I hate to see products like these promoted because the creators are making bloodmoney.
Cell phones are not dangerous because the driver was looking at his phone or playing with the buttons when he had an accident. They are dangerous because they encourage your mind to wander. Most people's brains are really not good at multitasking. (Try patting your head while rubbing your belly counterclockwise)
Anything that takes your mind away from the road when you're driving even if you can see the road is dangerous. (They found that talking to someone in a passenger seat is not as dangerous because if they notice danger and you don't, they'll inform you of the danger automatically by tensing up or whatever.)
If your brain worked like a single process cpu, it would be like setting Twitter to high priority while relegating driving your 2-ton SUV to low priority. It will work well enough most of the time, but sooner or later, you'll crash the SUV.
This will make driving safer for me. I'm already checking my speedometer and other instruments and often use a GPS. Now I can do all that while not removing focus from the road. This looks like a great device and the pre-order price is fantastic.
And yes, I have no problem with the head patting/belly rubbing. Have you ever seen a cop driving a patrol car? He's juggling radios, phones, a computer with a big screen for looking up warrants and stuff, entering plate numbers, looking out the windows for suspicious behavior - the actual road is a mere distraction. People can learn to manage their divided attention, and if they can't handle checking a speedometer without crashing into the guardrail they probably shouldn't be driving.
That said, I wouldn't use this to text while driving. Seeing who's calling and waving my hand to answer for a brief "I'll be there in 10 minutes" seems reasonable, however, and is safer than fumbling with the phone the old-fashioned way.
The thing with an activity as ubiquitous as driving is that when judging the usefulness or conversely danger of a certain aspect of it, you have to consider the least-skilled (or more susceptible to distractions) group of drivers. Saying "I can do activity X and driving together" is a nice anecdote, but it doesn't give much information as to the overall safety of activity X and driving.
For example, I would guess that there are people out there who can safely drive a car with their blood-alcohol level past the legal limit. There are presumably people who can multi-task (text or phone & drive) safely too.
Once these activities become acceptable, you can't pick and choose who is allowed to perform them based on some skill metric.
Deputy who killed former Napster COO after drifting into the bike lane while distracted by his laptop will not face charges because he was answering a work-related email
- Milton Olin Jr, 65, was fatally struck by a Los Angeles county sheriff's patrol car December 8, 2013, as he rode in the bike lane in Calabasas
- Deputy Anthony Wood was returning from a fire call when he took his eyes off the road to type a work-related message on an electronic device
- Olin was director of operations for Napster between 2000 and 2002 and was a prominent entertainment lawyer
- The victim's wife and sons have filed a wrongful death lawsuit claiming Wood was negligent
> while distracted by his laptop will not face charges because he was answering a work-related email
Somehow I feel that if I struck a cyclist while answering a work related email (not that I'd ever do such a thing) that I would not be getting off that lightly.
eh, in sf, you get a ticket for killing cyclists. Sometimes not even that. It's really not a big deal. So it isn't as if the cop got a special deal.
"We do not know of a single case of a cyclist fatality in which the driver
was prosecuted, except for D.U.I. or hit-and-run," Leah Shahum, the
executive director of the San Francisco Bicycle Coalition, told me. [1]
(Firefighter/medic, not cop) - we have an exemption from cell phone laws, but with the stipulation that it is to be used sparingly, and only in an emergency, i.e. it's recognized that it's not a good practice but sometimes needed (for example in my area, ambulances contact the hospital via cell phone, not radio, and depending on the severity of the patient in back, there may be a need for a driver to make contact - whilst ideally we either have additional manpower, or similar, it's not always possible). Personally, I think there abuses of this.
> Cell phones are not dangerous because the driver was looking at his phone or playing with the buttons when he had an accident. They are dangerous because they encourage your mind to wander.
I'm going to speculate that driving is such an activity that doesn't require constant attention and involves quite a bit of monotony. In such circumstances, mind wandering will happen—be there a mobile phone, Navdy, or nothing at all.
This is a human factor. The only complete solution to this issue seems to be self-driving cars, when your mind and its wandering are taken out of equation.
With that in mind, a mobile phone doesn't seem to stand equal to other causes of mind-wandering, contrary to your claim. A phone also obstructs large portions of the road from your view when you're using it.
> I'm going to speculate that driving is such an activity that doesn't require constant attention...
Stop there. What would lead you to this speculation?
