This show from the BBC examines personality traits or typology and they suggest that there's two sorts of people optimists and pessimists and they featured a programme on a computer which it was suggested could rewire the brain's unconscious negativity and therefore make you more optimistic than pessismistic and also that that is the only real and important division between people (for those that are interested the science was called CBM, cognitive bias something).

It was suggested that this could combat anxiety but not depression.

It was suggested that an optimism bias, including an optimism bias about aging, could result in seven plus years of life expectancy, to give some perspective to this the show suggested that if cancer could be cured it could add three years only to most peoples life expectancy (I was a little surprised at that and would have to crunch the numbers because I know a lot of younger people, in their thirties who have contracted different sorts of cancers and that would mean they have shorter life expectancy than I would think is the average in the UK).

I am interested because I know that I definitely belive in cognitive biases, also in the power of cultural memes or societal biases, although I'm not sure if older or other categorisations of personality such as introversion, extroversion etc. dont remain valid.