Consider first the consistent discovery that beneath their hubris and egomania, many narcissists actually suffer from chronic low self-esteem. This has been demonstrated in many different ways, including using a version of the “implicit association test”, which in this context measures how readily people associate words referring to the self with pleasant or unpleasant words. One telling study found that highly narcissistic people said they had high self-esteem, yet when tested in the lab, they were very quick to associate self-related words like “me”, “mine” or “myself” with unpleasant words like “pain”, “agony” and “death”.

Another imaginative method that’s uncovered the inner fragility of the narcissist is the so-called bogus pipeline technique. Some of the participants are wired up to physiological recording equipment that they’re told will reveal whether they are lying, while others in a comparison control condition are connected to the equipment but they’re told it has been turned off. A study involving 71 women found that the narcissists among the participants reported having much lower self-esteem when they felt their lies would be unmasked, compared with those narcissists in the control condition. Indeed, they even reported lower self-worth than women who weren’t narcissists.

Increasingly, this picture of the narcissist as over-compensating for their private self-doubt is being supported by findings from brain imaging research. For example, one study involved male teenagers having their brains scanned while they played a collaborative computer game called cyber-ball. When their team-mates ignored them, the more narcissistic participants didn’t say it bothered them any more than the others, and yet their brains showed unusually high activity levels in regions that have previously been associated with the experience of social and emotional pain.