Thinking has its limits

Have a look at Box 1.1.

Although I asked you to add 2 + 4, you didn't. You just said ‘6' because it is over-learned, and the answer is pre-stored in our heads. 2 + 4 triggers the answer 6. This is an example of simple stimulus-response learning - you don't know where the answer came from, it just appeared in your consciousness triggered by the stimulus ‘2 + 4'. You know the answer came from your memory, but you were not aware of the process by which you accessed it. ‘It is the result of thinking, not the

BOX 1.1 SIMPLE PROBLEMS

Here are a number of simple problems. Co through each one and try to solve them, while at the same time trying to assess where the information you are using is coming from.

Add 2 + 4

Add 28 + 43

Multiply 43 x 28

Multiply 433 x 288 process of thinking, that appears spontaneously in consciousness’ (Miller, 1962, p. 56).

When asked to add 28 and 43, you were probably aware of something going on consciously in your mind. There are various ways in which you could come to an answer but in each of them you would trigger partial answers without obvious calculation (e.g., 2 + 4 and 8 + 3), and then you would have to store those answers temporarily before combining them. You have 2 + 4 in the ‘tens column" if you like, giving 6 tens (60) and 8 + 3 gives 11 which you then add to 60 to give 71. Here, you are using the unconsciously accessed information that popped into your head and then consciously manipulating that information. But then again, some of you might have come up with 71 without much conscious thought at all.

The third sum is likely to be more taxing and involves processing the figures and storing several temporary answers or sub-goals. For example, one sub-goal might be to find the result of 3 x 8. Another might be to decide the best way to tackle the problem in the first place. There are strategies you might choose from such as attempting long multiplication in your head while trying to keep the results of the sub-goals in mind at the same time. You might try 40 x 28 first, then 3 x 28 and add them, and so on. If it’s not the kind of activity you are used to, you may even find that your mind seems to run out of space to complete the calculation.

As for the fourth sum, if you were trying to do it in your head using the method of long multiplication you learned at school you would be struggling.

The point of that little exercise is that:

• over-learned items or behaviours can come to mind automatically:
• some activities require conscious manipulation of information;
• we need to be able to store information temporarily;
• finally, and perhaps most importantly, our thinking takes place in a kind of workspace known as working memory (WM) and WM has a limited capacity - there’s only so much information it can manipulate at any one time, so this kind of thinking is effortful and slow.

Our thinking can also be affected by failing to access the memory we are looking for even though we know we have it (the so-called tip-of-the-tongue phenomenon). Or we may access information that is not actually helpful to solve our current problem. When we are sitting an exam, we may remember that the bit of information we need is at the bottom of the left-hand page of the textbook, but we can't remember what it actually says. We had no intention of remembering which part of the page it was on yet that’s what has stuck. Context can have a big influence on what we can recall (Godden & Baddeley, 1975).

Undirected thinking

Unlike other forms of thinking, daydreaming is not directed towards a goal (although one can daydream intentionally). We all do it. Allowing our mind to wander is easier than concentrating. While it is possible to talk aloud while solving a problem - essentially describing the current active contents of WM - you can't do that with daydreams. You can express what you have just thought about but not what you are currently thinking as that would disrupt your daydream. When you ask someone ‘what are you thinking about?’ you are asking them to tell you about the topic they are thinking about, not usually about what goal-directed sequence of mental operations they are currently consciously aware of.

When people are given demanding tasks to do, certain areas of the brain ‘light up’, particularly in the frontal lobe. At the same time, there appears to be another network of regions in the cortex whose activity reduces when we concentrate on a task. When it is over, and there is nothing further requiring attention, this ‘default’ network comes back online, hence its name: the default mode network (DMN; Raichle & Snyder, 2007). It seems to be able to jump between one mental state to another without much effort and to link to personal episodic memories in particular, allowing us to think about the past and use it to predict the future in the form of daydreams. However, when we concentrate on something, we are using an executive control network that is not so richly connected. To get anything demanding done, the executive control network has to make an effort to submerge the default network. There are therefore these two contrasting types of thinking that appear to be mediated by different brain regions: focussed thinking directed towards a task, and undirected, the kind that takes over when we are trying to get some work done and we find ourselves staring out the window daydreaming instead.