Which organs are stimulated to cause somatogravic illusions?

The stimulation of the otolith organs is directly responsible for causing somatogravic illusions. The otolith organs, which include the utricle and saccule, are part of the vestibular system and are crucial for the perception of linear acceleration, changes in head position, and gravitational forces. When a person experiences rapid changes in motion, such as during acceleration or deceleration in an aircraft, the otolith organs detect these changes and send signals to the brain regarding the body's orientation and movement.

Somatogravic illusions occur when these signals are misinterpreted, often leading to a false perception of the body's position or movement, such as feeling a sense of upward motion during acceleration. This can occur even when the actual motion does not match the perceived sensation, resulting in disorientation.

In contrast, while the semicircular canals also play a significant role in detecting rotational movements, they are not involved in the specific sensations associated with linear acceleration that lead to somatogravic illusions. The auditory receptors and hair cells, which are involved in hearing and sensing fluid motion, respectively, do not contribute to these particular illusions at all. Therefore, the otolith organs are the key structures responsible for the phenomenon in question.