A recent article in the Sydney Morning Herald made a case for knowing about one’s own personality predispositions, which can be useful, but only with significant caveats. 

 

The first issue is what you think ‘personality’ means. There is a tendency to think of it as a fixed part of our nature, but in fact most of personality is habitual, conditioned behaviour. Which is just as well – if it were hard-wired and unalterable there wouldn’t be much point in training! The second issue is how it is assessed. Conventionally this is based on psychometric questionnaires, but their usefulness depends entirely on whether they are valid and reliable: do they measure what they claims to measure, and do they do so consistently? 

 

The evidence for the reliability of many widely-used scales is sorely lacking, but some in particular have been marketed as if they were an infallible crystal ball. No psychometric questionnaire can ever assess personality with 100% accuracy, owing to error variance. For example, when completing it you try to work out what’s being measured, so that you can cast yourself in the best possible light. Or one of the questions may be related to something upsetting that happened to you the previous day. In the first case your answer will be biased by ‘faking good’, and in the second it may not reflect how you typically behave. 

 

Equally important is the question of validity. Sometimes the only evidence is that the questionnaire correlates with an existing scale claiming to measure the same thing, but the scale used as the criterion may itself be fatally biased. A much more powerful alternative source of validation evidence comes from the biological system. For example, in The Challenge of Change Resilience Training programme we define stress as ruminating about emotional upset. Any demanding situation we respond to provokes the ‘fight or flight’ response, facilitated by increases in adrenal hormones such as adrenaline and cortisol. This is entirely appropriate, but only in the short term – continued high levels of adrenaline and cortisol lead to sustained high blood pressure and immune compromise. Since intrusive negative thoughts continue to provoke adrenal activation long after the event, we predicted that chronic ruminators would not only be less happy but would also show delayed cardiovascular recovery, prolonged cortisol secretion and less efficient immune systems. Our experiments confirmed these predictions, and provided unambiguous physiological evidence for our rumination questionnaire. 

 

The newspaper article focused on extraversion-introversion, and gave good reasons why knowing about it might be useful. There is ample evidence that extraverts have lower levels of resting brain arousal than introverts, and consequently are ‘stimulus-hungry’ – they seek stimulation in order to maintain optimal arousal, while introverts avoid stimulation for the same reason. Extraverts consequently have very low boredom thresholds, while introverts find they can sustain attention for much longer. This difference plainly has a huge impact on working style: if you have tasks that require sustained attention to detail don’t ask an extravert to do them! Likewise, if there are issues for which quick decisions are required, introverts might not be the best people to deal with them. However, the article emphasised only one aspect of extraversion, which is the familiar tendency to be outgoing and sociable. The other, more important facet of extraversion is impulsivity, and impulsiveness carries a hazard: impulsive extraverts are inclined to make extremely risky decisions. 

 

So it is important not just to know about whether you’re extraverted, but also whether that tendency can be attributed mainly to sociability or impulsiveness. The two components are of course correlated, but they can be distinguished from one another. It is equally important to remember that in any random sample of people, some will be extraverted and some introverted, but most will be in the middle, neither particularly extraverted nor introverted (so-called ‘ambiverts’). The distribution of arousal levels, and hence extraversion-introversion, takes the form of a bell-curve, with most people in the middle. As you move towards the extremes of extraversion and introversion there are fewer and fewer people, and having the optimum level of arousal is in fact the norm.

 

Because extraversion-introversion is strongly influenced by biogenetic predispositions it is resistant to change, but it doesn’t carry any particular value-bias and is not implicated in stress. Being extraverted or introverted is not the same as being high or low on rumination, where there are significant health costs to having a high score. Extraversion-introversion can be used in selection procedures to match people to jobs, although this again needs to be done with great caution – psychometric scale scores should at best be only a part of the selection process, and should only be used if they’ve been specifically validated in the context you’re selecting for. Since much of our personality make-up is habitual, if there are vulnerabilities they can be changed with training, rather than forming the basis for selection decisions.

 

In The Challenge of Change system we use a wide range of psychometric scales that we have purpose-designed and validated to meet the particular needs of the Resilience Training and Dream Team programmes. The Challenge of Change Profile used in the Resilience Training programme highlights factors that the research has shown to be implicated in the stress response, but which can be changed by implementing the training. We’ve also developed a measure of extraversion-introversion that distinguishes clearly between the components of sociability and impulsiveness. The questionnaire forms an integral part of the Dream Team programme, and using valid and reliable psychometric scales in this way has added significantly to the power and effectiveness of The Challenge of Change training suite.

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