ExposureBlog

Human Error researcher James Reason claimed that human beings can consciously process, at most, about five different things at one time.  Unconsciously, they rely on learned behavior.  One example: driving down the road on a clear day with few distractions.  That’s learned.  Then the cell phone rings.  That’s new, and that’s ONE new item.  Suppose the driver has programmed the phone to produce a special ring that is associated with a certain caller.  If that particular ring sounds, then the driver knows it’s that caller.  That’s when the conscious links to that caller come into play.  That’s the second thing added to the agenda that the consciousness has to deal with.  If the links are extensive and associated with problems (i.e. the driver’s accountant, parole officer, etc) then the space in the “consciousness clipboard” begins to fill up rapidly. 

Now, suppose this happens to be a new cell phone (the driver lost the other one because a clip failed and also because he had gained weight forcing the cell phone FROM his belt and onto the floor.  Or ground.  Somewhere.  Bottom line, he isn’t sure how to use it.  Worse, the phone is a little Sanyo model with the camera button on the right edge–so when he knows that when retrieves it from his belt he runs the risk of hitting the button, taking a picture of the floorboard of his car—and losing the connection.

Conscious things to consider: Three. 

Now, he’s driving down the road at 88 miles per second, one hand on the steering wheel, one holding the phone.  Before he’s even started the conversation 60% of his available conscious attention has already been used up.

Then, he begins the conversation–one that will likely take up at LEAST another 20%–and probably more.  In fact, if the caller presents the driver with only two problems to solve, that’s probably more than he will be able to deal with properly.

In heavy rush hour traffic plugging along at 20 miles per hour (Goodyear Blimp speed) it probably won’t cause much of a problem–beyond a fender-bender.  At sixty miles an hour, funny things can happen. 

For one thing, that unnamed entity of the subconscious driving the car might think the driver is running late and want to solve the problem by speeding up a bit.  Or a lot. 

I haven’t done a survey (scientific or not) to determine this, but where I live it seems the ones driving the fastest, are the ones using cell phones.  I once saw a guy blast through a Starbucks parking lot at around 30 mph–narrowly missing cars and people–and he was talking on a cell phone.

If you object to the “5 things” limit (”surely I can multitask better than that!”) drive on over to the nearest four-way stop that involves dual lanes of traffic.  That is, intersecting streets EACH with four lanes of traffic (two in each direction.) Here, the driver is presented with eight things to evaluate. See how easy it is to keep track of everything?  Notice if any of the drivers jumped their place in line?

I think Reason’s work explains a lot about safety and about how accidents happen.  The conscious clipboard just fills up.  Forget Root Cause Analysis, just count the threads being processed. 

More on this later.

Since many cases are won or lost on the testimony of eyewitnesses, a recent study cited here should raise some eyebrows.  It concerns the psychological phenomenon known as inattentional blindness, or the inability of some normal individuals  to recognize something when their attention is directed elsewhere.  The phenomenon is well-known in psychology. Visual expert Marc Green has a good article on inattentional blindness and human error,  and there is a book on the subject by Australian researchers Arien Mack and Irvin Rock.

I have read depositions in which the deponent is asked over and over whether he or she saw something take place.  If the response is in the negative the assumption is that the event did not, in fact, occur—or that those who say that it did are not telling the truth.  Well, not so fast.

In the study, conducted by Dr. Seema L. Clifasefi of the University of Washington at Seattle, 47 participants were asked to watch a basketball game and count the number of times a basketball was passed back and forth between teams.  Some were given an alcoholic beverage and others were given an alcohol-free beverage.  During the game, a woman in a gorilla suit appeared on the screen, stood amidst the players, beat her chest and walked away.  When questioned later whether they had seen the gorilla, fully a third of the participants had NOT noticed the gorilla.  Of those not consuming alcohol, only 46% recalled seeing the gorilla.  Of those consuming alcohol, only 18% recalled the gorilla.

It would seem, then that if an eyewitness was engaged in behavior that required his full attention, the odds of noticing details of a specific incident may be less than 50 percent. 

In the summer sun, the inside temperature of an automobile with the doors closed can rise 19 degrees in ten minutes and 43 degrees in an hour.  Anytime you prepare to lock and leave an automobile, take a few seconds to “sweep” the car or van visually to make sure you haven’t forgotten something–or someone like a baby, toddler or pet.  Left inside a closed automobile, a child’s core temperature can reach the lethal 107 degrees F.

Results of a just-published study (read about it here, here and here) reminds us again that driving while drowsy is hazardous.  Also not recommended is driving while intoxicated, driving while talking on the cell phone, and driving while putting on makeup.  Or any combination of the above.  I’ve had a few safety cases involving long haul truckers and I always suggest taking a look at the driving logs, then applying MapQuest and Excel to see how fast they would have had to drive to comply with their records. 

While there is a substantial amount of research on the driving while drowsy (here, here and here) there are surprisingly few books on the subject.  The classic for the general audience is probably Stanley Coren’s Sleep Thieves.  Recommended.