Earlier quoted context omitted.
Ah, it's from a simulator, where you don't get the benefit of your own body responses - no inner ear cues, no tactile feedback, no proprioception feedback. People driving cars in simulators also do worse than in the real thing - a simulated car doesn't have all the ways a car tells you that you're driving close to the envelope.
Not exactly. "Simulated Instrument Flight Conditions" usually means that your instructor has you put on a view limiting device [1] so that you can only see your instruments and not outside the aircraft. One of the reasons it's done this way is to teach you to ignore inter ear cues and trust your instruments. Your inter ear senses acceleration, not absolute motion. Couple that with the centrifugal force during a turn…
I guess what I was getting at was not so much that you could survive with your inner ear, but that you get a lot of feedback from a vehicle that you don't in a simulator. That's not relevant to this study if they didn't use a simulator, though...