The New York Times Magazine published another interesting article:
definitely worth reading -- the article tries to answer questions about our expectations of happiness. will that BMW make us happy? researchers have found that it will probably not make us as happy as we expect. will a death of a loved one cause us incredible grief? maybe, but the long term effect of a death will make us less sad than we suspect.
according to the article, humans tend not to predict very well the gradation of happiness.