Guardian Unlimited | Life | It's not just the hormones ...

"The remodelling of the cortex helps explain another feature of teenagers: their astonishing level of self-centredeness. For a while, as their brain is undergoing changes, they find it hard to recognise other's emotions. If you show teenagers pictures of faces, they will be some 20% less accurate in gauging the emotions depicted, not recovering this ability until they are 18 or so. This may be one of the reasons why they seem unable to read the signs, when treading on thin ice with their behaviour, with no appreciation of the impact of what they are doing on those around them. Teenagers exist in a universe of one."