You've been driving behind the same car for ages, and you're stoked because you see that there's a passing lane ahead.
Unfortunately, the moment you get to the passing lane the car in front of you speeds up so much that you can't safely pass them; so irritating!
Apparently, this isn't just all down to bad drivers, even though it can sometimes seem like the guy in front of you is trying to prevent you from reaching your destination.
Science tells us that our it's all about our brain's perception of speed. Narrow roads increase our perception of speed, and wider roads decrease that perception.
What does that mean?
Naturally, people speed up when the road widens and slow down when it's narrow; known as risk homeostasis.
This makes it seem like people are playing cat-and-mouse with you, but most of the time they're 'probably' not...
Researchers also found that vision and noise influence people's perception of speed. Vision deteriorates with age, so older people tend to drive slower to compensate for their lack of vision.
Noise can be used to estimate speed, so sometimes people with noisy older cars sometimes think they're travelling faster than they actually are.
So the verdict is that even though it's hella annoying; there are a bunch of factors that go into why people are driving slowly. But sometimes people are just crappy drivers.