearer font. Another suggests that hostility ­towards immigrants may be partially explained because it's more taxing to conceive of, say, a person from ­Algeria who lives in France than a French person living in France. The well-known "availability bias" makes us more afraid of threats we can vividly picture, no matter how unlikely. (Did you know you're 30 times more likely to be killed by a falling piece of aircraft than in a shark attack?) An academic study of the anonymous confessions site grouphug.us concluded that people became more candid when a more legible redesign was intro­duced. And companies with easier-to-pronounce names, the Boston Globe reported recently in a round­up of cognitive fluency research, fare ­better on the stock market.

This makes good evolutionary sense, of course: our brains have ­developed to conserve our energies for when we need them to survive. This may be why it's so hard to feel motivated to go jogging: exercise for its own sake would have been insane in a world in which you got all the workouts you needed just feeding yourself and escaping wild animals. A fondness for the familiar, similarly, is eminently ­understandable. As the late psychologist Robert ­Zajonc liked to say, "If it's familiar, it hasn't eaten you yet."

There's an upside to this ­tendency to idleness, though: ­cognitive ­fluency's opposite, ­"disfluency", prompts us to think things through more carefully, and can be harnessed to prompt focused thought. Those same font researchers found that printing something in a difficult typeface caused people really to ­engage with the content; far more gave the correct answer to the ­question "How many animals of each kind did Moses take on the ark?" (Answer: none.) The novelist Colum McCann prints off his drafts in eight-point Times New Roman, in order to peer at his words with fresh eyes and a more rigorous mind.

And yet I can't help feeling ­dispirited. It's agonising enough to consider the great opportunities we miss in life as a result of crippling fear, or lack of talent, or appalling bad luck. How much worse is it to think of all the roads not taken because just thinking about them in the first place took a little more effort? The only solution, presumably, is to be constantly on the alert for lazy thinking. Which is, in itself, mentally tiring. Yes. It's awkward.

oliver.burkeman@theguardian.com