RAM holds the current information that a program is working with, but it doesn’t hold on to it forever. Once the program has exited, the RAM it was using is (ideally) reclaimed by the operating system for use by other programs. If a program needs to keep information for the next time it executes, it will get written to the hard drive or to another form of persistence.

I imagine short-term memory as being very similar to RAM. The thoughts are in your head, but they aren’t going to stay there forever. Even long-term memory is not entirely reliable; the act of recalling something changes it slightly. So if our memory isn’t the best place to keep ideas for later, where should we keep them? In writing.

The act of reading words doesn’t change them. The letters which were printed may become illegible but they will never change. The information that those written words encode persists, and is the same every time you read it. The written word is how we have aggregated the collective information of our entire species with the accuracy and efficiency that we needed to make our social and technological advances.

One of my goals for 2010 is to write more things down and stop trying to keep so much in my head.

I’ll close this brief thought by quoting a blog post I read recently about writing:

The amount of information our brains can fit into our short term memory at once isn’t a lot. If you never have thoughts that require notes, then all your thoughts are small or unoriginal enough to fit into your tiny short term memory.

Writing allows you to record your short term memory into a format that you can examine and reflect upon, so you can suss out what makes sense, and how it makes sense, and then expand on the original seed. When you expand your thought all the way into a piece of coherent writing, it becomes complete. It would have been impossible for you to have that size of a thought without writing–your brain just isn’t powerful enough.

One of these parallels between humans and computers is the way that we multitask. Computers only seem to multitask by switching between tasks rapidly, with the exception of new multi-core and multi-processor systems, which can run as many tasks in parallel as there are cores or processors. So it was interesting to read recently that the prevailing theory is that humans multitask in precisely the same way!

Analogous to a multitasking CPU, current experimental psychology research shows that interference occurs when we attempt to perform even simple tasks simultaneously. There are certain exceptions to this, particularly when one of the two tasks is stored in “muscle memory”, but this is because we can perform such tasks without even thinking about them. In many other cases, the effectiveness with which we perform the tasks is diminished when we are doing more than one task at the same time.

It is also common wisdom in IT that when somebody is deep in his/her work (commonly referred to as flow), an interruption of even a few seconds can result in 15 minutes of lost productivity. While I’ve never verified the actual number, I have often had trouble putting myself back on a task after being jolted out of it by a short interruption.

When a CPU switches tasks, it must perform a context switch. The current state of the program that is running on the computer, including the values stored in the registers, a reference to the next instruction to execute, and other housekeeping information are stored in memory (RAM). When the program comes back, the stored information is put back into its proper places so that the CPU can pick up where it left off. This is a fairly costly operation as the CPU cannot access RAM even a fraction as fast as it can access its registers. Of course, this means that when a CPU runs two programs simultaneously, it is less efficient at each than if it were concentrating entirely on one program or the other. Determining when to switch to a different program is therefore an incredibly important concern in the design of modern operating systems.

I’ve witnessed human “context switching” in a co-worker of mine. When I knock on her door to ask her a quick question about work that I’m doing for her, she asks me to give her a moment and looks to be deep in thought. She then asks me to repeat my question and answers it with surprising conciseness and accuracy. She has told me that she needs to switch from the mindset of what she’s currently working on to the mindset of what I’m asking her or she can’t answer properly.

This isn’t to say that multitasking is bad, but I am acutely aware that when I do multitask, I am not going to be able to perform each task as effectively as if I were focused entirely on one. Also, there are certain points at which it is easier or more natural to switch from doing one thing to doing another, particularly where I’ve accomplished a sub-goal in the task or where I’ve written down detailed notes on the current state of what I’m doing, which makes it easier to switch back to it later.

What do you think?