Of course driving requires constant attention and care, the full time you are behind the wheel of an automobile. You're piloting a 2 ton machine made of whirling metal and filled with flammable liquid traveling at high speeds, usually within less than a meter of someone else doing the same.
There is never a good reason to divert attention from the task of driving while you are driving. Full stop.
> Stop there. What would lead you to this speculation?
First, I should've put “constant and full attention” there. My phrasing was off. As to why I came to this conclusion:
1. People often ride for a few hours without breaks. My assumption is that it's not possible to pay constant and full attention throughout this time—our minds are bound to wander.
2. The pattern I usually observe is when the driver, depending on road situation, varies the degree of attention they pay to the driving. At one time they're driving relaxedly and multitasking (talking to a passenger or someone on the phone—by definition they're not paying their full attention at this time), while at another they're more or less concentrated on the road.
Disclaimer—I don't myself drive a car, but I often observe people driving. I've observed both experienced drivers who drive frequently and more beginning drivers, the pattern described under (2) is the same.
Update: the comments here, coupled with my observations, make me believe—roughly—that a) drivers don't (can't) pay their full and constant attention to the road, and b) many are in denial of (a).
That reminds me of the pope, doesn't play the game but tells others how to play it.
Well, I do. I drive way too much in fact and I believe strongly that driving is a full-time 100% on the ball occupation. That probably saved my life twice this year alone and prevented one other probably bad accident from happening. I drive in places where traffic is very much unlike the traffic that you are probably used to (you'd call it a madhouse), dogs, other drivers, horse carts, madmen, trucks overtaking in blind corners, drunk people on the road (on bicycles, no lights). You name it they've got it here.
When I'm tired even a little bit I stop the car and sleep until I feel rested again. My phone is off. At night I use the GPS to tell me what's going to happen around the corner (hairpins in mountainous terrain where you can't stop are a real joy) when I can't find a place to stop safely to overnight. But as soon as I do the car gets stopped and I wait until it's light again.
I turn down the instrument panel lights to have good night vision as much as possible, this is plenty to read the instruments by if I have to and means I get to see what's on the road, which is a lot more important than whatever is on that screen. (Such as a very black and very large dog that jumped out of nowhere a few weeks ago).
This probably all may seem paranoid but it has served me very well over the years. Even so, I think that navdy has a spot, but only if you use it as a navigation device and place it outside of your direct field of vision. It screws up your night vision and that's bad enough when you have to look at it, it's much worse when that happens all the time.
The idea of 100% attention when thinking about the brain is just a simplistic notion to make discussions easier but inaccurate. Even in this simplistic approximation of the brain, the idea of 100% attention is pretty thin. If I'm driving somewhere I'm probably listening to the radio (deduct 5% attention points!) or thinking about wherever it is I am heading (deduct 5% attention points!) or if someone is actually in the car with me, I am probably interacting with them in some way (deduct 10% attention points!). And while I'm driving and keeping a constant vigil through the windshield for danger what if I see a glorious new Apple store that I didn't know existed?? That is going to hijack my brain for a bit (deduct 100% attention points!).
The radio , passengers and thoughts are much more passive and easy to tune out but even then I'm sure there have been plenty of accidents that are caused by daydreaming. A passenger can see out of the window and has awareness of the car's surroundings so they will usually know to shut up or at least not expect a quick answer to their question if you are doing a tricky manoeuvre. Electronic devices or people on the other end of a hands-free conversation both require interaction and do not have awareness of the situation that the driver is in.
I do drive myself. Have for 20+ years. Just drove 1300 miles over the summer vacation, sometimes on long monotonous roads, and I'd be lying if I was paying full attention all the time.
My experience is exactly as he describes. In city traffic, at traffic lights, or just before an exit, my full attention is required and constant (I actually dislike GPS because of this, it distracts, especially if notifications are late, I'm looking at you Google Nav - 'keep left at the fork').
However, after so many years of driving, I have also developed some sort of autopilot/'trance driving' mode. It is typically engaged on long legs, or when extremely tired on a very familiar route (e.g. going home). I betcha if you ask professional drivers like truckers, they'll tell you the same.
Edit: While in this mode, my 'look-ahead' window is maximized. I gaze much further ahead than I do in 'stress' situations. My focus point is definitely way past the windshield, usually several cars ahead of me. I gauge my speed by engine sound, distance to the cars ahead of me, local traffic flow etc etc. As such, I am not convinced that this heads-up display approach is a safety improvement. Sure, your eyes will be on the road, but by requiring a change of focus, you cannot look ahead to anticipate issues/changes/risks.
