The truth lies somewhere in between. More thought, study, and analysis goes into the all important decision of how to vote than is generally recognized. Members are called upon hundreds of times a year to cast a yea or nay on a wide variety of bills, motions, and amendments. They receive mailbags full of letters, e-mails, faxes, and phone calls from constituents, all expressing a wide array of conflicting points of view.
Members also hear statements from expert witnesses testifying before congressional hearings.
Special interest groups send them background material. Congressional agencies provide reports and studies. Colleagues in Congress send letters with recommendations. There is no shortage of information on both sides of any issue before the Congress. The process of making the decision of how to vote is a highly individual one and cannot be easily categorized.