It’s finally time to solve the mystery of why you get carsick when you’re trying to read while in motion, but your significant other is able to do it just fine (so unfair!).
Author Dean Burnett recently explained how it works on NPR. The long and short: The thalamus is the part of the brain that interprets sensory signals. Due to that and the “balance sensors” in our inner ears, we’re able to know when we’re in motion, if we’re upside down, etc.
When your eyes focus on reading, however, you’re telling your body that you’re still. But then your sensory signals are sending mixed messages because you’re also moving. Here, let’s let Burnett explain it:
So what’s happening there is the brain’s getting mixed messages. It’s getting signals from the muscles and the eyes saying we are still and signals from the balance sensors saying we’re in motion. Both of these cannot be correct. There’s a sensory mismatch there. And in evolutionary terms, the only thing that can cause a sensory mismatch like that is a neurotoxin or poison. So the brain thinks, essentially, it’s been being poisoned. When it’s been poisoned, the first thing it does is get rid of the poison, a.k.a. throwing up. And as a result — so, like, as soon as the brain gets confused by anything like that, it says, oh, I don’t know what to do, so just be sick, just in case. And as a result, we get motion sickness because the brain’s constantly worried about being poisoned.
That nauseous feeling is nothing more than your body trying to rid itself of a “poison.”
And as to why some people experience this more than others, Burnett says their really is no reason. He chocks it up to a simple “quirk of development.”
So, there you have it. Evolution can be so cruel.