Regarding the issue of hands-free cell phones while driving versus having a conversation with a passenger, studies have shown that having a conversation with a pasenger is much less distracting. Cell phone conversations are often more focused on something (business, what to pick up at the grocery store, etc.), while conversations with a pasenger are generally more casual. ... and timed better (see below).
Also, having the person in the car with you allows him to assess the driving situation (either consciously or subconsciouly), and the pasenger will adjust the intenisty of the conversation accordingly. A person at the other end of a cell phone conversation doesn't know when to tone it down. Here's an example I'm sure many of us have faced...
You need to pull out into busy traffic on a busy road at night in the rain or in rush hour traffic. ....or maybe driving next to a jersey wall in a narrow construction zone. Many of us will even turn down the radio in an intense driving situation like this just so we can concentrate more. Now imagine having a cell conversation with your boss at that time, and he is yelling at you and asking about the 3rd Quarter sales figures. That certainly won't help your driving situation. Even if that same boss was riding in the car with you, he would most likely have the instinct to tone down or stop that conversation, even if only temporaily, to give you a chance to get into a safer driving situation. A boss (or whoever) at the other end of a cell phone has no idea of the road situation.
Here is a summary quote from a University of Utah study on it:
"A 2004 University of Utah simulation study that compared passenger and cell-phone conversations concluded that the driver performs better when conversing with a passenger because the traffic and driving task become part of the conversation. Drivers holding conversations on cell phones were four times more likely to miss the highway exit than those with passengers, and drivers conversing with passengers showed no statistically significant difference from lone drivers in the simulator.
A study led by Andrew Parkes at the Transport Research Laboratory, also with a driving simulator, concluded that hands-free phone conversations impair driving performance more than other common in-vehicle distractions such as passenger conversations.
" It seems there are 2 factors at play in cell conversations versus conversations with passnegers: 1.) The nature of the conversation, and/or 2.) The timing of the conversation.
The nature and/or timing of conversations is usually more distracting on a cell phone conversation than with a passenger.
Glenn
<message edited by Glenn1234 on Tue, 11/23/10 3:55 AM>