A quote from Elizabeth Kolbert in The New Yorker, 25 February 2008

Like neoclassical economics, much democratic theory rests on the assumption that people are rational. Here, too, empirical evidence suggests otherwise. Voters, it has been demonstrated, are influenced by factors ranging from how names are placed on a ballot to the jut of a politician’s jaw. A 2004 study of New York City primary-election results put the advantage of being listed first on the ballot for a local office at more than three per cent – enough of a boost to turn many races. (For statewide office, the advantage was around two per cent.) A 2005 study, conducted by psychologists at Princeton, showed that it was possible to predict the results of congressional contests by using photographs. Researchers presented subjects with fleeting images of candidates’ faces. Those candidates who, in the subjects’ opinion, looked more “competent” won about seventy per cent of the time.