I have to agree. I do drive like this too over long distances. Anything else would just be too tiring. Maybe we expand the zone of perceived predictability. Fascinating stuff. Good point about having to focus in and out.
This plus Highway Hypnosis [1] show that some of us at least drive without full conscious attention.
You're going to get yourself or someone else killed one day. Remember that I can do everything in my power to be a responsible driver I am still subject to the sum total of the risks everybody else takes and driving when you're that tired is an un-acceptable risk.
Hate to be the type that pulls this one out, but when I became a parent I learned of levels of tiredness I never knew existed, and became aware of a whole segment of society (the parents) who go through most activities in their life at near crippling levels of tiredness. I agree it gets dangerous but it's not feasible to keep them off the road.
> Disclaimer—I don't myself drive a car, but I often observe people driving. I've observed both experienced drivers who drive frequently and more beginning drivers, the pattern described under (2) is the same.
When you're driving without distractions, sure, your mind wanders. You're thinking about a date tonight, or that jerk at work, or whatever. But as soon as your eyes pick up something of interest, like an exit sign, another driver, or a bad situation up ahead, you can immediately focus exclusively on the road. You can do this pretty quickly
Similarly, when you're carrying on a conversation with someone, the other person will generally quiet down as soon as the situation changes.
When you're on a cell phone, that changes. You're paying much, much more attention to a cell phone conversation than you are to someone sitting next to you because you have to listen harder. Not only that, the conversation is independent of the driving situation. Most people will not tell the guy on the phone with them to shut up; they'll just try to carry on the conversation. Even worse, a lot of people aren't paying enough attention to the road to realize that the situation requires more attention and that they need to put down the phone. This causes accidents.
Finally, texting is the worst - you're literally taking your eyes off the road to send a message.
Peak Hacker News/Silicon Valley: I have no idea how this system works, in fact, I've never used it. But I'm going to speculate on how it can be improved anyway.
I for one, completely agree with you. Now this is purely anecdotal, but then again everything in this debate seems to be.
I've only been driving for 7 years, but already had several benign accidents (no casualties or whatever, only some damaged metal). On each and every one of these situations, the cause was not speeding, nor my phone, nor any outside distraction, but just my mind wandering off the driving and thinking of something else.
Sometimes I get home and I do not remember the ride, not even which road I took or anything, and I think to myself, what could have happened while my mind was wandering. I just can't keep my full attention on something for that long, period.
For what it's worth, I remember reading two things:
1. Driving is one of those activities where people actually use a lot of their brains functions to do. This is partly why it can tire you out so much.
2. People speaking to a passenger drive as poorly as people otherwise impaired but the fact that they're both in the car (grounding them in the fact that they're in the vehicle) and that both of them pay some attention to the road helps mitigate the negative effects.
All I can recall is that I read #1 in a BBC News article and the latter on something I found on Google Scholar. I feel they're relevant. If you're interested, I hope it helps.
So maybe your should learn driving a car first. I agree that paying full attention while driving is definitely the hard thing to do, but it is also the right thing to do.
One of the problems is that whatever you happen to be focusing on, you also have to be able to react quickly to potential hazards. I'm pretty sure (guessing) that being not particularly focused on the road is still significantly better than being focused on a mobile phone/Navdy.
I've read the literature on multitasking while driving. Texting is one of the worst. Talking on the phone comes somewhere in the middle (hands free or not doesn't seem to matter), but even talking to passengers has a measurable decrease in safety. The problem is that people, as a whole, are willing to bear quite a bit of risk in order to indulge in their distractions, but their behavior additionally forces those around them to bear some of the risk as well.
I agree that self-driving cars are a huge way forward for safety, but in the meantime it makes sense to minimize human error.
> One of the problems is that whatever you happen to be focusing on, you also have to be able to react quickly to potential hazards.
True. From my anecdotal observation the reason why talking over mobile phone is dangerous (while talking to a passenger is not) seems to be social norms—immediately cutting off the conversation to focus on the road doesn't seem like an acceptable thing to do, and we avoid doing this unless absolutely necessary. For a more responsible driver, this ‘absolutely necessary’ threshold is pretty low—as it should be—but such people seem to be rare.
First, road accidents are are among top 10 causes of deaths in the world, so this isn't a small matter.
