We’ve all been there – the directions sounded so clear when we were told them. Every step of the journey seemed obvious, we thought we had understood the directions perfectly. And yet here we are miles from anywhere, after dark, in a field arguing about whether we should have gone left or right at the last turn, whether we’re going to have to sleep here now, and exactly whose fault it is.

The truth is we shouldn’t be too hard on ourselves. Psychologically speaking giving good directions is a particularly difficult task.

The reason we find it hard to give good directions is because of the "curse of knowledge", a psychological quirk whereby, once we have learnt something, we find it hard to appreciate how the world looks to someone who doesn't know it yet. We don’t just want people to walk a mile in our shoes, we assume they already know the route. Once we know the way to a place we don't need directions, and descriptions like "its the left about halfway along" or "the one with the little red door" seem to make full and complete sense.

But if you've never been to a place before, you need more than a description of a place; you need an exact definition, or a precise formula for finding it. The curse of knowledge is the reason why, when I had to search for a friend's tent in a field, their advice of "it's the blue one" seemed perfectly sensible to them and was completely useless for me, as I stood there staring blankly at hundreds of blue tents.

This same quirk is why teaching is so difficult to do well. Once you are familiar with a topic it is very hard to understand what someone who isn't familiar with it needs to know. The curse of knowledge isn't a surprising flaw in our mental machinery – really it is just a side effect of our basic alienation from each other. We all have different thoughts and beliefs, and we have no special access to each other's minds. A lot of the time we can fake understanding by mentally simulating what we'd want in someone else's position. We have thoughts along the lines of "I'd like it if there was one bagel left in the morning" and therefore conclude "so I won't eat all the bagels before my wife gets up in the morning". This shortcut allows us to appear considerate, without doing any deep thought about what other people really know and want.

“OK, now what?”



This will only get you so far. Some occasions call for a proper understanding of other people's feelings and beliefs. Giving directions is one, but so is understanding myriad aspects of everyday conversation which involve feelings, jokes or suggestions. For illustration, consider the joke that some research has suggested may be the world's funniest (although what exactly that means is another story):