Aside from paddy-wagon chauffeurs who couldn't care less, almost everybody who has ever taken the wheel of an automobile has suffered under the nervous nagging of the back-seat driver.
It is a pleasure then to report that a race car driver and a group of scientists have produced engineering data justifying a firm "shut up, you're making me nervous" the next time a back-seat driver is bothering you.
The race driver is Jay Chamberlain, 32, a winner at Le Mans in 1957 who has a medical record of 27 collarbone fractures to prove that he is a veteran at his sport.
He seemed a perfect guinea pig to 50 Northrop Corporation scientists anxious to test a telemetering system designed to register the emotional strain on astronauts in flight.
Thus on a rainy Thursday at Riverside Raceway, Calif., Chamberlain was wired up like a telephone switchboard. Electrodes were glued to his head, neck and chest, and even to corn plasters on his feet. They all led to instruments, crammed in the back of his Lotus XV racing car, on which his reactions would be recorded.
Chamberlain's first reaction as he watched the heavy rainfall was not to drive at all. "But when I saw all those men and equipment I didn't have the heart to call it off," he said.
He set out, reaching more than 150 mph as he twisted alone around the knots and turns of the track for an hour, in calm command of the situation. Then he took a passenger, William B. Harrison, a photographer, and again swept around the track.
Later, when Northrop analyzed its test information, an interesting pattern of tension was observed.
An electromyograph had registered Chamberlain's relative state of nerves on an oscilloscope. When the 'scope showed a generally smooth horizontal line, Chamberlain was calm, and that's what it showed (top left) while the driver circled the track at top speeds by himself.
But as soon as passenger Harrison got in, Chamberlain became more tense, the oscilloscope lines more jagged. Turns which Chamberlain had earlier taken calmly were now high-tension points. Midway in the run Harrison yelled into a recording microphone, "I can't see a thing!" and Chamberlain's tension line looked like saw teeth on the oscilloscope. Seconds later the passenger shouted, "Here comes that bad turn again!" The 'scope (center left) looked like the New York skyline at night.
Finally Harrison called, "Through the mud at 7,000 rpm!" and Chamberlain's anxiety (lower left) could hardly be contained on the oscilloscope. Chamberlain stepped out of his car after the last lap half shaking. "This was damn dangerous," he said.
The danger, the engineers saw, was more at Chamberlain's elbow than on the roadway. To which the driver of the family sedan on Sunday is entitled to say: "You're telling me?"