Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Ryan on 10/12/2009 09:30:02
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Ryan asked the Naked Scientists:
Love your show!
I am a motion sickness sufferer. But why is it that when I drive, I never suffer with motion sickness, yet, asĀ a passenger I suffer really badly?
What do you think?
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My Daughter does that to.. I often think it is because she is occupied both physically and mentally when driving and can control the car so she feels more comfortable... Someone may come with a more scientific explanation...
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I think when you intentionally move your body, your brain is coordinated with the signals from the nervous system. If there is unintentional movement of the body, like a passenger, the brain is not coordinating the imput, making you suffer with motion sickness...
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There is also an effect from peripheral vision. When you drive you are focussed on the road ahead. But as a passenger, movement in the peripheral vision plays a bigger role. If you are suscepible to motion sickness it is definitely worse in the back of a car than the front for instance.
The theory is (I believe) that this has evolved because there are mixed signals reaching your brain from your balance sensors (inner ear) and visual sensors and that a possible cause is a neuro-toxin, hence the evolutionary advantage in this making you sick. I think this is entirely speculative, but makes sense. Pets are often car sick too.
I like sailing but can get seasick. It is much better on deck looking at the horizon than down below. Interestingly I have found that I have got much better over the years so I guess that you can train yourself out of it eventually.
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The theory goes that motion sickness occurs when there is a disparity between anticipated movement and actual movement, as reported by the balance system, eyes, muscle proprioceptors and so on.
The driver of a car is therefore at an advantage because he has his eyes glued on the road ahead and also, being in control of the car, knows what movements are going to be made in due course. Consequently he can anticipate quite well the future movements the body will be experiencing. Passengers (including back seat drivers!) are not in this privileged position and hence they do experience a disconnect between perceived and anticipated movement and this provokes nausea.
Why the brain decides that throwing up is the best solution to the confusing barrage of sensory information I have no idea...
Chris
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I will get car-sick as a passenger if I try to read a book/magazine for more than a minute or so - but otherwise I'm fine. Trains and planes present so such problems for me (though I wouldn't contemplate even trying to read on a bouncy London Underground train!).