Second, there is research that shows that dividing your attention just between driving and talking can cause a significant reduction of reaction speed. Driving safely is not monotonous activity. Of course, if your car is crawling in a LA traffic jam, accidents are mostly non-fatal, but when you are driving 100km/h, cars are dangerous objects.
Driving safely on an empty freeway at 100km/h is one of the most monotonous things I can think of. Hell, if it's a straight flat section of road you are literally doing nothing except trying to stay alert in case something changes. The human brain (or at least mine) is not good at staying in a focused hyper-aware state for a long period of time while nothing's happening.
I believe that accidents caused by distracting devices are only a small % (really small) of this trend. The huge % of car accidents is because of alcohol abuse.
Your speculation is mostly right. Our brains are pretty good at automating repetitive tasks such as driving, so most drivers regularly don't pay complete attention.
The trouble is our brains primarily adapt to repeated stimuli eg driving in good conditions. Since no one spends most of their time driving narrowly avoiding accidents, that activity isn't one the brain can learn to automate ( well, maybe it's possible with a realistic driving simulator), so dangerous driving requires everyone's full attention.
Since we don't usually have advanced warning of when dangerous driving will happen, the best we can do is spend as much time as possible paying attention to road conditions.
this may get me down-voted, but i tend to drive faster and more aggressively than, uh say, my parent's would like me to [1]. when i'm driving this way, i'm fully engaged and almost always "in the zone." i constantly work towards a better position and continuously work to predict actions of all cars around me and the consequent reactions of other cars to that action, as well as any reactions i'd make at any point. my mental model of traffic is largely based on fluid dynamics, w/ hooke's law (springs) thrown in for stop/go traffic. i often joke w/ my wife that if there were an olympic event for navigating through traffic, i'd at least qualify for the team. while risks are greater than going 65 in a 65 and not changing lanes, i'm never ever reckless. some may disagree, but b/c of the heightened level of engagement, i do consider my self far safer than other cars on the road who commute home, thinking about work and largely disengaged. day dreaming? can't. texting, etc? cant. drinking coffee? can't. fwiw, i've always driven a car with a manual transmission, and i do feel it's a variable in lower levels of driver disengagement. i've never had an accident or ticket while driving in this manner.
driver disengagement is the problem, whether caused by a physical, visual, or cognitive distraction. the goal shouldn't be weighting how dangerous these various devices are, it should be on how to ensure drivers are engaged to a point where they can take over from auto-pilot (repetitive aspect) when something goes wrong.
[1] i'm not a kid, i have many kids of my own, just trying to avoid quantification of driving.
Associating this product with blood money is highly offensive and it's disappointing that this is the top comment. The team behind this has put a lot of sweat and tears into making this a reality, as is always the case when starting a business of any complexity, and especially true in tech when operating in uncharted waters.
The important tech is heads up display projected rendering on glass in a car. As long as that works well there will be good applications beyond reading twitter. safety information, car and dashboard alerts, and gps map information all come to mind. Anyone who has ever played a video game should be familiar with HUDs that help you and aren't distracting.
Just because the founders put effort into something doesn't make it ethically good. The advertised use is still messaging and communication, and I'm sure if they open it up to developers there will only be more distractions like flappy birds on a car. The point is a powerful technology with smart people and good intentions behind it can always result in poor unintended consequences. In this case I can see a lot more potential consequences than advantages.
The team behind this has put a lot of sweat and tears into making this a reality, as is always the case when starting a business of any complexity, and especially true in tech when operating in uncharted waters.
As long as we're being figurative, a lot of sweat and tears have gone into missile design and prison labor contracts. And this is not completely uncharted waters, phone-HUD has been a thing for years now.
As analogies between analogies go, this is like comparing the comparison of Charlie Chaplin's mustache to Hitler's mustache to the comparison of Charlie Chaplin and Hitler.
I guess virtually everyone who has ever played a video game will remember a moment where you got killed because you looked at your ammo reading for a split-second.
"Cell phones are not dangerous because the driver was looking at his phone or playing with the buttons when he had an accident. They are dangerous because they encourage your mind to wander."
So you are claiming that having to look away from the road for possibly whole seconds to deal with a phone is not really dangerous, but what is dangerous is your mind wandering? I'm sorry but experience and common sense says otherwise.
