At the next table in the cafe where I was working this morning, a young woman spent a whole hour talking excitedly to her older companion about herself, her hopes and aspirations for her job, her romantic relationship and her home. It was hard to avoid the impression that she thought herself the centre of the Universe, her dreams eminently fascinating and important.

Is this simply what young people or “millennials” (people born after 1980) are like these days? Fuelled by the endless opportunity for self-promotion and self-reflection on social media, combined with a wider culture that’s arguably placed greater emphasis on the importance of self-esteem than learning, have young people’s personalities changed from earlier generations to become more narcissistic and selfish?

Psychologists are divided. Some say the evidence that the young have become “Generation Me” is overwhelming, yet others counter just as strongly that this simply isn’t true. Meanwhile, more encouraging evidence is emerging to show positive trends in how our personalities seem to be changing over time, similar to the way that intelligence has increased over the generations.