Hire car syndrome

BMJ 1995; 310 doi: (Published 20 May 1995) Cite this as: BMJ 1995;310:1337
  1. Bernard Dixon

    Getting accustomed to an unfamiliar hire car takes a little time. Some of the controls are in the wrong place. The clutch bites too early or too late as you raise your foot. The accelerator is either more or less sensitive than the one in your own vehicle. And so on.

    You really have to concentrate hard on what you are doing. Taking off from the garage, you are likely to change gear less smoothly than usual, grope for the radio switch, and inadvertently switch on the wipers. Yet a few hours later, the car feels perfectly normal. You are back on automatic pilot.

    Two weeks afterwards, you slip back into your own car seat. Now this one feels peculiar. Indeed (in my experience, at least) it's even odder than the task of getting used to a hire car. The problem is more than just the angle of the foot pedals or the movement of the gear lever. There is an additional sensation of disorientation—not unlike that experienced when walking down a stationary escalator. You may have driven thousands of miles in this selfsame car. For a while, nevertheless, it feels even more weird than a totally unfamiliar vehicle. The automatic pilot, conditioned over thousands of miles in this very seat, takes a while to resume command. Why?

    I've puzzled over this question many times in the past. But it hit me particularly forcibly recently when, by courtesy of a Colles' fracture, I was unable to drive at all for six or seven weeks. This was the first time for many years that I had been off the road for so long. Nevertheless, there was no funny feeling, no disorientation at all, when I took the wheel again. It was just as though I had been driving only yesterday.

    This confirmed that the discomfiting sensation on returning to your own car after a spell in another one is nothing to do with the period away in itself. The strangeness is determined solely by the period of acclimatisation to the other car and your subsequent readjustment to more familiar surroundings. What is decidedly odd is that the effect occurs even after as little as two or three days in a hire car—a trivial amount of time as compared with the years you may have spent in your own motor.

    Is this phenomenon of interest and potential value to neurophysiologists? I believe it should and could be, respectively. The stationary escalator effect is apparently the result of a cerebral battle between the messages coming from your eyes and your organs of balance and gravity. What you see tells you that you should be moving in a familiar way. Your semicircular canals, saccule, and utricle tell you something different. The visual images win, but only after a struggle.

    Now consider the hire car syndrome, and the opportunities it presents to investigate more thoroughly the hierarchy of senses. By switching volunteers between appropriately designed vehicles (or simulators?) investigators could assess the contributions made to those funny feelings by features such as the operation of the controls, the visual images experienced from the driver's seat, the overall physical framework of the vehicle, and the movement and road handling of the car.

    The results of such a study might have implications for car design; but does anyone out there find the idea itself at all interesting?—BERNARD DIXON, European contributing editor, Biotechnology