If you fly on a commercial airliner and listen to the safety demo (most people don’t listen, of course), you might wonder why the video or crew instructs you how to use the seat belt. The instructions have been the butt of many a comedian’s joke (“In case you haven’t been in a car since 1965,” as Jerry Seinfeld quips in one of his stand-up routines).

But that’s precisely the problem. You have been in a car lately; in fact, you probably unbuckled a car seat belt an hour before boarding your plane, and may have done so dozens of times in the days before your flight.

But car seat belts work differently from the “lift the buckle” way that airplane seat belts release. And believe it or not, in a panicked emergency, passengers who might not be thinking clearly because they’re disoriented or mentally incapacitated — barely awake before a 6 a.m. takeoff, jet-lagged after a long flight or under the influence of Ambien or alcohol — have been known to reach to the right or left near their thighs, as you would in an automobile, trying to push a seat belt release button rather reaching for their laps and lifting a flap. In other words, previously established “muscle memory” works against you in a crisis.

How do I know this? Not only have flight attendants told me it happens, but I, someone who travels thousands of miles a year, have done the same thing at the end of a 12-hour flight with little sleep as I attempt to release the seat belt.

Because every second counts when evacuating a plane, any confusion could cost lives. In fact, pilots are known to practice muscle memory in the cockpit, touching levers and fingering buttons before takeoff, so that in an emergency they will remember where the controls are located and be able to act quicker.

Something to think about the next time your nose is buried in a newspaper during the safety demo.

George Hobica is founder of the low-airfare listing website Airfarewatchdog.com.