What causes motion sickness? Here’s how to reconcile the mismatch in what your senses are telling your brain

My first experience with motion sickness was as a college student, standing on the back of a marine research vessel looking at interesting things dredged from the seafloor off the California coast. It was a day trip, the weather was good and the sea was calm. I was unaware of the boat’s gentle pitching and rolling, instead concentrating on the mud and organisms on a table in front of me.