DETROIT – The president of the United States suddenly drops by your office for an impromptu chat. Your cell phone rings. Do you answer it?

For many people, the answer is yes, says Paul Green, a research professor at the Human Factors Div. of the University of Michigan Transportation Research Institute.

“Are you expecting to talk to someone more important?” jokes Green.

For whatever reason, the ringing cell phone is an irresistible siren’s call for many folks no matter what the situation, whether it’s conversing with George W. Bush or driving down a treacherous road, says Green during his presentation at the User Interface Challenges session of Tuesday’s Convergence conference.

“The behavior to answer a ringing phone and engage in a conversation is so ingrained that it is extremely unlikely that any amount of public awareness, education or training will alter that highly reinforced behavior,” he says.

Such single-mindedness, along with telematics-related distractions Green defines as “inattention blindness” (so engrossed in a cell phone conversation you aren’t looking where you’re going) and “cognitive capture” (taking your mind and eyes off the road to dial a phone, program a navigation system or related activity) in a large number of studies have been proven to cause crashes.

Making matters worse, telematics-induced crashes frequently happen in the most avoidable of circumstances, when weather is clear, traffic is light and road surfaces are dry, he says.

A possible solution to such distraction issues is what Green calls a “workload manager.”

It’s a device that limits non-essential driver information and telematics activity if it determines a driver is distracted or overloaded with tasks.

Some rudimentary versions already are installed on current Saab and Volvo models in the U.S., and at least a half-dozen auto makers are developing workload managers for future products, Green says.

In its simplest form, a workload manager postpones a driver reminder about an oil change during a torrential downpour.

However, more advanced versions might monitor steering-wheel inputs and location via a global positioning satellite system and block an incoming phone call while a driver is making a turn in an intersection.

Already most navigation systems are equipped with lockouts that prevent programming while driving.

Green says workload managers are divided into four categories: those that monitor the driving situation, driver input, vehicle performance and response and driver state.

For instance, he says workload managers that monitor the driving situation could determine how hazardous driving is according to traffic data or slipperiness of the road surface or even crash data for a specific segment of highway.

Driver input workload managers determine distraction by erratic steering or throttle inputs, while those that monitor vehicle performance might red flag lane departures or weaving.

The ultimate workload monitor would collect driver eye fixations, because the key indicator a driver is distracted is when he or she isn’t looking at the road, Green says. However, he adds there are major technical challenges to cost-effectively installing such devices in vehicles.

Another challenge: Many driver’s resent the idea of their own car telling them what they can and cannot do under any circumstances, even when they’re being rude to the president.