I recently received a children's book catalogue that I've been getting for years and have always liked. Like most book catalogues, it includes toys and goodies for mothers as well. This time, it included a sort of sliding and riding toy, and here's what the description said: "..it... assists children in balance, coordination, and vestibular stimulation, all skills now being linked to reading and writing readiness. The vestibular system is what switches on our entire brain and opens up our sensory channels for more efficient learning." Passing lightly over the fact that vestibular stimulation is not "a skill", let's look at the accuracy of this statement. I happen to have done my Ph.D. thesis on a matter related to the vestibular system, so I have something to say here.
Everyone has a vestibular system, and it's one of the first sensory systems to reach a mature level in the course of early development. Lying in close proximity to the inner ear, inside the skull, the vestibular system consists of two parts. One of these responds to the pull of gravity and provides information about the position of the head relative to the horizontal plane of the earth's surface. The other one responds to movement of the head and gives a strong sensation of rotation in one direction or another. (But.... This only works when you're accelerating. If you reach a constant speed and stay at it, you will feel as if you're sitting still when you're rotating at 60 RPMs. And when you slow down it feels as if you're rotating the opposite way. The system is very sensitive but not very accurate.) A major function of this system is to help us figure out whether something we're looking at is moving, or whether we're moving in relation to the object, or whether both those things are happening at the same time. We can manage without much vestibular information, though, or astronauts would not be able to do complicated tasks in space, where there is no gravitational pull to stimulate the first part of the vestibular system (the utricles and saccules, if you really want to know). And if we get the wrong kinds of vestibular stimulation-- nausea is the result.
Stimulation of the vestibular system also affects other parts of the nervous system. Crying babies are often most easily soothed by repetitive vestibular stimulation like rocking, walking, or jiggling. When mothers carrying babies stop to talk to each other, we often see both of them start to jiggle as they stand, a pre-emptive effort to keep the babies happy. Researchers have even calculated the wave form of the motion most effective at soothing babies---- not that this is of much practical use, because we can't easily figure out how to move in a way that duplicates that wave form.
Can't think what a wave form has to do with rocking the baby? Well, consider another kind of vestibular stimulation and its wave form: a real ocean wave. You're on a boat, and as waves go by they lift the boat--- they lower the boat--- they lift the boat-- they lower the boat-- are you turning green yet? How quickly you get seasick will depend in part on the wave form, which means how frequent the shifts are, how gradual or sudden they are, and how high or low the boat goes. Some wave forms may make it hard to stay on your feet, but won't make you sick. Others tickle your autonomic system almost at once, by stimulating the vestibular system. (And they don't stop tickling it when the wave stops. My husband, who just went on a sailing race from Baltimore to Norfolk, says that after 60 years of sailing he still feels as if the land heaves when he gets off the boat.)
One thing that's poorly understood about the development of the vestibular system is that most young children love play that involves vestibular stimulation. Kids' playgrounds are practically temples of vestibular activity, with swings, slides, merry-go-rounds all dedicated to maximum vestibular stimulation. But somewhere about puberty many of us find we're queasy on these things, and much more so on rollercoasters. However, some adults continue to get a great kick out of their vestibular lives.
The upshot is that different kinds of vestibular stimulation have different effects on different people at different times in their lives. Some vestibular stimulation can soothe babies, and if they're calm and not crying they can pay more attention to other sensory stimulation and learn from it. Older children can have a lot of fun with their choice of vestibular activities, and having fun can certainly be a pathway to confidence and interest in learning. But switching on the brain? No, sorry, the brain is already switched on. Opening sensory channels? Vestibular system activity provides information to compare to visual input, and that makes us more accurate about judging distance and movement of objects, but that's not the same thing.
There's no developmental magic in vestibular stimulation. That toy looks like a whole lot of fun, and that's really what it's all about. But, parents-- please don't get sold a bill of goods about providing vestibular stimulation, as if it's the solution to all problems. Even if it were, you wouldn't need to buy it. Your children make it for themselves, and if they don't, you are probably doing it for them already.