Bob Moore writes:

Head and body should remain perpendicular to the floor of the
cockpit. This comes naturally if the turn is coordinated.

Interesting. When you learn to ride a motorcycle, you're taught to keep your
head normal to the horizon in turns ... because turning your head with the
bike as you lean into a turn results in disorientation.

Perhaps pilots would be less prone to disorientation if they kept their heads
normal to the horizon, even in turns (for instrument flight, this would mean
keeping one's head level with the horizon of the attitude indicator).

I note from in-cockpit videos of aerobatic pilots that they keep their heads
level with the horizon, not level with the aircraft.