Equilibrium signal. An incoming sign received when the body's head is suddenly accelerated, decelerated, or tilted.
Usage: Though we instinctively keep our head stabilized, we enjoy accelerating, dropping, and spinning it as well, e.g., in such sports as auto racing, skiing, sky diving, and surfing. Stimulation of motion sensors in our inner ear is not only pleasurable, but diverts attention away from today's concerns and tomorrow's fretful worries. In part, this is because older centers of the brain's basal ganglia and cerebellum are engaged, centers in which there is no tomorrow, but only the present moment in time.
Anatomy. Stimulating accelerometers of the inner ear diverts our attention from anxiety and apprehension about the future. The inner ear's utricle and saccule are sensitive to linear acceleration and to gravity, while its three semicircular canals are sensitive to angular and rotational acceleration. Rotation upsets the normal circulation of fluid in the ear's balance loops to make us feel dizzy (Pool 1987:69).
Consumer products I. 1. We consider the illusion of speed thrilling, and find roller coasters (which only kill one or two people a year in the U.S. [Poundstone 1990:124]) scarier than automobiles (which kill 50,000 a year [Wright 1990:263]). The fastest roller coaster in the world (in Gurnee, Illinois) averages only one mile faster than 65 mph, the speed limit of some interstate highways. (N.B.: The average adult coaster has a top speed of only 38 mph [Poundstone 1990:126].) 2. We scream loudest during the initial plunge, which triggers our innate fear-of-falling reflex, as we grasp the bar in front of us tightly with a power grip. We enjoy Magic Mountain's Viper, in Santa Clarita, California, which, from its highest point 188 feet above the earth, carries our head upside-down seven times at speeds up to 70 mph (McFarlan 1990:92).
Consumer products II. To maximize the fear of falling, many take their heads aboard Magic Mountain's FreeFall ride. After waiting in line for up to 45 minutes, their heads drop for 2.5 seconds 90 feet straight down a steel track (Poundstone 1990:131-32).
Consumer products III. After rocking for 70 minutes in rocking chairs, nursing home patients diagnosed with dementia showed up to a one-third reduction in signs of anxiety and depression. According to University of Rochester geriatric nursing researcher, Nancy Watson, "You could see immediately by their faces that they were enjoying themselves."
Courtship. Not only do we rock babies from side to side, but also the adults whom we love as well (see LOVE SIGNALS IV, Hugging).
Freewheeling. Our enjoyment of free body movements through space may be innate (Thorndike 1940).
Neuro-notes. The inner ear's vestibular system, innervated by cranial nerve VIII (vestibulocochlear) senses positions and movements of the head in space.