Quotes from Daniel Nettle

However, robust evidence shows that people systematically overestimate the probability of positive future contingencies, and underestimate the probability of negative ones — only those who are depressed or dysphoric come to accurate assessments.

Lessened theory of mind processing has also been linked to paranoia. After all, if one does not accurately model the mental state of another, one may treat it as hostile.

The fear programme is designed to get us away from things that are likely to harm us. If we had to make an analogous claim about the purpose of the happiness system, we would be most likely to say that it is there to keep us moving towards things that are likely to be good for us in some appropriate biological sense--mating, good food, pleasant environment--and away from things that are bad for us.

non-twin children who are adopted into different families resemble their biological siblings in personality, even though they may rarely or never have met them, and they have no greater resemblance in personality to their adoptive siblings, who they grew up with, than they do to randomly chosen strangers. The correlation is essentially zero.