Anyone know of a study or methodical analysis anywhere (on the web or in a publication) assessing the character and extent of the influence of this "money in po

Anyone know of a study or methodical analysis anywhere (on the web or in a publication) assessing the character and extent of the influence of this "money in politics"? I would love to see it. It seems to me that massive campaign donations from corporations are only effective when a large fraction of the voters is voting in an ill-informed, rather mindless fashion. And as long as voters behave thus, it's not clear (to me) that it would take much money at all to undermine the effectiveness of a democracy.