Probabilities and awareness
You're standing in line at a popular taqueria. It's busy, and a bunch of people are waiting to order both ahead of you and behind you in this line. Down at the other end off to your left, one of the employees toils with a dish rag, dish tub, and a metal cart with wheels.
The kitchen is off to your right. Due to poor restaurant design, the employee will eventually need to cross through the line of customers after clearing those tables. Meanwhile, those customers are waiting there, craning their necks up at the menu in an attempt to figure out what they are going to get. There are tastes to weigh, prices to consider, and calorie counts versus diet budgets.
In their heads, the wheels are spinning with calculations. All the while, the queue slowly inches forward as orders are taken and customers move away to either grab a table or wait for their takeout bag.
Other wheels are spinning, too. The employee has finished his rounds and is now approaching with that metal cart. He and the cart are going to need about six feet of room to maneuver through the line without hitting anyone or anything.
You have a small amount of control over the line, in that you can choose to move up at your own pace, and can subtly negotiate for more or less "personal space" as needed. Perhaps you can time things just right so that a gap exists exactly when that cart arrives so that he can pass on through without having to stop, get the attention of people, jostle them around, and then hopefully pass through without incident.
So the question is: did you even notice this guy in the restaurant at all? Did you realize that there would eventually be a need for him to pass through? Did you figure out when you'd be in the zone when you might be able to control whether a gap exists or not? If you were standing there with others, did you manage to clue them in as to what you were doing?
I know, it can be hard to do this sort of thing. Still, some people manage to pull it off most of the time, while others never seem to "get" it at all. Everyone else is somewhere in between.
This is what I think about when I think of "situational awareness" and, yes, let's face it, multitasking. Does the act of ordering consume all of your cycles to the point where you completely lose all other data from the world around you?
I get that people are wired differently. Really, I do.
I just have one request for all of those strongly focused software people out there who block out the world for whatever reason: can you stop walking down the middle of lanes in your company's parking lots while completely oblivious? You'd think a few thousand pounds of self-propelled steel and plastic that's humming and clicking just a few feet away would get some attention, but apparently I am wrong.
My restaurant example can translate straight across to driving. Instead of "restaurant", think "highway 101". Instead of "line", think "lane", instead of "small gap", think "Mathilda onramp", and instead of "bus boy with a cart", think "underpowered, overweight truck".
You either see it coming and get out of the way, or you quickly become part of the problem.