The Nervous System and Sensory Illusions
The senses that matter in flight
The central nervous system integrates vision, hearing, the vestibular system and somatosensory input. Vision dominates, but peripheral vision detects motion while central vision gives detail. At night, use off-centre viewing to exploit the rods, which are more sensitive but colour-blind and slow to adapt. Dark adaptation takes about 30 minutes, and bright light destroys it quickly.
The vestibular system and its limits
The semicircular canals sense angular acceleration, not steady rotation, and are easily fooled by prolonged turns. The otolith organs sense linear acceleration and gravity but cannot tell them apart. This produces the somatogravic illusion (acceleration feels like a nose-up attitude) and the leans (a false sense of bank after a prolonged turn). Somatosensory cues from seat pressure add further misleading information. Hearing matters for warning tones and communication; noise-induced hearing loss is permanent, while temporary threshold shift recovers.
Traps in questions
The classic trap is asking what the pilot should believe during an illusion: trust the instruments, not sensations. Another is confusing which organ senses which quantity: canals sense rotation, otoliths sense linear acceleration and tilt. Also remember that the leans are corrected by reference to instruments, not by 'trusting your seat'.
Worked example
After a sustained turn, a pilot rolls out and feels a turn in the opposite direction. The canals are signalling the stop of rotation as if it were rotation the other way. Rule of thumb: in instrument conditions, believe the attitude indicator and cross-check with other instruments.