Happily! It's not complicated, actually.

So imagine you're playing tennis. You will be trying to estimate where the ball is going. What information do you have? Well, obviously your eyes, but your ears will also help you because you can hear the ball swooshing through the air (and for a veteran player, hearing the way your opponent hit the ball is invaluable info). So how do you combine these data into one coherent picture? Well, scientists found out that we take the information from both senses and use them proportionally to create a mental representation. The proportion is determined by how reliable you think that sense is. In our example, we'd probably rely more on our visual sense, so maybe 70% visual and 30% audio. This all happens subconsciously in the brain. This process is called bayesian (because of the weights we assign to the senses) integration (because we combine both senses, which makes our model of the situation more accurate).

Here's that principle in action. Red could be visual, blue aural. Green is when we integrate them. The cool thing about this is that we reduce variance by doing this: Our senses have a harder time tricking us! And that's pretty cool.

So what somebody else then tried was seeing if kids did that, too. And it turns out they don't, it's not something we're born with - we learn this! What kids do is similar, but not quite as good: Instead of combining both senses, they rely on either one or the other, but they switch it around based on how reliable that sense is. So if you played a 100 balls, they'd rely on the eyes only for 70 balls and on their ears for the other 30.

Now what we're doing is looking at how this impacts augmented senses. We have a belt that always vibrates in direction North. We then sit people on a rotating chair. They are blindfolded and have headphones on, so the only thing that tells them they are moving is their vestibular (your sense of balance) sense, and this belt. We're wondering what strategy people use to combine the vestibular sense with the belt.

Actually, we already know that they use the same strategy kids use (which might also mean that the integration thing is hard-wired between each sense, not very flexible). But what we're now trying to do is find some activity in the brain that might help us find out more about this.