I would also argue that your second point is not as not clear cut either. Having some sort of distraction is definitely helpful most of the time when driving long distances. I personally find audio books very greatly help to fight off monotony, which in turn keeps my attention higher than if I was not being distracted.
> So you are claiming that having to look away from the road for possibly whole seconds to deal with a phone is not really dangerous, but what is dangerous is your mind wandering?
I'm not OP, but it's not that your mind is wandering per se (which suggests a neutral state) but your mind is actively focused on something other than the road, like an HUD in front of your face.
Peeking at the next turn on nav mode is not a big deal, but if you're composing a text using voice, I'll bet anyone $100 that the voice recognition isn't good enough that you won't be staring at the screen to check it's getting the right words.
The thing I dislike most about this product is that it deludes people into thinking this is a "safe" way to operate your phone and text while driving, and basically gives permission to do so. No way to text while driving is safe, not really even at red lights.
Hmm. I think I took Yxven's comment out of context which in turn made my comment out of context. I agree that interruptions like reading a text message are dangerous regardless of how they are done. They are obviously more dangerous if you have to take your eyes off the road to do it is what I was saying.
In regards to long trips, I still maintain that having a distraction like music, audio books, or company to talk to is actually safer than not having them. Your brain getting tired of monotonous activity and scenery is a real thing as anyone who's done a 10 hour drive can tell you. But again my comment wasn't really in the same context as the parent I guess, so there's that.
> In regards to long trips, I still maintain that having a distraction like music, audio books, or company to talk to is actually safer than not having them. Your brain getting tired of monotonous activity and scenery is a real thing as anyone who's done a 10 hour drive can tell you.
This is of course true, and I noticed that drivers anticipating longer trips often like to take someone with them so that the passenger can keep them awake and concentrated.
But then again, on a long trip you really should make those 30-minute stops every 3 hours or so.
> They are obviously more dangerous if you have to take your eyes of the road to do it is what I was saying.
Yeah, for sure. That's the problem with this sort of product: you release it without texting functionality and [most people will reach for their phone to text] and [some people will stop texting while driving]. And lose product sexiness etc.
You release it with texting and people will think it gives them carte blanche to text while driving. Both not great outcomes.
Not that it's without dangers, but you don't have to look at a screen to verify text message dictation. You dictate, it reads it back.
I think better would be a standard library, like "report I'll be late," that relays my current coordinates and ETA in the message to my spouse. (And simply showing up late would make me nervous; reporting my delay relieves tension.) I'm not a brain scientist so I can't say what the total effect would be.
> I'll bet anyone $100 that the voice recognition isn't good enough that you won't be staring at the screen to check it's getting the right words.
Let me take that bet ;). Some people really don't care, and it makes me want to kill them when I get a voice-typed message that's complete gibberish because the sender thinks comprehensibility is for the losers.
So you are claiming that having to look away from the road for possibly whole seconds to deal with a phone is not really dangerous, but what is dangerous is your mind wandering?
This is a false choice and something that the person you are replying to never said.
> So you are claiming that having to look away from the road for possibly whole seconds to deal with a phone is not really dangerous, but what is dangerous is your mind wandering?
The point is that anything that distracts your mind/vision from the road is dangerous, be it looking at your phone or reading a tweet in a transparent HUD display. What Navdy is building, while interesting, isn't necessarily safer.
I agree with what you are saying and you shouldn't be reading messages or w/e when driving, but surely looking away from the road is more dangerous than not? In the very least it takes more time. Again I'm not encouraging the behavior, just saying not all distraction are equivalent...
No, this is only partly true. Driving is primarily a visual activity. If your eyes are not on the road, then your chances of an accident increase. If you are looking down at your mobile, then the chances of an accident increase markedly.
Yes, looking at a HUD increases your risk of an accident. The best option is to have 100% attention focused on the road and your surroundings. If I had to choose between mobile or HUD, HUD would win every single time. If I had to choose between HUD and nothing distracting, then obviously the later is better. Yeah, just put the freaking phone away when you are driving.
It is more dangerous to not look at the road than to look at it. Surely.
This is safer than looking at a phone. I agree that it has the same inherent problem of distracting the driver with other tasks and making it easier for your mind to wander. But it's still a step up.
Perhaps they should make it a "driving tasks only" device. Speed, navigation etc. But unfortunately the law allow devices in the car that provide other information and services as long as they're hands free and they're not playing video. While the law allows it, people will fill that gap and these guys would fail miserably by ignoring that side of the market.
