Medical scientists strongly endorsed the National Transportation Safety Board's recommendation Tuesday to ban nearly all use of cellphones and other portable electronics by drivers, saying the gizmos are just too distracting for the limited multitasking power of the human brain.

"I wholeheartedly support a ban on personal electronic devices, which provide an unprecedented degree of distraction that's very dangerous," said Dr. Lisandro Irizarry, chairman of the emergency department at the Brooklyn Hospital Center in New York.

"Everyone from teenagers to senior citizens is texting," he said in an email to msnbc.com. "It's very easy to get distracted, especially when driving, and end up in the ER."

The NTSB's recommendation specifically said so-called hands-free devices, like Bluetooth headsets, don't solve the problem and should be part of the ban. 

US calls for ban on in-car phone use ... even with Bluetooth

That sounds great to Dr. Marcel Just, director of the Center for Cognitive Brain Imaging at Carnegie Mellon University in Pittsburgh, a neuroscientist who has studied how using cellphones impairs driving ability.

"Use of cellphones while driving — handheld or not — is really a hazard, a threat to public safety," Just told msnbc.com. "It costs lives."

The problem is that people think they're better drivers than they really are, and so they believe they can multi-task behind the wheel. 

"When you're driving, it feels kind of automatic, so it feels like you're not doing anything, but it's not true," Just said. "Various parts of your brain are working on scanning the road ahead, maintaining your speed, maintaining your lane — all of those things are being done even when it feels like it's not.

Obviously, we can do two things at the same time," he said. "But the critical point is we can't do them as well at the same time."
Processing a conversation with another person consumes 37 percent of the energy that's normally allocated to driving, Just's research indicates. That's "a very, very large percentage that has serious consequences for safety," he said.

While carrying on a conversation in person with a passenger is distracting, "typically there isn't quite as much a social onus on continuing the conversation," he said.

In other words, a passenger who's in the car with you knows enough to shut up if you encounter a hazard on the road. But "with a person on the other end of a cellphone, they don't know to stop talking if something happens," he said. 

While he hasn't quantified the difference, Just said, he's convinced "it's worse with a cellphone."

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Updated at 4 p.m. ET: The government's transportation safety experts recommended Tuesday to ban all American drivers from using portable electronic devices — including cellphones, even if you use a hands-free device.

The recommendation, which isn't binding but which is likely to influence the decisions of Congress and state legislatures in writing  new safety laws, makes only two exceptions: You could still use GPS navigation devices, and you could use your cellphone in an emergency.

"No call, no text, no update, is worth a human life," Deborah Hersman, chairwoman of the National Transportation Safety Board, said at a news conference in Washington.

Besides calling for government action, the NTSB also urged consumer electronics manufacturers to figure out a way to "disable the functions of portable electronic devices within reach of the driver when a vehicle is in motion" while at the same time being able to turn themselves  back on in an emergency.

Jason Oxman, a senior vice president of the Consumer Electronics Association, said that as far as he knew, "nothing that would meet all of those parameters would exist today."

In general, Oxman  told msnbc.com, the focus should be on drivers' choices, not on "specific devices." He endorsed the NTSB's recommendations to the extent that they would regulate activities that take the driver's eyes off the road — “manual texting while driving, for example, you shouldn't be allowed to do it," he said. But he criticized the safety board's suggestion to disallow hands-free devices like Bluetooth earpieces.

"It may be that NTSB, in searching for a solution, is not aware of all of the technologies that exist today, and that is one reason we look forward to the opportunity to work with them," he said.

Safety advocates have long called for such a ban like the one the NTSB proposed Tuesday to reduce the phenomenon of distracted driving, which the National Highway Traffic Safety Administration says killed 3,092 people in 2010.

The NHTSA reported last week that about 20 percent of all drivers and 50 percent of drivers 21 to 24 years old admit to having texted while driving. Overall, more than three-quarters of drivers say they are willing to answer calls on all, most or some trips.

"People continue to make bad decisions about driving distracted — but what's clear from all of the information we have is that driver distraction continues to be a major problem," NHTSA Administrator David Strickland said last week in reporting the numbers. 

Scientists strongly endorse NTSB proposal

But similar studies linking cellphone use to poor driving have been challenged, most recently by researchers at Wayne State University in Detroit, who concluded last month that some earlier studies were seriously flawed.

The report, published in the journal Epidemiology, examined to earlier studies that examined crashes in which cellphone records showed that the driver had used a cellphone. Those studies "likely overestimated the relative risk for cellphone conversations," the researchers said, because they improperly assumed that the drivers were actually in motion when they were on the phone — in other words, they didn't factor in such so-called part-time driving.

Abstract: Cell Phone Use and Crash Risk: Evidence for Positive Bias

Only 10 states ban handheld devices right now, and 35 ban texting while driving.

The recommendation comes following the NTSB's investigation of an August 2010 accident in Gray Summit, Mo., involving a pickup truck, two school buses and several other vehicles. 

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The accident was blamed on the 19-year-old driver of the pickup, who sent or received 11 texts in the 11 minutes before the pileup, which killed two people and injured 38 others.

"That finding raises a red flag to all of us on the highways," Hersman said.

Full NTSB report on 2010 Missouri crash

The NTSB recommendation wouldn't cover GPS devices, but — if it eventually becomes law — it would ban using your phone for any reason, even with a Bluetooth headset or speakers. The only exception would be to call 911 in an emergency.

NBC News' Tom Costello contributed to this report from Washington.

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