In a survey of 416 Scottish octogenarians, reserachers found that being smart doesn't make you happier.

�Neither childhood IQ, IQ at 80 or any change in IQ over a lifetime appear to have any bearing on how satisfied you are with how your life has turned out,� Gow adds. �Maybe all that is necessary is that you have the ability to carry out your daily tasks."

The researchers plan to continue studying the group of pensioners to examine what effect changes in cognitive function - over shorter timescales - may have on happiness in increasing old age.

HedgeFundGuy thinks this is because "the benefit of solving problems is balanced by the greater awareness of one's various suboptimalities." But is it really about how happy I am when I'm old? By the time I'm 80, I suppose carrying out daily tasks is quite primary -- given my experience with seniors' obsession with 'regularity', that seems plausible. But my ability to do things now matters greatly too. Put differently: How much 'happiness' will I sacrifice now to assure greater happiness at age 80? It seems to me there should be discounting.