Edit: I read comments further down that enlightened me to the point of view that this creates the illusion of safely texting while driving, and people may be texting and tweeting more while driving, distracting them more rather than less. The laws need to change.
This is pretty accurate, but I think one of the issues with driving is that it's often really... boring.
I mean, I know that it's incredibly dangerous, but because I do it for hours every day, I become desensitized to the danger. So, I check out my facebook feed or respond to that text message. Before smart phones, I would pick up a paper book that I had just bought and skim a little 'cause I just couldn't wait to get home. If it weren't that, I might be looking for wildlife out my passenger-side window or fiddling with the radio, etc.
I guess I'm a bad person, but I'm pretty confident that I'm not the only one. My guess is that a device like this that can keep your attention without diverting your eyes from the road is, in general, going to improve safety.
How about the speedometer dial, the fuel and the oil temp gauges?
Those need to be checked regularly as well and they occupy mindshare. You even need to focus on them and given that they are a lot closer than the road that takes time away from the road, refocus, then inspect the dials then look back out of the front windshield and re-focus.
Driving itself is a multi-tasking effort.
The number of buttons and indicators in a car (especially a high end one) can be quite distracting.
And not checking your speed diligently where I live gets expensive really quickly, 3 km over the actual limit (as checked by the GPS) will get you a ticket. So I actually drive with the GPS 'on' even when I know perfectly well where I'm going because it checks my speed without me looking at it.
I think the speedo dial is a dangerous distraction when speed cameras are about. I know I focus almost entirely on the speedo and only use peripheral vision for the road ahead when going past a speed camera.
When there's no speed camera or other risk of speed trap, I don't pay attention to numeric speed at all. Instead, I drive to the conditions, and approximately follow the speed limit as appropriate - but I may be 5 or 10 over or under depending on how clear the road ahead is of hazards.
Fuel, oil and other gauges don't change constantly and don't demand attention with flashing and animations, unless something is seriously wrong - in which case the vehicle should be stopped.
I should add, though, I don't actually drive. I ride a motorcycle and scooter, daily, all year round in London. Anything less than 100% focus is a quick route to A&E.
In NL they claim the speed cameras are for safety. I'd believe that if they put them in places where people go faster than the 'safe speed', but instead they put them in places where there is a ton of traffic. I suspect that there is an economical motive at work here rather than a safety motive but I can't prove that.
All I do know is that I spend too much time checking that damn dial. So I fixed that by setting the GPS to warn me with an audible alarm when I get to 1 km over the GPS measured speed compared to the posted limit of the road I'm on (it adjusts those automatically). Very useful.
Looking at something indeed doesn't mean paying attention to it. That's why head-up displays can be dangerous (just like handsfree phone usage).
Daniel Simons, a professor in the Department of Psychology at the University of Illinois, says this in his episode of the You Are Not So Smart podcast:
I agree with you in that navdy will not eliminate risk of attention loss. But at least it should reduce the attention loss. Sure, any kind of attention loss is not acceptable in theory. But if navdy is found to reduce attention only as much as say talking to a co-passenger, then may be it's not a bad trade-off. Like one of the other commenters said, we cannot ensure that drivers have 100% attention. Anything that at least reduces risk is still a good thing.
Did it on the first attempt, switched hands and legs without difficulty either. And I usually suck doing anything with my non-dominant limbs. Must be all the piracetam.
Ah yes. Do you also give philosophical advice by any chance?
Displays like this are standard on a lot of high end performance vehicles. The teams who worked on stuff like this can run circles around your BS in psychology.
I drove cars with this technology and it's actually better since you don't have to look down at the wheel or at the awkwardly mounted portable GPS/phone that usually falls off the mount every other day.
Cell phones are not dangerous because the driver was looking at his phone or playing with the buttons when he had an accident. They are dangerous because they encourage your mind to wander. Most people's brains are really not good at multitasking. (Try patting your head while rubbing your belly counterclockwise)
Anything that takes your mind away from the road when you're driving even if you can see the road is dangerous. (They found that talking to someone in a passenger seat is not as dangerous because if they notice danger and you don't, they'll inform you of the danger automatically by tensing up or whatever.)
If your brain worked like a single process cpu, it would be like setting Twitter to high priority while relegating driving your 2-ton SUV to low priority. It will work well enough most of the time, but sooner or later, you'll crash the SUV.
(Source: BS in psychology)