I heard a story once about Albert Einstein, who, after a hard day’s work revolutionizing physics, left the university and went on his way, but ended up lost and confused, unsure where to go. It was like his brain had been working so hard that he couldn’t find his own house anymore; the supreme difficulty of whatever thought process Einstein was engaged in at work meant he had almost nothing left in his gas tank for the performance of even the most simple mental tasks, like recalling a piece of information he used every day. There’s no evidence that this story is true, and it’s about as extreme an example as you can get, but the phenomenon of cognitive load is clearly real and relevant to those of us who are interested in education.

Cognitive load is like the mental energy we use to perform difficult tasks. This can take the form of  solving  a mathematical problem, forcing ourselves to do routine household chores when we’d really rather watch TV, or biting our tongue when somebody annoying is provoking us. Apparently, all of these tasks take the same kind of mental energy. It’s effectively the same thing as stress; all of these situations act like a work-out for our brains. Just like you need a rest between physical resistance exercises if you want to avoid damaging your muscles through over-training, your brain can only take so much mental stress before its performance drops and the effect on your development becomes negative.

There are a number of strange phenomena which seem to be related to this concept. Apparently, if people are put in a difficult situation and have been making stressful ethical decisions, for instance making sacrifices for the benefit of others, they are less likely in the immediate future to resist their impulses. It appears that putting yourself second for a long time makes it harder for you to do the apparently ethical “right thing” next time. This works the same if you were doing some other kind of mentally difficult thing, like trying not to eat a tempting sugary treat, working on a complex intellectual exercise, or waiting for something. In any of these situations, people were less likely to exhibit restraint if they were tested immediately afterwards.

So it looks like our brain only really has one gas-tank, and it fuels pretty much any difficult thing we do. This relates to how much effort it makes sense to put in each day. It seems like today’s society glorifies the state of being busy, the rushing from one engagement to the next. Our lives are over-scheduled and we’re expected to be productive much of the time. It looks like our genetic heritage might not be entirely suited to this. Our brain can probably only manage about four hours of useful work a day, for most of us, and the rest of what we do is largely on autopilot. It’s important not to over-exert ourselves mentally, and to save our energy for the important stuff so we don’t get drained working on all those other things that take up our time and cognitive capacity. A healthy balance is required, such that we experience sufficient stress to promote growth, and we exert effort in areas which will reinforce our learning and help us continue to develop, but without imposing expectations on ourselves which could end up being counter-productive.