A psychology professor has recently written a book about the value of regrets: mild regret is useful for driving new action, he reckons (although severe regret "can be the first step to mental illness" - so watch your step there!).

And while we're on the subject of the role of emotion, a new study has found that we know more negative emotion words than positive or neutral words (this is not some vagary of the English language - both English and Spanish speakers were tested). The theory is that we don't spend a lot of time analyzing positive emotions - if we feel good, then great, who cares about nuance - whereas for negative emotions, we delve into the detail - why do we feel bad, in what way do we feel bad, etc. Maybe we'd be happier if we didn't???