Multi-Tasking And Humans?

I reckon the short answer is we humans cannot do this. Let’s have a look at it.

Firstly I’d like to compare our human brain with the computer Central Processing Unit or CPU.


The CPU executes a piece of code written in a particular language style which can be converted into machine code that the computer can understand, and perform the required actions.

Now think about this language. You can only write ONE instruction per line and the machine can read this one line, take the action and THEN move on to the next instruction. It is a linear process.

So no multi-tasking here. One line of code at a time. Per CPU. More about that later.

Lightning Speed

But wait, there's more. Computers do this at lightning speed. The speed of electricity running through wires and bits of esoteric electronica which is 176,000 mph. Or 283,244.544kmh. Fast? Yeah.

Time Slices

Computer engineers decided to use this speed and divide the capability of the CPU into time slices. Thereby allowing multiple users or multiple tasks to run at the same time (seemingly). These slices were fixed and the CPU automatically swapped to another queued task or a waiting user, when the allowed time had elapsed.

This was way cool,

Time Sharing

But some processes took less time than the slice allowed and some more. Some users similarly were not so regimented. Some users with urgent tasks didn’t like the delays this caused.

Enter the time sharing system. Here the program code included flags to note that a particular part of the program being executed could be interpreted to allow the system to share itself with another user or another series of instructions.

Of course, this is not entirely true and not as simple as I have outlined, but for our purposes, it is good enough.

Parallelism / Context Switching

Because of the speed of execution, this computer appeared to be doing more than one thing at a time. Ie multi-tasking. Or parallelism. But there is a downside to this. We call it ‘context switching’. The act of reassigning a CPU from one task to another one is called a “context switch”; the illusion of parallelism is achieved when context switches occur frequently or fast enough.

As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors. Obviously, if you have more than one CPU, each can handle one part of a task (the code can be split into 4 or more series of instructions which are then joined at the end to come up with the desired result (an over simplification – but you get the idea.)

Enough of computers.


How does this relate to our human brains?

For a start we have two hemispheres in our brain. Left and right. tells us: The left side of the brain is responsible for controlling the right side of the body. It also performs tasks that have to do with logic, such as in science and mathematics. On the other hand, the right hemisphere coordinates the left side of the body, and performs tasks that have do with creativity and the arts.

These tasks are essentially opposite, or at least completely separate from each-other, therefore it is a stretch to imagine that they happen in parallel or simultaneously. Isn’t it?

No multi-tasking then?

Parallelism / Context Switching

What this means for us humans is our brains indulge in the same behaviour as computers. “Context switching”. Creative v’s logical. Back and forward as the mood takes us.

Dean Yeong

Dean tells us:

Human multi-tasking is an apparent human ability to perform more than one task, or activity, at the same time. An example of multi-tasking is taking a phone call while driving a car. Multi-tasking can result in time wasted due to human context switching and apparently causing more errors due to insufficient attention.

The short answer to whether people can really multi-task is NO. Multitasking is a myth. The human brain cannot perform two tasks that require high-level brain function at once. Low-level functions like breathing and pumping blood aren't considered as multitasking.

When the brain tries to do two things at once, new research shows it divides and conquers, dedicating one-half of our gray matter (we have 2 frontal lobes) to each task. But forget about adding another mentally taxing task: The work also reveals that the brain can't effectively handle more than two complex, related activities at once.

While most people think multi-tasking means getting more done in a shorter period of time, the truth is exactly the opposite. As mentioned above, multi-tasking simply means switching back and forth between two or more tasks on hand (in our head); it’s not a parallel process and execution.

In my quick down and dirty research for these notes I found one chap who postulates that our brains have up to 50 core processors, so theoretically, just as in computers, we SHOULD be able to competently multi-task.

However, I didn’t find any data that gave any credence to this idea. Maybe true. I just didn’t see it.

Two Tasks

Let’s have a look at a tale of two tasks

  • Cooking a family meal in a slow cooker, and
  • deciding whether or not to go on a first date with an acquaintance from the gym.

The Meal

Cooking a meal. You don’t really need the recipe, you can access memories from past instances via the left side of the brain. But this time you decide to change the spice mix a little and swap in some veggies the kids like and swap out some they don’t. Right brain.

And you need to remember that the squash and other soft things need to be added later, while those like potatoes and broccoli go in first. This part also requiring input from the creative right hand side of the brain. So you are already adding complexity to your situation. Context switching between the two hemispheres.

The Date

Now the other week you exchanged phone numbers with another gym rat, and this person has rung and requested that you go with them to dinner and a movie sometime this week. You said you’d get back to them.

The thought processes here revolved around: did you want to go out with THIS person, did you want to go out with anyone? What did this outing entail? Baby sitting for one. Quite a bit of thinking here involving memories again and some creative work.

Two tasks

So here we have 2 tasks each with two types of thinking required.

Moving forward to the end of the week. The food, while being nice and all seemed to be missing something. A tad of salt in the bowl sorted it. How did you forget the salt?

The date was a train wreck. It fell apart when the other person said reasonably early on, “Well enough about me – What do you think of me?” Narcissism gone wild. You asked yourself, “How did I miss these signs when we were setting this up. This is not my first rodeo. Should have seen it coming.”

Context Switching

The real reason is that in making an effort to think of more than one thing at a time you managed to miss a few vital bits of information during the context switching phases.

Perhaps this is multi-tasking on one level, but information slippage on the other.

Can we really call this multi-tasking? Yes or no?

What do you think?

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