How to diagnose dysrationality

After all, many of the biggest losers were professionals well known for their cerebral powers (Nicola Horlick included). Now there is a term for this seemingly illogical behaviour: dysrationality. We all know doctors who smoke and CEOs who behave like 12-year-olds. For years, scientists have been trying to figure out how people can be both brilliant and train wrecks at the same time.

History, after all, is full of examples of intelligent people doing dumb things. Last week we saw Alan Duncan MP, a man charged with reforming MPs' expenses, duped into saying MPs were forced to live on "rations" and "treated like shit" by eco-activist Heydon Prowse, who caught the incident on a hidden camera.

So isn't intelligence an umbrella term that means you can figure anything out? Absolutely not, says Professor Keith Stanovich of Toronto University, who studies intelligence and rationality. What he has discovered (and published in his book, What Intelligence Tests Miss: The Psychology of Rational Thought) is that people who score high in IQ tests can score really badly on tests which assess rationality.

"So-called fluid intelligence' is the ability to sustain imaginary worlds while under cognitive load, and crystallised intelligence' is a measure of general knowledge and acquired vocabulary," he says. "Neither assesses rational thought, which concerns managing goals, efficient goal attainment, and attunement of beliefs to the world."

So someone able to conduct a long and difficult debate on global warming or Wittgenstein may join a cult or invest in a crackpot scheme that a less intelligent mortal might have seen right through. Also termed a "thinking disorder", dysrationality explains those people who hold important jobs but talk total rubbish at dinner parties.

This, Stanovich explains, is because the mind has three parts: the autonomous (spontaneous, no conscious control), the algorithmic (logical thinking that IQ tests test) and reflective. The latter is the part that decides whether you consider the Madoff investment idea suggested by your best friend by wading through the technical literature or whether you skip the hard work and go with the autonomous mind that says, "She invested and look how rich she is!"

Jerome Kerviel, the French trader, clearly was only using his autonomous brain when he brought Société Générale to its knees by losing 4.9 billion. The reflective mind is the one most likely to get you into trouble, regardless of whether or not you have Einstein's IQ. This is because most of us can't be fagged to actually think through silly, boring problems that require some level of reasoning.

The evolutionary explanation is that when we were being attacked by sabre- toothed tigers we didn't have time to consider the myriad options using our advanced algorithmic mind. We learned to limit brainpower when decisions had to be made quickly. According to Stanovich, most people don't want to use their full mental faculties unless, say, they are solving the current economic crisis or attempting to cure cancer. We are all "cognitive misers" who prefer to avoid "overthinking".

When it comes to day-to-day thinking most of us try to spin things in our favour (this is called "my side" bias) to keep life easy. So when someone tells us that they lost 10lb on a bacon-only diet we do it too, despite the constant health warnings in the newspapers.

All these behaviours fall neatly under what Stanovich calls "mindware". When we have contaminated mindware, we fall for the person everyone else knows is a gold-digger or join the same sect as Tom Cruise or Madonna.

Most of us can count stupid/smart people on both hands but the good news is that the really smart can be made more rational — if they can be bothered. Real IQ is fixed by the time we become adults but rational thinking always has room for improvement. Unfortunately, it requires having to update the faulty mindware and do some boring reflective thinking.

Five ways to get more rational

1. Consider the possibility that you could be wrong.
2. Take the opposite point of view on subjects you feel strongly about.
3. Avoid "my side biases" by using your algorithmic brain to read the research and think beyond what your best friend has just told you.
4. Keep an open mind. Control freaks stop at the first adequate solution. Keep thinking even if it's uncomfortable.
5. Set goals and try to stick to them.